Photochemie - Neueste Forschungsartikel der Fachverlage
Aktuelle Fachartikel zur Photochemie und Photobiologie, sortiert nach Erscheinungsdatum.
Die Urheberrechte und
Veroeffentlichungsrechte der in der nachfolgenden Liste aufgefuehrten
Fachartikel liegen bei den jeweiligen Verlagen, die am Ende des
als Quelle genannt werden. Diese sind auch fuer die Inhalte
Hinweise zur Veroeffentlichung Ihrer
Pressmitteilung unter Internetchemie.Info entnehmen Sie bitte der
Diese Seite koennen Sie mit folgender Tastenkombination nach Stichwoertern
durchsuchen: <STRG> und <F>.
Auf dieser Seite
beruecksichtige naturwissenschaftliche Journale:
Photochemical & Photobiological Sciences - published by
The Royal Society of Chemistry -
PPS meets the growing information needs of scientists working in the areas of photochemistry and photobiology, and indeed, encourages a synergism between these two important research areas. This international journal is published monthly on behalf of the European Photochemistry Association (EPA), the European Society for Photobiology (ESP), the Asia and Oceania Society for Photobiology (AOSP) and the Korean Society of Photoscience (KSP), and is available in both print and electronic formats.
Photochemistry and Photobiology - published by
... publishes original research articles and reviews on current topics in photoscience.
Aktuelle wissenschaftliche Fachartikel der
The UV absorption, phosphorescence and phosphorescence-excitation spectra of benzophenone (BP) derivatives used as organic UV absorbers have been observed in rigid solutions at 77 K. The triplet–triplet absorption spectra have been observed in acetonitrile at room temperature. The BP derivatives studied are 2,2′,4,4′-tetrahydroxybenzophenone (BP-2), 2-hydroxy-4-methoxybenzophenone (BP-3), 2,2′-dihydroxy-4,4′-dimethoxybenzophenone (BP-6), 5-chloro-2-hydroxybenzophenone (BP-7) and 2-hydroxy-4-n-octyloxybenzophenone (BP-12). The energy levels and lifetimes of the lowest excited triplet (T1) states of these BP derivatives were determined from the first peak of phosphorescence. The time-resolved near-IR emission spectrum of singlet oxygen generated by photosensitization with BP-7 was observed in acetonitrile at room temperature. BP-2, BP-3, BP-6 and BP-12 show photoinduced phosphorescence enhancement in ethanol at 77 K. The possible mechanism of the observed phosphorescence enhancement is discussed. The T1 states of 2-hydroxy-5-methylbenzophenone, 4-methoxybenzophenone and 2,4′-dimethoxybenzophenone have been studied for comparison.
The energy levels and lifetimes of the lowest excited triplet states of benzophenone (BP) derivatives, BP-2, BP-3, BP-6, BP-7 and BP-12, used as organic UV absorbers in cosmetic sunscreens were determined in rigid solutions at 77 K. The time-resolved near-IR emission spectrum of singlet oxygen generated by photosensitization with BP-7 was observed in acetonitrile at room temperature. BP-2, BP-3, BP-6 and BP-12 show photoinduced phosphorescence enhancement in ethanol at 77 K.
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50428J, Paper
Cenchao Shen, Terence Turney, Terrence Piva, Bryce Feltis, Paul Wright This is an Accepted Manuscript, which has been through the RSC Publishing peer review process and has been accepted for publication. Accepted manuscripts are published online shortly after acceptance. This version of the article will be replaced by the fully edited, formatted and proof read Advance Article as soon as this is available. The content of this RSS Feed (c) The Royal Society of Chemistry
Francesco Zaratti, Ruben D Piacentini, Hector A Guillen, Sergio Cabrera, Ben Liley, Richard McKenzie The standardisation of UV information to the public through the UV Index (UVI) has been hugely beneficial since its endorsement by multiple international agencies more than 10 years ago. It... The content of this RSS Feed (c) The Royal Society of Chemistry
We previously demonstrated that the non-ionic surfactants, nonylphenol polyethoxylates (NPEOs) induced the phosphorylation of histone H2AX (γ-H2AX), accompanied by DNA double strand breaks (DSBs), and that exposure to ultraviolet (UV) degraded NPEOs, which sometimes enhanced their DNA-damaging ability. In this study, we showed that linear alkylbenzene sulfonates (LAS), general anion surfactants, also generated DSBs with γ-H2AX, and this ability was attenuated by UVB exposure. In the human breast adenocarcinoma cell line, MCF-7, γ-H2AX was generated in a dose-dependent manner immediately after cells were treated with LAS, and this was attributed to the formation of DSBs and was independent of cell cycle phases. The ability to generate γ-H2AX was markedly reduced in LAS exposed to UVB. HPLC analysis revealed that LAS were a mixture of various alkyl chain lengths, the peaks of which were detected at individual retention times. UVB evenly decreased all peaks of LAS, without migration of peaks to other retention times, which indicated that UVB may degrade the benzene ring of LAS, but did not shorten the alkyl chains. UVB is an important environmental factor in the degradation of LAS exhibiting the ability to induce DSBs, the most serious type of DNA damage.
This article is protected by copyright. All rights reserved.
In past decades, researches on radiation-induced bystander effect mainly focused on ionizing radiation such as α-particle, β-particle, X-ray and γ-ray. But few researches have been conducted on the ability of ultraviolet (UV) radiation-induced bystander effect, and knowledge of UVC-induced bystander effect is far limited. Here, we adopted medium transfer experiment to detect whether UVC could cause bystander effect in Chinese hamster V79 cells. We determined the cell viability, apoptosis rate, chromosome aberration and ultrastructure changes, respectively. Our results showed that: (1) the viability of UVC-irradiated V79 cells declined significantly with the dosage of UVC; (2) similar to the irradiated cells, the main death type of bystander cells cultured in irradiation conditioned medium (ICMs) was also apoptosis; (3) soluble factors secreted by UVC-irradiated cells could induce bystander effect in V79 cells; (4) cells treated with 4 h ICM collected from 90 mJ cm−2 UVC-irradiated cells displayed the strongest response. Our data revealed that UVC could cause bystander effect through the medium soluble factors excreted from irradiated cells and this bystander effect was a novel quantitative and kinetic response. These findings might provide a foundation to further explore the exact soluble bystander factors and detailed mechanism underlying UVC-induced bystander effect.
This study showed that UVC radiation induced some damage in irradiated V79 cells, which might initiate apoptosis progress when damage couldn't be repaired. The UVC-irradiated apoptotic cells released gradually some soluble factors into irradiated conditioned medium (ICMs) which finally induced bystander effect in unirradiated V79 cells.
Mycosis fungoides (MF) and parapsoriasis (PP) are major dermatologic conditions for which phototherapy continues to be a successful and valuable treatment option. UVA-1 phototherapy is effective in the management of cutaneous T-cell mediated diseases. The aim of the study was to evaluate the efficacy and safety of low-dose UVA-1 phototherapy for the management of PP/early-stage MF. A total of 30 patients, diagnosed with MF (n:19) or PP (n:11) were enrolled to the study. All patients were managed with low-dose UVA-1 (20 or 30 J cm−2). Response was assessed clinically and immunohistochemically. UVA-1 treatment led to clinical and histological complete remission (CR) in 11 of 19 MF patients (57.9%), partial remission (PR) in three of 19 (15.8%), after a mean cumulative dose of 1665 (range, 860–3120) J cm−2 and mean number of 73 exposure (range, 43–107) sessions. Five patients with PP (45.5%) showed CR, and PR was observed in six patients with PP (54.5%) after a mean cumulative dose of 1723 (range, 1060–3030) J cm−2 and mean number of 74 exposure (range, 53–101) sessions. We conclude that low-dose UVA-1 therapy seems to be an effective, safe, and well-tolerated treatment option for patients with PP/early-stage MF.
Skin-directed therapies are currently available treatment options for plaque type PP/early-stage MF with some limitations, and management of the diseases is still challenging. Ultraviolet A-1 (340–400 nm) phototherapy was first described in 1978 and it has became a valuable treatment for sclerotic and T-cell mediated diseases, more deeply penetrates than UVB. This study showed that Low-dose UVA-1 therapy seems to be a safe and effective alternative to other therapeutic options in patients with PP/early-stage MF who do not tolerate or respond to PUVA and UVB therapy, without systemic effect.
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50419K, Paper
Isabel Viseu , Raquel Fonseca Correia, Suzana M. Andrade The photosynthetic pigments of higher plants exist in complex oligomeric states, which are difficult to study in vivo. To investigate aggregation processes of chlorophyll a (Chl a), we used an... The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50317H, Paper
Patricia Elizabeth Garcia, Marcela Andrea Ferraro, A. Patricia Perez, Horacio Zagarese, Maria Dieguez The bio-accumulation of mycosporine-like amino acids (MAAs) is common in planktonic copepods that inhabit environments exposed to high levels of solar radiation. MAAs accumulation in copepods can be affected both... The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50413A, Paper
Alena Knak, Johannes Regensburger, Tim Maisch, Wolfgang Baeumler Deleterious effects of UV radiation in tissue are usually attributed to different mechanisms. Absorption of UVB radiation in cell constituents like DNA causes photochemical reactions. Absorption of UVA radiation in... The content of this RSS Feed (c) The Royal Society of Chemistry
Human outdoor activities are randomly orientated at different angles to the sun. To quantify the ocular UV and biologically effective UV (UVBE) (i.e., the ocular UV irradiance exposure for photokeratitis (UVpker), photoconjunctivitis (UVpcon) and cataract (UVcat)) exposure for different rotation angle ranges, a rotating manikin was used to monitor the ocular UV exposure at different rotation angles in clear skies during July 2010 in Sanya, China. As a result, the ocular UV and UVBE irradiance was directly influenced by the rotation angle variations, primarily for the 120° rotation angle ranges facing the morning and afternoon sun when the solar elevation was lower than 60°; during these times, the UV and UVBE spectral irradiance decreased as the rotation angle increased. When compared to the 360° rotation angle ranges (which were considered to be the average exposure situation), the cumulative ocular UVBE for 60°, 120° and 180° rotation angle ranges were maximumly 91% (UVcat), 94% (UVpker) and 121% (UVpcon); 71% (UVcat), 74% (UVpker) and 95% (UVpcon); 42%(UVcat), 45%(UVpker) and 55% (UVpcon) higher respectively. Meanwhile, the cumulative ocular UVBE for the 180° rotation angle ranges facing away from the sun were 46% (UVpker), 59% (UVpcon) and 45% (UVcat) lower.
This article is protected by copyright. All rights reserved.
Singlet oxygen, created in photosensitization, peroxidizes unsaturated fatty-acids of the membrane's lipids. This generates alcoholic or aldehyde groups at double bonds’ breakage points. In a previous study we examined the leakage of a K+-induced cross-membrane electric potential of liposomes that undergo photosensitization. The question remains to what extent peroxidized lipids can compromise the stability of the membrane. In this work, we studied the effect of the oxidatively modified lipids PGPC and ALDOPC in the membrane on its stability, by monitoring the membrane electric potential with the potentiometric dye DiSC2(5). As the content of the modified lipids increases the membrane becomes less stable, and even at just 2% of the modified lipids the membrane's integrity is affected, in respect to the leakage of ions through it. When the liposomes that contain the modified lipids undergo photosensitization by hematoporphyrin, the lipid bilayer becomes even more unstable and passage of ions is accelerated. We conclude that the existence of lipids with a shortened fatty acid that is terminated by a carboxylic acid or an aldehyde and more so when photosensitized damage occurs to unsaturated fatty acids in lecithin, add up to a critical alteration of the membrane, which becomes leaky to ions.
This article is protected by copyright. All rights reserved.
Time binning is used to increase the number of photon counts in the peak channel of stimulated emission depletion fluorescence lifetime decay curves to determine how it affects the resulting lifetime image. The fluorescence lifetime of the fluorophore, Alexa Fluor 594 phalloidin, bound to F-actin is probed in cultured S2 cells at a spatial resolution of ~40 nm. This corresponds to a 10-fold smaller probe volume compared to confocal imaging, and a reduced number of photons contributing to the signal. Pixel-by-pixel fluorescence lifetime measurements and error analysis show that an average of 40 ± 30 photon counts in the peak channel with a signal-to-noise ratio of 20 is enough to calculate a reliable fluorescence lifetime from a single exponential fluorescence decay. No heterogeneity in the actin cytoskeleton in different regions of the cultured cells was measured in the 40–400 nm spatial regime.
Photon counts in the peak channel of stimulated emission depletion fluorescence lifetime decay curves are increased by time binning without affecting the spatial resolution of the measurements. The fluorescence lifetime of Alexa Fluor 594 phalloidin bound to F-actin is probed in cultured cells at a spatial resolution 10-fold better compared to confocal imaging. Pixel-by-pixel fluorescence lifetime measurements and error analysis show that an average of 40 ± 30 counts in the peak channel with a signal-to-noise ratio of 20 is enough to calculate a reliable fluorescence lifetime from a single exponential fluorescence decay.
Personal ultraviolet dosimeters have been used in epidemiological studies to understand the risks and benefits of individuals’ exposure to solar ultraviolet radiation (UVR). We investigated the types and determinants of non-compliance associated with a protocol for use of polysulphone UVR dosimeters. In the AusD Study, 1,002 Australian adults (aged 18-75 years) were asked to wear a new dosimeter on their wrist each day for 10 consecutive days to quantify their daily exposure to solar UVR. Of the 10,020 dosimeters distributed, 296 (3%) were not returned or used (Type I non-compliance) and other usage errors were reported for 763 (8%) returned dosimeters (Type II non-compliance). Type I errors were more common in participants with predominantly outdoor occupations. Type II errors were reported more frequently on the first day of measurement; weekend days or rainy days; and among females; younger people; more educated participants or those with outdoor occupations. Half (50%) the participants reported a non-compliance error on at least one day during the 10-day period. However, 92% of participants had at least 7 days of usable data without any apparent non-compliance issues. The factors identified should be considered when designing future UVR dosimetry studies.
This article is protected by copyright. All rights reserved.
Structure-activity relationships have been widely reported for porphyrin and phthalocyanine photosensitizers, but not for phenothiazinium derivatives. Here four phenothiazinium salts (methylene blue, toluidine blue O, 1,9-dimethyl methylene blue and the pentacyclic derivative DO15) were used to investigate how the ability to damage membranes is affected by membrane/solution partition, photophysical properties and tendency to aggregation of the photosensitizer. These two latter aspects were studied both in isotropic solutions and in membranes. Membrane damage was assessed by leakage of a fluorescent probe entrapped in liposomes and by generation of thiobarbituric acid-reactive species (TBARS), while structural changes at the lipid bilayer were detected by small angle X-ray scattering. We observed that all compounds had similar singlet oxygen quantum yields in ethanol, but only the photosensitizers that had higher membrane/solution partition (1,9-dimethyl methylene blue and DO15, the latter having the higher value) could permeabilize the lipid bilayer. Moreover, of these two photosensitizers, only DO15 altered membrane structure, a result that was attributed to its destabilization of higher order aggregates, generation of higher amounts of singlet oxygen within the membranes and effective electron transfer reaction within its dimers. We concluded that membrane-based protocols can provide a better insight on the PDT efficiency of the photosensitizer.
This article is protected by copyright. All rights reserved.
We report a low-temperature fluorescence spectroscopy study of the PAS-GAF-PHY sensory module of Cph1 phytochrome, its Y263F mutant (both with known 3D structures) as well as Y263H and Y263S to connect their photochemical parameters with intramolecular interactions. None of the holoproteins showed photochemical activity at low temperature and the activation barriers for the Pr→lumi-R photoreaction (2.5-3.1 kJ mol−1) and fluorescence quantum yields (0.29-0.42) were similar. The effect of the mutations on Pr→Pfr photoconversion efficiency (ΦPr→Pfr) was observed primarily at the prelumi-R S0 bifurcation point corresponding to the conical intersection of the energy surfaces at which the molecule relaxes to form lumi-R or Pr, lowering ΦPr→Pfr from 0.13 in the wild type to 0.05 - 0.07 in the mutants. We suggest that the Ea activation barrier in the Pr* S1 excited state might correspond to the D-ring (C19) carbonyl – H290 hydrogen bond or possibly to the hindrance caused by the C131/C171 methyl groups of the C- and D-rings. The critical role of the tyrosine hydroxyl group can be at the prelumi-R bifurcation point to optimize the yield of the photoprocess and energy storage in the form of lumi-R for subsequent rearrangement processes culminating in Pfr formation.
This article is protected by copyright. All rights reserved.
Resveratrol polymer has better effects than monomer in some aspects as reported, but most of synthetic methods acquire severe conditions and no analgesic effects are investigated. A novel method is found to synthesize resveratrol polymer by excitation of photosensitizer pheophorbide at red light of 630nm. The polymer was analyzed by fluorescence spectra and HPLC, further isolated by preparative liquid chromatography and identified as a resveratrol dimer by MS and NMR. Analgesic effects were measured by acetic acid writhing and hot plate test in mice. The resveratrol dimer has the stronger analgesic effects than monomer, and drug combination of the dimer and cobra neurotoxin enhances and prolongs analgesic effects, suggesting the synergistic action. Simulation of molecular interaction reveals that the dimer spontaneously binds to cobra neurotoxin and makes a complex substance. The dimer can interact with cyclooxygenase-2, μ receptor and nicotine receptor, the synergistic analgesic effects of the complex are attributed to its multiple targets role. The combination of resveratrol dimer and cobra neurotoxin may make up for their deficiencies in analgesic effects, and has prospects in clinical use.
This article is protected by copyright. All rights reserved.
Excessive exposure to ultraviolet radiation (UVR) is considered the most important environmental risk factor in the development of melanoma and skin cancer. Outdoor workers are among those with the highest risk from exposure to solar UVR, as their daily activities constantly expose them to this radiation source. A study was carried out in Valencia, Spain, in summer 2012 and involved a group of 11 workers for a period of six 2-day recordings. Sensitive spore-film filter-type personal dosimeters (VioSpor) were used to measure erythemal UVR received by environmental agents in the course of their daily work. Median 2-day UV exposure was 6.2 standard erythema dose (SED), with 1 SED defined as effective 100 J m−2 when weighted with the Commission Internationale de L′Eclairage's (CIE) erythemal response function. These workers were found to receive a median of 8.3% total daily ambient ultraviolet erythemal radiation. Comparison with the occupational UV exposure limit showed that the subjects had received an erythemal UV dose in excess of occupational guidelines, indicating that protective measures against this risk are highly advisable.
The aim of this paper is to measure UV exposure of environmental agents in their occupational schedules in summer in Valencia province (Spain) using VioSpor personal dosimeters attached to several parts of their bodies. Due to its geographical situation, Valencia receives large UVR doses throughout the year, and the work of environmental agents is directly related to the protection, care, and custody of natural, often in mountainous areas. Comparison with the occupational UV exposure limit showed that the agents received an erythemal UV dose in excess of occupational guidelines, indicating that protective measures against this risk are highly advisable.
Very diverse carotenoid structures exist in the photosynthesis apparatus of different algae. Among them, the keto derivatives are regarded the most antioxidative. Therefore, four different keto carotenoids, peridinin, fucoxanthin, siphonaxanthin and astaxanthin fatty acid monoesters, were isolated and purified from Amphidinium carterae, Phaeodactylum tricornutum, Caulerpa taxifolia and Haematococcus pluvialis, respectively. The carotenoids were assayed as inhibitors of photosensitizer initiated reactions or scavengers of radicals in the early events generating reactive oxygen species as starters for peroxidation and as protectants against the whole reaction chain finally leading to lipid peroxidation. These in vitro studies demonstrated the substantial antioxidative properties as indicated by the IC50 values of all four keto carotenoids with superior protection by astaxanthin fatty acid monoesters which were as effective as free astaxanthin and of peridinin against radicals. As an example, the in vivo relevance of fucoxanthin for protection of photosynthesis from excess light and from peroxidative agents was evaluated with intact cells. Cultures of P. tricornutum with decreased fucoxanthin content generated by inhibitor treatment were exposed to strong light or cumene hydroperoxyde. In each case, oxidation of chlorophyll as marker for damaging of the photosynthesis apparatus was less severe when the fucoxanthin was at maximum level.
Carotenoids and especially their keto derivatives are known for their antioxidative potential. Therefore the keto carotenoids peridinin, siphonaxanthin, fucoxanthin and astaxanthin mono fatty acid ester were isolated from different algae. They were assayed for their antioxidative properties as quenchers of singlet oxygen and oxo radicals and their potential was determined to protect against singlet oxygen- or radical-mediated peroxidation reactions.
The aim of this study was to investigate the necrosis-avid agent hypericin as a potential indicator for determination of myocardial infarction (MI). Male Sprague-Dawley rats (n = 30) weighing 350 ± 20 g were subjected to acute reperfused MI. Animals were divided into four groups (n = 6), in which hypericin was intravenously injected at 0, 1, 2 and 5 mg kg−1 respectively. One day after injection, rats were euthanized with their hearts excised for qualitative and quantitative studies by means of microscopic fluorescence examination to decide the dosage of hypericin. Another group was injected with hypericin at the decided dose and evaluated by fluorescence macroscopy in colocalization with triphenyltetrazoliumchloride (TTC) and histomorphology. Infarct-to-normal contrast ratio and relative infarct size were quantified. Hypericin-induced red fluorescence was significantly brighter in necrotic than in viable myocardium as proven by a six times higher mean fluorescence density. Mean MI area was 35.66 ± 22.88% by hypericin fluorescence and 32.73 ± 21.98% by TTC staining (R2 = 0.9803). Global MI-volume was 34.56 ± 21.07% by hypericin and 35.11 ± 20.47% by TTC staining (R2 = 0.9933). The results confirm that hypericin specifically labeled necrosis, and enhanced the imaging contrast between the infarcted and normal myocardium, suggesting its potential applications for the assessment of myocardial viability.
The aim of this study was to investigate the necrosis avid agent hypericin as a potential indicator for determination of myocardial infarction. Animals were challenged with different doses of hypericin (0, 1, 2, and 5 mg kg−1) after an experimental myocardial infarction. Infarct-to-normal contrast ratio and relative infarct size were evaluated by fluorescence macroscopy in colocalization with triphenyltetrazoliumchloride and histomorphology. Results confirm that hypericin specifically labeled necrosis, and enhanced the imaging contrast between the infarcted and normal myocardium, suggesting its potential applications for the assessment of myocardial viability.
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50379H, Paper
Stefan Berdzinski, Nadine Strehmel, Heike Lindauer, Veronika Strehmel, Bernd Strehmel Chlorine substituted hexaarylbisimidazole (o-Cl-HABI) efficiently initiates radical polymerization of multifunctional acrylic esters in the presence of a heterocyclic mercapto compound if the latter can form its tautomeric thione. Exposure of... The content of this RSS Feed (c) The Royal Society of Chemistry
Cataract is the major cause for legal blindness in the world. Oxidative stress on the lens epithelial cells (hLECs) is the most important factor in cataract formation. Cumulative light-exposure from widely used light-emitting diodes (LEDs) may pose a potential oxidative threat to the lens epithelium, due to the high-energy blue light component in the white-light emission from diodes. In the interest of perfecting biosafety standards for LED domestic lighting, this study analyzed the photobiological effect of white LED light with different correlated color temperatures (CCTs) on cultured hLECs. The hLECs were cultured and cumulatively exposed to multichromatic white LED light with CCTs of 2954, 5624, and 7378 K. Cell viability of hLECs was measured by Cell Counting Kit-8 (CCK-8) assay. DNA damage was determined by alkaline comet assay. Intracellular reactive oxygen species (ROS) generation, cell cycle, and apoptosis were quantified by flow cytometry. Compared with 2954 and 5624 K LED light, LED light having a CCT of 7378 K caused overproduction of intracellular ROS and severe DNA damage, which triggered G2/M arrest and apoptosis. These results indicate that white LEDs with a high CCT could cause significant photobiological damage to hLECs.
Oxidative stress on the lens epithelial cells (hLECs) is the most important factor in cataract formation. Cumulative light exposure from widely used light-emitting diodes (LEDs) may pose a potential oxidative threat to the lens epithelium, due to the high-energy blue light component in the white-light emission from diodes. LED light having a CCT of 7378 K caused overproduction of intracellular ROS and severe cellular damage, which indicate that white LEDs with a high CCT could cause significant photobiological damage to hLECs and detailed industrial standards for this new artificial light source should be determined for the sake of ocular safety.
A series of heterogeneous catalysts was prepared by doping zinc oxide with different palladium loadings in the range of 0.5%–1.5%. The prepared catalysts were characterized by SEM, TEM and XRD. These catalysts were applied to study the degradation of Methyl tert-Butyl Ether (MTBE). An amount of 100 mg of each of these catalysts was added to an aqueous solution of 100 ppm of MTBE. The resulting mixtures were irradiated with UV light for a period of 5 h. A 99.7% removal of MTBE was achieved in the case of the zinc oxide photocatalyst particles doped with 1% Pd. The photoreaction was found to be a first-order one.
Approximately complete removal of MTBE was achieved within 5 h by using ZnO particles doped with 1% Pd. The efficient degradation of MTBE is due to the higher concentration of the hydroxyl radicals and to the presence of Pd that controls the recombination of photogenerated electron hole pair.
Fluorescein-dispersing titania gel films were prepared by the acid-catalyzed sol–gel reaction using a titanium alkoxide solution containing fluorescein. The molecular forms of fluorescein in the films, depending on its acid–base equilibria, and the complex formation and photoinduced electron transfer process between the dye and titania surface were investigated by fluorescence and photoelectric measurements. The titanium species were coordinated to the carboxylate and phenolate-like groups of the fluorescein species. The quantum efficiencies of the fluorescence quenching and photoelectric conversion were higher upon excitation of the dianion species interacting with the titania, i.e. the dye–titania complex. This result indicated that the dianion form was the most favorable for formation of the dye–titania complex exhibiting the highest electron transfer efficiency. Using nitric acid as the catalyst, the titania surface bonded to the fluorescein instead of the adsorbed nitrate ion during the steam treatment. The dye–titania complex formation played an important role in the electron injection from the dye to the titania conduction band.
Fluorescein-dispersing titania gel films were prepared by the acid-catalyzed sol–gel reaction using a titanium alkoxide solution containing fluorescein. The titanium species were coordinated to the carboxylate and phenolate-like groups of the fluorescein species. The quantum efficiencies of the fluorescence quenching and photoelectric conversion were higher upon excitation of the dianion species interacting with the titania, i.e. the dye–titania complex. Using nitric acid as the catalyst, the titania surface bonded to the fluorescein instead of the adsorbed nitrate ion during the steam treatment. The complex formation played an important role in the electron injection from the dye to the titania.
Xeroderma pigmentosum (XP) is a genetic disorder associated with defects in nucleotide excision repair, which eliminates a wide variety of helix-distorting types of DNA damage including sunlight-induced pyrimidine dimers. In addition to skin disease, approximately 30% of XP patients develop progressive neurological disease, which has been hypothesized to be associated with the accumulation of a particular type of oxidatively generated DNA damage called purine 8,5′-cyclo-2′-deoxynucleosides (purine cyclonucleosides). However, there are no currently available methods to detect purine cyclonucleosides in DNA without the need for DNA hydrolysis. In this study, we generated a novel monoclonal antibody (CdA-1) specific for purine cyclonucleosides in single-stranded DNA that recognizes 8,5′-cyclo-2′-deoxyadenosine (cyclo-dA). An immunoassay using CdA-1 revealed a linear dose response between known amounts of cyclo-dA in oligonucleotides and the antibody binding to them. The quantitative immunoassay revealed that treatment with Fenton-type reagents (CuCl2/H2O2/ascorbate) efficiently produces cyclo-dA in DNA in a dose-dependent manner. Moreover, immunofluorescent analysis using CdA-1 enabled the visualization of cyclo-dA in human osteosarcoma cells, which had been transfected with oligonucleotides containing cyclo-dA. Thus, the CdA-1 antibody is a valuable tool for the detection and quantification of cyclo-dA in DNA, and may be useful for characterizing the mechanism(s) underlying the development of XP neurological disease.
Xeroderma pigmentosum (XP) is a genetic disorder associated with defects in nucleotide excision repair, which eliminates a wide variety of helix-distorting DNA damage including sunlight-induced pyrimidine dimers. In addition to skin disease, approximately 30% of XP patients develop progressive neurological disease, which has been hypothesized to be associated with the accumulation of oxidatively generated DNA damage called purine cyclonucleosides. In this study, we generated a novel monoclonal antibody (CdA-1) specific for purine cyclonucleosides in DNA that recognizes 8,5′-cyclo-2′-deoxyadenosine (cyclo-dA). An immunofluorescent analysis using CdA-1 enabled the visualization of cyclo-dA (green dots) in human osteosarcoma cells, which had been transfected with oligonucleotides containing 5′S-cyclo-dA.
Biomaterials for in vivo fluorescence imaging are required to be biocompatible, nontoxic, photostable and highly fluorescent. Fluorescence must be in the near infrared (NIR) region of the electromagnetic spectrum to avoid absorption and autofluorescence of endogenous tissues. NIR fluorescent polystyrene nanoparticles may be considered ideal biomaterials for in vivo imaging applications. These NIR nanoparticles were prepared by a swelling process of polystyrene template nanoparticles with a hydrophobic NIR dye dissolved in a water-miscible swelling solvent, a method developed for preparation of nonbiodegradable nanoparticles, for NIR fluorescent bioimaging applications. This method overcomes common problems that occur with dye entrapment during nanoparticle formation such as loss of fluorescence and size polydispersity. Fluorescence intensity of the nanoparticles was found to be size dependent, and was optimized for differently sized nanoparticles. The resulting NIR nanoparticles were also found to be more fluorescent and highly photostable compared to the free dye in solution, showing their potential as biomaterials for in vivo fluorescence imaging.
In vivo fluorescence imaging requires the use of near IR fluorescent imaging agents, to avoid the absorbance and autofluorescence of endogenous tissues that occur at visible wavelengths. Near IR dye was encapsulated into polystyrene nanoparticles via a swelling process. The dye encapsulation process was performed for a series of differently sized nanoparticles, without affecting the relatively uniform size distribution of each size. The method used was found to be appropriate for nanoparticles averaging approximately 20–100 nm in size. The resulting nanoparticles were highly fluorescent and highly photostable, and with appropriate surface modification, have potential for biological and in vivo imaging applications.
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50302J, Paper
Dirk Ziegenbalg, Gunter Kreisel, Dieter Weiss, Dana Kralisch In this work, the use of OLEDs as light sources to initiate photochemical reactions is published for the first time. A newly developed modular photoreactor system utilising microstructured reactors was... The content of this RSS Feed (c) The Royal Society of Chemistry
This paper reported the photophysics of 7-(diethylamino)Coumarin-3-carboxylic acid N-succinimidyl ester (7-DCCAE) in different neat solvents of varying polarity using steady state absorption, fluorescence emission and picosecond time resolved spectroscopy. In non polar solvents, the dye molecule predominantly exists in non polar structure and exhibits very low value of non-radiative decay rate constant (knr), demonstrating the emission takes place from S1-LE to S0 ground state. The fluorescence quantum yields, lifetime values of 7-DCCAE in different solvents are rationalised on the basis of intramolecular charge transfer (ICT) followed by twisted intramolecular charge transfer state formation (TICT) as well as specific solute-solvent interactions. Several solvatochromic models (such as Lippert, Dimroth, Kamlet-Taft, Catalán 3P and Catalán 4P models) was used to analysis the solvatochromic shift of 7-DCCAE in different solvents. The different empirical models shows the observed results are better correlate for non-chlorinated solvents and provide statistically significant best fits result. A comparison was done between comparatively new solvatochromic model (Catalán 3P and Catalán 4P model) with Kamlet-Taft model. The ground state structure of the said molecule was optimized by using Density Functional Theory (DFT)
This article is protected by copyright. All rights reserved.
Here, we report the synthesis, photophysical properties and photodynamic effects in DLA live cells of three water soluble squaraine dyes, viz. bisbenzothiazolium squaraine dyes SQMI and SQDI with iodine in one and both benzothiazolium units, respectively, and an unsymmetrical squaraine dye ASQI containing iodinated benzothiazolium and aniline substituents. The diiodinated SQDI showed an anomalous trend in both fluorescence and triplet quantum yields over the monoiodinated SQMI, with SQDI showing higher fluorescence and lower triplet quantum yields compared to SQMI. Nanosecond laser flash photolysis of SQDI and SQMI indicated the formation of triplet excited states with quantum yield of 0.19 and 0.26, respectively. On photoirradiation, both the SQDI and SQMI generate singlet oxygen and it was observed that both dyes undergoing oxidation reactions with the singlet oxygen generated. ASQI which exhibited a lower triplet quantum yield of 0.06 was, however, stable and did not react with the singlet oxygen generated. In vitro cytotoxicity studies of these dyes in DLA live cells were performed using Trypan blue dye exclusion method and it reflect an order of cytotoxicity of SQDI>SQMI>ASQI. Intracellular generation of the ROS was confirmed by dichlorofluorescein assay after the in vitro PDT.
Synthesis, photophysical properties and photodynamic effects in DLA live cells of three water soluble squaraine dyes, SQDI, SQMI and ASQI, are presented. On photoirradiation, both the SQDI and SQMI generate singlet oxygen where both the dyes undergoing oxidation reactions with the singlet oxygen generated, whereas ASQI was stable and did not react with the singlet oxygen. In vitro cytotoxicity studies of these dyes in DLA cells were performed using Trypan blue dye exclusion method and intracellular generation of ROS was confirmed using dichlorofluorescein assay after the in vitro PDT.
The whole pathways for photoluminescence, which include absorption, relaxation and emission, of firefly luciferin in aqueous solutions of different pH values with different photoexcitation energies were theoretically investigated by considering protonation/deprotonation. It is experimentally known that the color of fluorescence changes from green to red with a decrease in the photoexcitation energy. We confirmed with the theoretical analysis that the peak energy shift in the fluorescence spectra with varying photoenergies is due to a change in photoluminescence pathway. When the photoexcitation energy is decreased, the red emission from a monoanion form of firefly luciferin with carboxylate and phenolate groups and N-protonated thiazoline ring occurs irrespective of the pH values. However, because the species abundant in the solution and those excited by the photon depend on the solution pH, the pathway leading to the monoanion form changes with the solution pH.
By considering protonation/deprotonation, the whole pathways for photoluminescence of firefly luciferin in aqueous solutions of different pH values with different photoexcitation energies were theoretically investigated.
Unactivated MCM-41 mesoporous silica catalyzes the photodecomposition of chloroform to phosgene and hydrogen chloride under near-UV (λ > 360 nm) irradiation. The rate of photodecomposition increases toward an asymptotic limit as the O2 partial pressure is increased. Deuterochloroform does not decompose under the same experimental conditions. Low concentrations of both cyclohexane and ethanol quench the photodecomposition, whereas water, up to its solubility limit, does not. Dissolved tetraalkylammonium salts suppress photodecomposition. The data are consistent with a mechanism in which light absorption by an SiO2 defect yields an electron-deficient oxygen atom, which then abstracts hydrogen from chloroform. The resulting CCl3 radicals react with oxygen to form a peroxy radical that decomposes, eventually yielding phosgene and hydrogen chloride.
Unmodified MCM-41 silica catalyzes the photodecomposition of chloroform under near-UV irradiation. It is proposed that decomposition is initiated through hydrogen abstraction from chloroform at a photoactive SiO2 defect site.
Cancer is one of the most highlighted topics of current research. Early detection of this disease allows more effective therapy, hence higher chance of cure. Application of fluorescence spectral techniques into oncological diagnostic is one of the potential alternatives. Chemically induced carcinogenesis in rats is widely used model for exploration of various aspects of colorectal cancer. This study shows value of discriminate analysis of urine fluorescent fingerprint between healthy control group of rats and those with dimethylhydrazine induced early lesions of colorectal cancer. Using fluorescence spectroscopy, significant difference (P < 0.05) between both of group was achieved.
Cancer is one of the most highlighted topics of current research. Early detection of this disease allows more effective therapy, hence higher chance of cure. Application of fluorescence spectral techniques into oncological diagnostic is one of the potential alternatives. Chemically induced carcinogenesis in rats is widely used model for exploration of various aspects of colorectal cancer. This study shows value of discriminate analysis of urine fluorescent fingerprint between healthy control group of rats and those with dimethylhydrazine induced early lesions of colorectal cancer. Using fluorescence spectroscopy significant difference (P < 0.05) between both of group was achieved.
A technique is introduced that monitors the depletion of intracellular ground state oxygen concentration ([3O2]) during photodynamic therapy of Mat-LyLu cell monolayers and cell suspensions. The photosensitizer Pd(II) meso-tetra(4-carboxyphenyl)porphine (PdT790) is used to manipulate and indicate intracellular [3O2] in both of the in vitro models. The Stern-Volmer relationship for PdT790 phosphorescence was characterized in suspensions by flowing nitrogen over the suspension while short pulses of 405 nm light were used to excite the sensitizer. The bleaching of sensitizer and the oxygen consumption rate were also measured during continuous exposure of the cell suspension to the 405 nm laser. Photodynamic therapy (PDT) was conducted in both cell suspensions and in cell monolayers under different treatment conditions while the phosphorescence signal was acquired. The intracellular [3O2] during PDT was calculated by using the measured Stern-Volmer relationship and correcting for sensitizer photobleaching. In addition, the amount of oxygen that was consumed during the treatments was calculated. It was found that even at large oxygen consumption rates, cells remain well oxygenated during PDT of cell suspensions. For monolayer treatments it was found that intracellular [3O2] is rapidly depleted over the course of PDT.
This article is protected by copyright. All rights reserved.
We have previously shown that plasmonic nanoparticles conjugated with nuclear-targeting and cytoplasm-targeting peptides (NLS and RGD, respectively) are capable of altering the cell cycle of human oral squamous carcinoma cells (HSC-3). In the present work, we show that this regulation of the cell cycle can be exploited to enhance the efficacy of a common chemotherapeutic agent, 5-Fluorouracil, by pretreating cells with gold nanoparticles. Utilizing flow cytometry cell cycle analysis, we were able to quantify the 5-Fluorouracil efficacy as an accumulation of cells in the S phase with a depletion of cells in the G2/M phase. Two gold nanoparticle sizes were tested in this work; 30 nm with a surface plasmon resonance at 530 nm and 15 nm with a surface plasmon resonance at 520 nm. The 30 nm nuclear-targeted gold nanoparticles (NLS-AuNPs) showed the greatest 5-Fluorouracil efficacy enhancement when 5-Fluorouracil treatment (500 μm, 48 h) is preceded by a 24-h treatment with nanoparticles. In conclusion, we show that nuclear-targeted 30 nm gold nanoparticles enhance 5-Fluorouracil drug efficacy in HSC-3 cells via regulation of the cell cycle, a chemosensitization technique that could potentially be expanded to different cell lines and different chemotherapies.
Gold nanoparticles that target the nucleus of cancer cells have the ability to regulate the cell cycle, causing cells to accumulate in the S phase. A common chemotherapeutic agent, 5-Fluorouracil, is most effective at inducing cell death when cells are in the S phase of the cell cycle. Therefore, treatment with 5-Fluorouracil is preceded by treatment with nuclear-targeting gold nanoparticles to allow for an enhanced S phase population, resulting in enhanced drug efficacy (i.e. chemosensitization).
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50450F, Paper
Loredana Latterini, Luigi Tarpani Fluorescein has been covalently entrapped into 120 nm silica beads in order to measure the effect of plasmonic gold nanoparticles, having 25 nm diameter, on the radiative processes of the... The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Accepted Manuscript DOI: 10.1039/C3PP50399B, Paper
Virginia Helena Albarracin, Julian Simon, Gopal Pathak, Lorena Valle, Thierry Douki, Jean Cadet, Claudio Dario Borsarelli, Maria Eugenia Farias, Wolfgang Gartner UV-resistant Acinetobacter sp. Ver3 isolated from High-Altitude Andean Lakes (HAAL) in Argentinean Puna, one of the highest UV exposed ecosystems on Earth, showed efficient DNA photorepairing ability, coupled to highly... The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50438G, Paper
Madalena M. Reimao-Pinto, Ana Cordeiro, Carina Almeida, Andre V. Pinheiro, Artur Moro, Joao C. Lima, Pedro V. Baptista Spatial and temporal control of molecular mechanisms can be achieved using photolabile bonds that connect biomolecules to protective caging groups, which can be cleaved upon irradiation of a specific wavelength, releasing the biomolecule ready-to-use. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50411E, Paper
Ya-Fang Sun, Jin-Guo Xu, Kun Tang, Dan Miao, Wolfgang Gartner, Hugo Scheer, Kai-Hong Zhao, Ming Zhou Novel orange fluorescent proteins are formed in E. coli, due to the capability of GAF domains to be chromophorylated with phycoerythrobilin. The strong brightness of these constructs makes them promising as biomarkers. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Laboratory studies suggest that evening light before bedtime can suppress melatonin. Here, we measured the range of evening light intensity people can generate with their household lights, and for the first time determined if varying home light before usual bedtime can shift circadian phase. This was a 3-week study with two counterbalanced conditions separated by a 5-day break. In a dim week, eight healthy subjects minimized their home light exposure from 4 h before habitual bedtime until a self-selected bedtime. In a bright week, the subjects maximized their home lighting for the same time. The dim light melatonin onset (DLMO) was assessed after each week. On average subjects maximized their lights to approximately 65 lux and minimized their lights to approximately 3 lux. Wrist actigraphy indicated that subjects went to bed slightly later when lights were maximized (average 14 min later, P = 0.05), but wake time did not change. Every subject had a later DLMO after the week of maximum versus minimum light exposure (average 1:03 h later, P < 0.001). These results demonstrate that the light intensity people can generate at home in the few hours before habitual bedtime can alter circadian timing. People should reduce their evening light exposure to lessen circadian misalignment.
After sunset, we often turn on our lights at home. In this field study, we found that maximizing evening light at home in the 4 h before usual bedtime, delayed the dim light melatonin rhythm by about 1 h, when compared to dim light in the evening. These results highlight that evening light at home can delay central circadian timing and contribute to circadian misalignment.
Tissue engineered skin grafts that mimic the native extracellular matrix of skin has gained huge popularity among clinicians since they increase the survival rate of the patients. Phototherapy shows promising results with respect to acute and chronic pain relief, treatment of inflammatory conditions and promotion of wound healing. Here, we encapsulated a photosensitive polymer poly (3-hexylthiophene) (P3HT) and epidermal growth factor in the core–shell-structured Gelatin/poly(L-lactic acid)-co-poly-(ε-caprolactone) nanofibers [Gel/PLLCL/P3GF(cs)] by coaxial spinning and studied the potential application of the Gel/PLLCL/P3GF(cs) nanofibrous scaffold as a novel skin graft. The proliferation of fibroblasts was significantly improved on Gel/PLLCL/P3GF(cs) under light stimulation compared to fibroblasts on the same scaffold under dark condition. Studies on the in vitro wound healing ability of Gel/PLLCL/P3GF(cs) showed complete closure of wound after 9 days under “light stimulation” too. Furthermore, the potential of adipose-derived stem cells (ASCs) to differentiate to epidermal cells on Gel/PLLCL/P3GF(cs) was evaluated. The differentiated ASCs with keratinocytes morphology were only found on the light stimulated Gel/PLLCL/P3GF(cs). Our results suggest that the photosensitive core–shell Gel/PLLCL/P3GF(cs) nanofibers could be a novel substrate to aid in the reestablishment of skin architecture.
A photosensitive polymer, namely, poly (3-hexylthiophene) is encapsulated within the core–shell-structured Gel/PLLCL fibers by coaxial electrospinning. The proliferation of human dermal fibroblasts was significantly improved on the core–shell nanofibers under light stimulation compared to fibroblasts on the same scaffold under nonstimulated condition. Moreover, the stem cells on the photosensitive scaffolds under light stimulation were more likely to differentiate into epidermal lineages compared to cells without stimulation. Our results suggest that the photosensitive core–shell nanofibers can serve as a novel substrate to promote skin regeneration.
Minimizing exposure to ultraviolet (UV) radiation is an essential component of skin cancer prevention. Providing and using natural and built shade is an effective protection measure against harmful UV. This article describes the factors that must be addressed to ensure quality, effective, well-designed shade and recommends best practice approaches to improving the protection factor (PF) of shade structures. It identifies examples of interventions to increase shade availability and use, and examples of effective shade based on measured protection factors or measured reductions in UV exposures. Finally, this article considers examples of best practice for undertaking shade audits. The article is based on refereed articles and reviews, reports, conference papers and shade practice and policies from reports and on web sites. Articles for the Australian setting are considered first, followed by those in an international setting.
Providing and using natural and built shade is an effective protection measure against harmful UV. This article describes the factors that must be addressed to ensure quality, effective, well-designed shade and recommends best practice approaches to improving the protection factor of shade structures. It identifies examples of interventions to increase shade availability and use, and examples of effective shade based on measured protection factors or measured reductions in UV exposures. Finally, this article considers examples of best practice for undertaking shade audits.
Terrestrial solar ultraviolet (UV) radiation has significant implications for human health and increasing levels are a key concern regarding the impact of climate change. Monitoring solar UV radiation at the earth's surface is therefore of increasing importance. A new prototype portable CCD (charge-coupled device) spectrometer based system has been developed that monitors UV radiation (280-400 nm) levels at the earth's surface. It has the ability to deliver this information to the public in real-time. Since the instrument can operate autonomously, it is called the Autonomous Portable Solar Ultraviolet Spectroradiometer (APSUS). This instrument incorporates an Ocean Optics QE65000 spectrometer which is contained within a robust environmental housing. The APSUS system can gather reliable solar UV spectral data from approximately April to October inclusive (depending on ambient temperature) in the UK. In this paper the new APSUS unit and APSUS system are presented. Example solar UV spectra and diurnal UV Index values as measured by the APSUS system in London and Weymouth in the UK in summer 2012 are shown.
This article is protected by copyright. All rights reserved.
The photo-dynamics of the recombinant rhodopsin fragment of the histidine kinase rhodopsin HKR1 from Chlamydomonas reinhardtii was studied by absorption and fluorescence spectroscopy. The retinal cofactor of HKR1 exists in two Schiff base forms RetA and RetB. RetA is the deprotonated 13-cis retinal Schiff base absorbing in the UVA spectral region. RetB is the protonated all-trans retinal Schiff base absorbing in the blue spectral region. Blue light exposure converts RetB fully to RetA. UVA light exposure converts RetA to RetB and RetB to RetA giving a mixture determined by their absorption cross-sections and their conversion efficiencies. The quantum efficiencies of conversion of RetA to RetB and RetB to RetA were determined to be 0.096±0.005 and 0.405±0.01, respectively. In the dark thermal equilibration between RetA and RetB with dominant RetA content occurred with a time constant of about 3 days at room temperature. The fluorescence emission behavior of RetA and RetB was studied, and fluorescence quantum yields of ϕF(RetA) = 0.00117 and ϕF(RetB) = 9.4×10-5 were determined. Reaction coordinate schemes of the photo-dynamics are developed.
This article is protected by copyright. All rights reserved.
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50348H, Paper
Maria-Antonia Serrano, Javier Canada, Juan Carlos Moreno, Gonzalo Gurrea The aim of this paper is to measure UV exposure for three groups of amateur athletes in their training/recreational schedules using VioSpor personal dosimeters and we found that two of these groups exceeded the international UV threshold level for non-sun-adapted Mediterranean skin. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50429H, Paper
Naoya Ikuta, Shin-ya Takizawa, Shigeru Murata We report a novel system of visible-light-driven CO2 reduction to CO in an aqueous solution, in which DPPC vesicles dispersed in the solution act as a photocatalyst using ascorbate (HAsc-) as an electron source. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50408E, Paper
M. A. Pereira, M. A. F. Faustino, J. P. C. Tome, M. G. P. M. S. Neves, A. C. Tome, J. A. S. Cavaleiro, A. Cunha, A. Almeida The chemical composition of the external structures has a stronger effect on PDI efficiency than complexity and number of layers of the external coating. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,595-602 DOI: 10.1039/C3PP50325A, Paper
Silvia Cristina Nunez, Aguinaldo Silva Garcez, Ilka Tiemy Kato, Tania Mateus Yoshimura, Laercio Gomes, Mauricio Silva Baptista, Martha Simoes Ribeiro Methylene blue photodynamic activity against bacteria is significantly affected by the ionic strength of the medium represented by water (yellow) and 0.9% saline solution (green). The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50195G, Paper
Joana Almeida, Joao P. C. Tome, Maria G. P. M. S. Neves, Augusto C. Tome, Jose A. S. Cavaleiro, Angela Cunha, Liliana Costa, Maria A. F. Faustino, Adelaide Almeida Photodynamic inactivation of MRD bacteria in hospital wastewater is faster than in buffered solutions. Antibiotics present in hospital wastewaters may enhance PDI. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50315A, Communication
C. Riou, C. A. Calliste, A. Da Silva, D. Guillaumot, O. Rezazgui, V. Sol, S. Leroy-Lhez The potential killer effect of four porphyrins was evaluated. Biological results were correlated with photophysical properties and reactive oxygen species production capacity of tested compounds. Surprisingly, the anionic free-base porphyrin showed the strongest phototoxic effect. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Abhishek D. Garg, Patrizia Agostinis Few, selected anticancer therapeutic regimens like Hypericin-PDT are able to induce a promising kind of cancer cell demise called immunogenic cell death (ICD), which can activate the immune system owing to the spatiotemporally defined emission of danger signals. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50290B, Paper
Gabriela Niculae, Ioana Lacatusu, Nicoleta Badea, Raluca Stan, Bogdan Stefan Vasile, Aurelia Meghea Rice bran and raspberry oil-based nanocarriers with antioxidant and anti-UV properties have a less ordered lipid arrangement and high entrapment efficiencies. Advanced sunscreens with broad antioxidant, photoprotective and co-release effectiveness were developed. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,548-562 DOI: 10.1039/C3PP50404B, Paper
Bjorn Finkler, Christian Spies, Michael Vester, Frederick Walte, Kathrin Omlor, Iris Riemann, Manuel Zimmer, Frank Stracke, Markus Gerhards, Gregor Jung Five new "super"-photoacids with enhanced photostability have been developed on the basis of HPTS. Live cell experiments point to their wide use in fluorescence microscopy. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,574-582 DOI: 10.1039/C3PP50394A, Paper
Xiaohong Shang, Ning Wan, Deming Han, Gang Zhang A series of heteroleptic iridium(III) complexes have been theoretically investigated on their electronic structures, photophysical properties, and the phosphorescent efficiency mechanism. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50346A, Paper
Waqar Ahmad, Lijuan Zhang, Yunshan Zhou A newly prepared series of four isostructural mononuclear lanthanide complexes [Ln(HPDH)3(H2O)3][middle dot]H2O has been characterized and their luminescent properties for sensing the guest molecules are investigated. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,488-491 DOI: 10.1039/C3PP50396H, Communication
Pooja Jindal, Rimpy Bhatia, Sadhika Khullar, Sanjay K. Mandal, Ramesh C. Kamboj The synthesis of angular pyrano[2,3-c]chromen-2(3H)-ones (2) through the intramolecular Paterno-Buchi reaction of the acetylenic group with the carbonyl centre in 3-(prop-2-ynyloxy)-4H-chromen-4-ones (1) has been described. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,603-612 DOI: 10.1039/C3PP50374G, Paper
Florencia Gillanders, Luciana Giordano, Sebastian A. Diaz, Thomas M. Jovin, Elizabeth A. Jares-Erijman Photoswitchable fluorescent diarylethenes with extremely electron-donating substituents exhibit reversible photoactivatable, red-shifted emission and significant solvatochromism. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,531-540 DOI: 10.1039/C3PP50351H, Paper
Anand Venkataraman, Daniel J. Coleman, Daniel J. Nevrivy, Tulley Long, Chrissa Kioussi, Arup K. Indra, Mark Leid Exposure to an acute dose of UVB radiation leads to dramatic increase in expression of the Grasp transcript, and Grasp-null mice exhibit disrupted homeostatic responses to UVB exposure. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,563-573 DOI: 10.1039/C3PP50385B, Paper
Krzysztof Komodzinski, Jolanta Lepczynska, Zofia Gdaniec, Libero Bartolotti, Bernard Delley, Stefan Franzen, Bohdan Skalski The photochemistry of 6-amino-2-azidopurine, 2-amino-6-azidopurine and 2,6-diazidopurine ribonucleosides has been investigated in aqueous solutions under aerobic and anaerobic conditions. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,583-594 DOI: 10.1039/C3PP50319D, Paper
Malinee Promkatkaew, Songwut Suramitr, Thitinun Karpkird, Supason Wanichwecharungruang, Masahiro Ehara, Supa Hannongbua The para-hydroxy derivative is an excellent UV absorber based on its broad absorption in the UVB/UVA regions, less emission, and higher photostability compared with others. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, Advance Article DOI: 10.1039/C3PP50343G, Paper
Bowen Wang, Jinliang Yang, Jun Nie, Xiaoqun Zhu A new photocoinitiator, PhBDO, was synthesized and could be used as an effective coinitiator, like BDO, in a BP/acrylate system. The phenyl-oxygen bond would be cleaved after irradiation and produce a PhBDO-derived phenyl radical. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
Light-dark cycles are considered important cues to entrain biological clocks. A feedback loop of clock gene transcription and translation is the molecular basis underlying the mechanism of both central and peripheral clocks. Xenopus laevis embryonic melanophores respond to light with melanin granule dispersion, response possibly mediated by the photopigment melanopsin. In order to test whether light modulates clock gene expression in Xenopus melanophores, we used qPCR to evaluate the relative mRNA levels of Per1, Per2, Clock and Bmal1 in cultured melanophores exposed to light-dark (LD) cycle or constant darkness (DD). LD cycles elicited temporal changes in the expression of Per1, Per2 and Bmal1. A 10-min pulse of blue light was able to increase the expression of Per1 and Per2. Red light had no effect on the expression of these clock genes. These data suggest the participation of a blue-wavelength sensitive pigment in the light-dark cycle-mediated oscillation of the endogenous clock. Our results add an important contribution to the emerging field of peripheral clocks, which in non-mammalian vertebrates have been mostly studied in Drosophila and Danio rerio. Within this context, we show that Xenopus laevis melanophores, which have already led to melanopsin discovery, represent an ideal model to understanding circadian rhythms.
This article is protected by copyright. All rights reserved.
Photochem. Photobiol. Sci., 2014, 13,541-547 DOI: 10.1039/C3PP50369K, Paper
Elena V. Eremeeva, Ludmila P. Burakova, Vasilisa V. Krasitskaya, Alexander N. Kudryavtsev, Osamu Shimomura, Ludmila A. Frank A C-terminal hydrogen-bond network is proposed to be important for the stability of photoprotein molecules taking part in the formation of locked protein conformations and isolation of the active site. The content of this RSS Feed (c) The Royal Society of Chemistry
Direct repair of UV-induced DNA lesions represents an elegant method for many organisms to deal with these highly mutagenic and cytotoxic compounds. Although the participating proteins are structurally well investigated, the exact repair mechanism of the photolyase enzymes remains a vivid subject of current research. In this review, we summarize and highlight the recent contributions to this exciting field.
Direct repair of UV-induced DNA lesions represents an elegant method for many organisms to deal with these highly mutagenic and cytotoxic compounds. Although the participating proteins are structurally well investigated, the exact repair mechanism of the photolyase enzymes remains a vivid subject of current research. In this review, we summarize and highlight the recent contributions to this exciting field.
Envenoming induced by Bothrops snakes is characterized by drastic local tissue damage involving hemorrhage, myonecrosis and proeminent inflammatory and hyperalgesic response. The most effective treatment is antivenom therapy, which is ineffective in neutralizing the local response. Herein, it was evaluated the effectiveness of light-emitting diode (LED) at wavelengths of 635 and 945 nm in reducing inflammatory hyperalgesia induced by Bothrops moojeni venom (BmV) in mice, produced by an subplantar injection of BmV (1 μg). Mechanical hyperalgesia and allodynia were assessed by von Frey filaments at 1, 3, 6 and 24 h after venom injection. The site of BmV injection (1.2 cm2) was irradiated by LEDs at 30 min and 3 h after venom inoculation. Both 635 nm (110 mW, fluence of 3.76 J/cm2 and 41 s of irradiation time) and 945 nm (120 mW, fluence of 3.8 J/cm2 and 38 s of irradiation time) LED inhibited mechanical allodynia and hyperalgesia of mice alone or in combination with antivenom treatment, even when the symptoms were already present. The effect of phototherapy in reducing local pain induced by BmV should be considered as a novel therapeutic tool for the treatment of local symptoms induced after bothropic snake bites.
The effectiveness of LED at wavelengths of 635 and 945 nm, in reducing mechanical inflammatory hyperalgesia and allodynia induced by Bothrops moojeni venom (BmV) in mice, produced by a subplantar injection of BmV (1 μg) was evaluated at 1, 3, 6 and 24 h after BmV injection. The site of BmV injection (1.2 cm2) was irradiated by LEDs at 30 min and 3 h after BmV inoculation. Both 635 and 945 nm LED inhibited mechanical allodynia and hyperalgesia of mice alone or in combination with antivenom treatment, even when the symptoms were already present.
This study compared biological responses of normal human fibroblasts (NHF1) to three sources of ultraviolet radiation (UVR), emitting UVC wavelengths, UVB wavelengths, or a combination of UVA and UVB (solar simulator; emission spectrum, 94.3% UVA and 5.7% UVB). The endpoints measured were cytotoxicity, intra-S checkpoint activation, inhibition of DNA replication and mutagenicity. Results show that the magnitude of each response to the indicated radiation sources was best predicted by the density of DNA cyclobutane pyrimidine dimers (CPD). The density of 6-4 pyrimidine–pyrimidone photoproducts was highest in DNA from UVC-irradiated cells (14% of CPD) as compared to those exposed to UVB (11%) or UVA–UVB (7%). The solar simulator source, under the experimental conditions described here, did not induce the formation of 8-oxo-7,8-dihydroguanine in NHF1 above background levels. Taken together, these results suggest that CPD play a dominant role in DNA damage responses and highlight the importance of using endogenous biomarkers to compare and report biological effects induced by different sources of UVR.
Exposure to UV, including the more energetic wavelengths present in sunlight (UVB), leads to the formation of DNA photoproducts. Among these, the cyclobutane pyrimidine dimers (CPD) are the most abundant. CPD density in DNA of diploid human fibroblasts irradiated with three different UV irradiation sources correlated best with the measured biological outcomes.
Solar light leads to thymine dimers that are mutagenic and primary cause of skin cancer. Here, we report absorption and synchrotron radiation circular dichroism (CD) spectra of Tn single strands with different number n of bases (n =2–7, 10, 11) recorded after various 254 nm irradiation times. From a principal component analysis of the CD spectra, we extract fingerprint spectra of both the cyclobutane pyrimidine dimer (CPD) and the pyrimidine (6-4) pyrimidone photoadduct (64PP). Extending the CD measurements to the vacuum ultraviolet region in combination with systematic examinations of size effects is a new approach to gain insight on the dimeric photoproducts. We find a simple linear correlation between n and average number of dimers formed after 1 h of irradiation. The probability for a thymine to engage in a dimer increases from 32% for n =2 to 41% for n =11, which implies limited effects of terminal thymines, i.e., the reaction does not occur preferentially at the extremities of the single strands as previously stated. It is even possible to form two dimers with only two bridging thymines. Finally, experiments conducted on calf thymus DNA provided a similar signature of the photodimer, but differences are also evident.
Solar light causes mutagenic photodimers. Here we provide synchrotron radiation circular dichroism spectra of the photodimers, and we find that the yield of photodimers in thymine single strands increases linearly with the length. On average two are formed for strands with ten thymine bases.
Polymeric carriers are extensively used in photodynamic therapy (PDT) for increase of efficacy of photosensitizers. Here, we report the influence of nine Pluronic copolymers on phototoxicity of chlorin e6 (Ce6), in particular 5- to 7-fold rise in the phototoxicity caused by hydrophilic Pluronics F127, F108, F68 and F87 and practically no influence on Ce6 of more hydrophobic polymers. The revealed value of 0.2 mg mL−1 of Pluronic F127 concentration sufficient for half-of-maximal increase of Ce6 photodynamic activity proved to be close to 0.16 mg mL−1 inherent in well-documented carrier poly(N-vinylpyrrolidone) (PVP). The dissociation constants of Ce6 complexes with Pluronic F127 and PVP that were estimated from UV spectra were 0.252 and 0.036 mg mL−1, respectively, indicating higher stability of Ce6 complex with PVP. According to the results of 1H-NMR studies of Ce6 complexes, the porphyrin interacts not only with hydrophobic regions but also with hydrophilic sides of both polymers.
Non-covalent binding of Chlorin e6 to hydrophilic polymers results in 5–7-fold enhancement of its phototoxicity in vitro.
The synthetic IgG-binding domain (Z domain) of staphylococcal protein A catalyzes the oxidation of coelenterazine to emit light like a coelenterazine-utilizing luciferase. The Z domain derivatives (ZZ-gCys, Z-gCys and Z-domain) were purified and the luminescence properties were characterized by comparing with coelenterazine-utilizing luciferases, including Renilla luciferase, Gaussia luciferase and the catalytic 19 kDa protein of Oplophorus luciferase. Three Z domain derivatives showed luminescence activity with coelenterazine and the order of the initial maximum intensity of luminescence was ZZ-gCys (100%) > Z-gCys (36.8%) > Z-domain (1.1%) > bovine serum albumin (BSA; 0.9%) > staphylococcal protein A (0.1%) and the background value of coelenterazine (0.1%) in our conditions. The luminescence properties of ZZ-gCys showed the similarity to that of Gaussia luciferase, including the luminescence pattern, the emission spectrum, the stimulation by halogen ions and nonionic detergents and the substrate specificity for coelenterazine analogues. In contrast, the luminescence properties of Z-gCys were close to the catalytic 19 kDa protein of Oplophorus luciferase. The catalytic region of the Z domain for the luminescence reaction might be different from the IgG-binding region of the Z domain.
The synthetic IgG-binding domain (Z domain) of staphylococcal protein A catalyzes the oxidation of coelenterazine to emit light like a coelenterazine-utilizing luciferase. The catalytic properties of the Z domain and the dimmer of Z domain are close to the Oplophorus luciferase and Gaussia luciferase, respectively.
Photochem. Photobiol. Sci., 2014, 13,521-530 DOI: 10.1039/C3PP50267H, Paper
Anna Maria Siani, Giuseppe R. Casale, Sarah Modesti, Alfio V. Parisi, Alfredo Colosimo UV exposure has both positive and harmful biological effects. Consequently it is important to assess personal exposures through dosimetry. The advantages and limitations of dosimetric techniques need to be known adequately to make proper use of past and future data. The content of this RSS Feed (c) The Royal Society of Chemistry
Photochem. Photobiol. Sci., 2014, 13,499-508 DOI: 10.1039/C3PP50307K, Paper
Zsombor Miskolczy, Jozsef G. Harangozo, Laszlo Biczok, Veronique Wintgens, Cedric Lorthioir, Catherine Amiel The inclusion of 6-methoxy-1-methylquinolinium in cucurbituril decelerates electron transfer but does not affect torsional isomerization. The content of this RSS Feed (c) The Royal Society of Chemistry
The dark and photosensitized effects of alloimperatorin methyl ether 1 (hereafter simply alloimperatorin) and its photooxygenation product alloimperatorin hydroperoxide 2 were investigated on human erythrocytes. The results reveal that the furocoumarin 1 photosensitizes efficiently the hemolysis of erythrocytes. The rate of photohemolysis increases on raising the temperature of the postirradiated incubation from 4°C to 37°C. Thermal activation of the photohemolysis and inhibition by 2,6-di-tert-butyl-p-cresol (BHT) suggest that the furocoumarin 1 photosensitizes lipid peroxidation, increasing permeability in the erythrocyte membrane. The hydroperoxide 2 induces dark and photosensitized hemolysis more efficiently than the furocoumarin 1. The rate of hemolysis induced by 2 increases with the incubation temperature and decreases in the presence of tert-butanol and BHT. The hydroperoxide 2 photosensitizes the formation of lipid peroxidation products as shown by the reaction with thiobarbituric acid. This process is diminished by BHT. Our data imply that the photohemolysis sensitized by the furocoumarin 1 is caused by the in situ-formed photooxygenation product 2. Such hydroperoxides are potent hemolytic agents in the dark and especially on photosensitization.
The alloimperatorin 1 photosensitizes efficiently the hemolysis of erythrocytes (panel A). The rate of photohemolysis increases on raising the temperature of the post-irradiated incubation from 4°C to 37°C. Alloimperatorin 1 is autophotooxidized forming its hydroperoxide 2. The hydroperoxide 2 induces dark and photosensitized hemolysis more efficiently (panel B) than 1, and photosensitizes the formation of lipid-peroxidation products in erythrocytes. These processes are inhibited by tert-butanol and 2,6-di-tert-butyl-p-cresol. Our data imply that the photohemolysis sensitized by the alloimperatorin 1 is caused by the in-situ-formed hydroperoxide 2.
This research describes the development and evaluation of the accuracy and precision of an Android app specifically designed, written and installed on a smartphone for detecting and quantifying incident solar UVA radiation and subsequently, aerosol optical depth at 340 and 380 nm. Earlier studies demonstrated that a smartphone image sensor can detect UVA radiation and the responsivity can be calibrated to measured direct solar irradiance. This current research provides the data collection, calibration, processing, calculations and display all on a smartphone. A very strong coefficient of determination of 0.98 was achieved when the digital response was recalibrated and compared to the Microtops sun photometer direct UVA irradiance observations. The mean percentage discrepancy for derived direct solar irradiance was only 4% and 6% for observations at 380 and 340 nm, respectively, lessening with decreasing solar zenith angle. An 8% mean percent difference discrepancy was observed when comparing aerosol optical depth, also decreasing as solar zenith angle decreases. The results indicate that a specifically designed Android app linking and using a smartphone image sensor, calendar and clock, with additional external narrow bandpass and neutral density filters can be used as a field sensor to evaluate both direct solar UVA irradiance and low aerosol optical depths for areas with low aerosol loads.
The comparison of aerosol optical depth (AOD) at 380 nm derived from an Android app specifically written and calibrated, installed on a LG Optimus L3 smartphone compared to the subsequent readings from a Microtops sun photometer. This close relationship was achieved by calibrating, testing and validating an Android app on clear days at two locations in south east Queensland, Australia.
This study utilized the confocal Raman microspectroscopy (CRM) technique for the first time to investigate the degree of the penetration of toluidine blue-orto (TBO) in artificial caries lesions produced by two distinct caries-inducing models. The dentin specimens (n = 10) were divided into three groups: control, in vitro and in situ. Thereafter, the lesion depth and the demineralization level were evaluated by cross-sectional microhardness (CSMH). CRM mapping across the dentin surface was assessed after the dye application. The CSMH and CRM data were analyzed by t-test and ANOVA, respectively (P < 0.05). The values of the lesion depth and the demineralization areas were higher for in situ samples (P < 0.05). The TBO penetration values (μm) for the control, in vitro and in situ groups were 44.8 ± 5.6, 46.1 ± 4.5 and 51.2 ± 8.5, respectively. There were no statistically significant differences among the groups (P > 0.05). The rate of TBO penetration was detected up to about <50 μm and the demineralization level did not influence the results. These results have showed promising parameters to develop new protocols for deep caries lesions management using photodynamic antimicrobial chemotherapy.
Considering the heterogeneous anatomical features of dentin, the penetration dynamics of photosensitizer (PS) into this substrate has become a faced drawback to establish suitable protocols for PACT. The degree of penetration of PS (toluidine blue ortho) in artificially demineralized dentin produced by two distinct caries-inducing models was investigated using confocal Raman microspectroscopy (CRM) for the first time. The rate of PS penetration was detected up to about ∼50 μm and the demineralization level does not interfere somehow on the magnitude of the results. These findings are relevant to guide new protocols for PACT against dental caries.
Novel multifunctional photosensitizers (MFPSs), 5,10,15-tris(4-N-methylpyridinium)-20-(4-phenylthio)-[21H,23H]-porphine trichloride (PORTH) and 5,10,15-tris(4-N-methylpyridinium)-20-(4-(butyramido-methylcysteinyl)-hydroxyphenyl)-[21H,23H]-porphine trichloride (PORTHE), derived from 5,10,15-Tris(4-methylpyridinium)-20-phenyl-[21H,23H]-porphine trichloride (Sylsens B) and designed for treatment of onychomycosis were characterized and their functionality evaluated. MFPSs should function as nail penetration enhancer and as photosensitizer for photodynamic treatment (PDT) of onychomycosis. Spectrophotometry was used to characterize MFPSs with and without 532 nm continuous-wave 5 mW cm−2 laser light (± argon/mannitol/NaN3). Nail penetration enhancement was screened (pH 5, pH 8) using water uptake in nails and fluorescence microscopy. PDT efficacy was tested (pH 5, ± argon/mannitol/NaN3) in vitro with Trichophyton mentagrophytus microconida (532 nm, 5 mW cm−2). A light-dependent absorbance decrease and fluorescence increase were found, PORTH being less photostable. Argon and mannitol increased PORTH and PORTHE photostability; NaN3 had no effect. PDT (0.6 J cm−2, 2 μm) showed 4.6 log kill for PORTH, 4.4 for Sylsens B and 3.2 for PORTHE (4.1 for 10 μm). Argon increased PORTHE, but decreased PORTH PDT efficacy; NaN3 increased PDT effect of both MFPSs whereas mannitol increased PDT effect of PORTHE only. Similar penetration enhancement effects were observed for PORTH (pH 5 and 8) and PORTHE (pH 8). PORTHE is more photostable, effective under low oxygen conditions and thus realistic candidate for onychomycosis PDT.
Double functionality of a multifunctional photosensitizer when applied the dermatophyte Trichophyton mentagrophytus in the presence of nail material: a nail penetration enhancement function and a function as photosensitizer for green light photodynamic treatment of onychomycosis. The possibility of these compounds to weaken the nail plate is based on their keratolytic capacity, viz. the possibility of SH-containing compounds to chemically reduce the covalent disulphide bonds as present in keratin protein fibers in human nail plates. The cationic part of the novel molecules should be responsible for the desired selective (pH 5) PDT effect when binding (•) to fungal hyphae.
We study the photophysical characters of two oligofluorenes-functionalized anthracenes molecules with different fluorine-vinylene (FV) units, which exhibits that “excimer” state appears in the solution after photoexcitation. The dynamic data shows that two mechanisms are responsible for the generation of “excimer”. The fast one is controlled by the arene-arene interaction between molecules and the slow one is influenced by the diffusion motion of molecules. Increasing the number of FV units may suppress the DM-dependent “excimer” and enhance the yield of intrinsic fluorescence, which finally improves the fluorescence property of molecules in solution.
The “excimer” generation mechanisms of oligofluorenes-functionalized anthracenes molecules with fluorine-vinylene (FV) units in solution were studied. The diffusion of molecule (DM) and arene-arene interaction (A-A I) could be responsible for the formation processes of “excimer”. As the number of FV units increases, the DM-dependent “excimer” generation process could be restrained, but the A-A I dependent formation path may be enhanced. Fortunately, the total optical property of the linear oligofluorenes-functionalized anthracenes molecules could be improved due to the enhancement of intrinsic fluorescence quantum yield as the FV units increase.
Photochem. Photobiol. Sci., 2014, 13,492-498 DOI: 10.1039/C3PP50352F, Paper
Elisabete Oliveira, Rosa M. F. Baptista, Susana P. G. Costa, M. Manuela M. Raposo, Carlos Lodeiro New bis(indolyl)methane derivatives bearing functionalized arylthiophene spacers were synthesised, and their solvatochromic behaviour was explored in the ground and excited states. The content of this RSS Feed (c) The Royal Society of Chemistry
Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the upper hemisphere. The measurements were done in the summer season when solar UV radiation is highest. The selected wavelengths were 307, 350 and 550 nm representing the UVB, UVA and VIS band. Absolute values of radiance differ considerably between the wavelengths. Normalizing the measured values by use of direct solar radiance made the spatial distributions of unequal sky radiance comparable. The results convey a spatial impression of the different distributions of the radiance at the three wavelengths. Relative scattered radiance intensity is one order of magnitude greater in UVB than in VIS, whereas in UVA lies roughly in between. Under slightly overcast conditions scattered radiance is increased at all three wavelengths by about one order of magnitude. These measurements taken at the seaside underline the importance of diffuse scattered radiance. The effect of shading parts of the sky can be estimated from the distribution of sky radiance. This knowledge might be useful for sun seekers and in the treatment of people staying at the seaside for therapeutic purposes.
Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the hemisphere. The measurements were done shortly after the solstice at 307 nm, 350 nm and 550 nm representing UVB, UVA and VIS. Normalizing the measured values by use of direct solar radiation made the spatial distributions of sky radiance comparable. The results convey a spatial impression of the distribution of the radiance. The effect of shading parts of the sky can be estimated from the radiance distribution.
Photochem. Photobiol. Sci., 2014, 13,509-520 DOI: 10.1039/C3PP50314C, Paper
Alessio Cesaretti, Benedetta Carlotti, Catia Clementi, Raimondo Germani, Fausto Elisei The antibiotic tetracycline and its complexes were investigated in confined media that are promising as drug delivery systems. In sol-gel they spread between water pools and hydrophobic domains, where fluorescence is highly enhanced and lifetimes are greatly lengthened. The content of this RSS Feed (c) The Royal Society of Chemistry
The electronic nature of substituents attached to the 4-aryl moiety of 1,4-dihydropyridines strongly affects the photophysical and photochemical behavior of these family of compounds. The presence of an electron donor substituent on the 4-aryl moiety (or the absence of electron-withdrawing ones) modifies the luminescence lifetimes (τ < 100 ps) and diminishes the photodecomposition quantum yields. For electron-withdrawing substituents, the photodegradation quantum yield is affected by the media, changing more than two orders of magnitude as the polarity is increased. Studies in micellar media allow us to conclude that 4-aryl-1,4-dihydropyridines are located near to the interface; however, the surface charge of micelles has no effect on the photodegradation rate constant or the photoproducts profile. The main conclusion of this work is that the photolability of 4-aryl-1,4-dihydropyridines can be significantly reduced by the incorporation of antioxidant moieties.
The electronic nature of substituents attached to the 4-aryl moiety of 1,4-dihydropyridines strongly affect the photophysical and photochemical behavior of these family of compounds. The presence of an electron-donor substituent on the 4-aryl moiety (or the absence of electron-withdrawing ones), diminishes the photodecomposition quantum yields. Studies in micellar media allow us to conclude that 4-aryl-1,4-dihydropyridines are located near to the interface, however the surface charge of micelles has no effect on the photodegradation rate constant or the photoproducts profile. Our main conclusion is that the photolability of 4-aryl-1,4-dihydropyridines can be significantly reduced by the incorporation of antioxidant moieties.
Studies involving metal enhancement effects have gained popularity, and enhancement of fluorescence due to the close proximity of a dye molecule to a metal nanoparticle is well documented. Although enhancement of singlet oxygen production by metal has been reported, studies are relatively scarce and so far only stationary silver island films have been proven to be adequate to do so. Herein, we describe the synthesis and characterization of core–shell nanoparticles on which a photosensitizer acting as source of singlet oxygen has been covalently attached to the nanoparticle surface. As a proof of concept, silver nanoparticles with a diameter around 68 nm were chosen as the metallic core, and were coated by a silica shell of about 22 nm in thickness. The silica shell plays a dual role as a spacer and a medium onto which the photosensitizer, rose bengal (RB), has been covalently attached. These novel core–shell nanoparticles allow for the amplification of singlet oxygen production by 3.8 times, which is similar to the amplification found for RB in proximity of silver island films.
Silver-silica core-shell nanoparticles, on to which rose bengal has been covalently attached to the shell, have been synthesized and conventionally characterized. These novel core-shell nanoparticles allow for an amplification of singlet oxygen production by 3.8 times in aqueous solution.
Zinc complex of pyropheophorbide-b, a derivative of chlorophyll-b, was covalently dimerized through ethylene glycol diester. The synthetic homo-dyad was axially ligated with two methanol molecules from the β-face and both the diastereomerically coordinating methanol species were hydrogen bonded with the keto-carbonyl groups of the neighboring chlorin in a complex. The resulting folded conformer in a solution was confirmed by visible, 1H NMR and IR spectra. All the synthetic zinc chlorin homo- and hetero-dyads consisting of pyropheophorbides-a, b and/or d took the above methanol-locked and π–π stacked supramolecules in 1% (v/v) methanol and benzene to give redmost (Qy) electronic absorption band(s) at longer wavelengths than those of the corresponding monomeric chlorin composites. The other zinc chlorin and bacteriochlorin homo-dyads completely formed similar folded conformers in the same solution, while zinc inverse chlorin and porphyrin homo-dyads partially took such supramolecules. The J-type aggregation to folded conformers and the redshift values of composite Qy bands were dependent on the electronic and steric factors of porphyrinoid moieties in dyads.
Synthetic zinc chlorophyll dyads were intramolecularly folded with two methanol molecules to form their supramolecules by doubly coordinating and hydrogen-bonding. The resulting π−π stacked J-aggregates gave red-shifted Qy bands in a solution.
Despite photocatalytic degradation is studied generally focusing the catalyst, its interaction with the contaminant molecule plays a fundamental role in the efficiency of that process. Then, we proposed a comparative study about the photodegradation of two well-known dyes, with different acidity/basicity – Methylene Blue (MB) and Rhodamine B (RhB), catalyzed by TiO2 nanoparticles, varying both dye and photocatalyst concentrations. The results showed that the amphoteric character of MB molecules, even in a range of concentration of 5.0–10.0 mg L−1, did not imply in pH variation in solution. Therefore, it did not affect the colloidal behavior of TiO2 nanoparticles, independent of the relative dye/catalyst concentration. The acid–base character of RhB influenced the resultant pH of the solution, implicating in different colloidal behavior of the nanoparticles and consequently, in different degradation conditions according to dye concentration. As the isoelectric point of TiO2 is between the pH range of the RhB solutions used in this study, from 1.0 to 7.5 mg L−1, the resultant pH was the key factor for degradation conditions, from a well dispersed to an agglomerated suspension.
Plot presenting the relation between photoinduced RhB photodegradation rate constant (k* = k'/[TiO2]) as a function of TiO2 photocatalyst and Rhodamine B initial concentration.
Weak photon absorption and fast carrier kinetics in graphene restrict its applications in photosensitive reactions. Such restrictions/limitations can be overcome by covalent coupling of another photosensitive nanostructure to graphene, forming graphene-semiconductor nanocomposites. Herein, we report one-pot synthesis of RGO–Ag3VO4 nanocomposites using various sacrificial agents like ethanol, methanol, propanol and ethylene glycol (EG) under visible light illumination. The Raman spectral analysis and 13C MAS NMR suggest ethanol to be the best sacrificial agent among those studied. Thermal analysis studies, further, confirm the stability of the synthesized nanocomposite with ethanol as sacrificial agent. In view of this, the activity toward dye degradation was focused over the composites prepared via ethanol as sacrificial agent. It was observed and proved that cationic dyes could be degraded quantitatively and swiftly compared to anionic dyes (37.79%) in 1.5 h. This suggests that the surface of the nanocomposites is anionic as partial reduction takes place during synthesis process. In case of mixed dye degradation process, it was noticed that the presence of cationic dye doubles the degradation of anionic dye. The activity of these synthesized nanocomposites is more than five-fold toward the phototransformation of phenol and photodegradation of textile dyes under visible light illumination.
One-pot synthesis of RGO–Ag3VO4 nanocomposites using various sacrificial agents like ethanol, methanol, propanol and ethylene glycol (EG) under visible light illumination. The activity of these synthesized nanocomposites is more than five-fold toward the photohydroxylation of phenol and photodegradation of textile dyes under visible light (VISL) illumination.
The marine annelid Chaetopterus variopedatus produces bioluminescence by an unknown and potentially novel mechanism. We have advanced the study of this fascinating phenomenon, which has not been investigated for nearly 60 years after initial studies were first reported for this species. Here, we show that the luminous slime produced by the worm exhibits blue fluorescence that matches the bioluminescence emission. This result suggests that the oxyluciferin emitter is present. However, while the blue fluorescence decays over time green fluorescence is increasingly revealed that is likely associated with products of the luminescence reaction. LC/MS and fluorescence analysis of harvested luminescent material revealed riboflavin as the major green fluorescent component. Riboflavin is usually associated with the mechanism of light production in bacteria, yet luminous bacteria were not found in the worm mucus, and accordingly were not reported to be directly responsible for the light emission, which is under nervous control in the worm. We therefore propose a hypothesis in which riboflavin or a structurally related derivative serves as the emitter in the worm's light producing reaction.
The marine worm Chaetopterus variopedatus produces bioluminescence by an unknown mechanism. We show that the luminous slime produced by the worm exhibits blue fluorescence that matches the bioluminescence emission suggesting that the oxyluciferin emitter is present. As the blue fluorescence decays over time green fluorescence is increasingly revealed. We determined that riboflavin is the major green fluorescent component. It is likely that riboflavin accounts for the green fluorescence observed throughout the worm and we speculate that riboflavin or a structurally related derivative serves as the emitter in the worm's light producing reaction.
UVA-activated psoralens are used to treat hyperproliferative skin conditions due to their ability to form DNA photoadducts, which impair cellular processes and may lead to cell death. Although UVA (320–400 nm) is more commonly used clinically, studies have shown that UVB (280–320 nm) activation of psoralen can also be effective. However, there has been no characterization of UVB-induced adduct formation in DNA alone. As psoralen derivatives have a greater extinction coefficient in the UVB region (11 800 cm−1 M−1 at 300 nm) compared with the UVA region (2016 cm−1 M−1 at 365 nm), a greater extent of adduct formation is expected. SELDI-TOF, a proteomic technique that combines chromatography with mass spectrometry, was used to detect photoadduct formation in an alternating A–T oligonucleotide. 8-Methoxypsoralen (8-MOP) and DNA solutions were irradiated with either UVA or UVB. An adduct peak was obtained with SELDI-TOF. For UVB-activated 8-MOP, the extent of adducts was three times greater than for UVA. HPLC ESI-MS analysis showed that UVB irradiation yielded high levels of 3,4-monoadducts (78% of total adducts). UVA was more effective than UVB at conversion of 4′,5′-monoadducts to crosslinks (17% vs 4%, respectively). This report presents a method for comparing DNA binding efficiencies of interstrand crosslink inducing agents.
Upon irradiation with ultraviolet light, a DNA intercalated 8-Methoxypsoralen (8-MOP) molecule will bind to an adjacent thymine, leading to monoadduct formation. Also shown is a SELDI-TOF MS tracing of an 8-MOP and DNA solution irradiated with 17.7 J cm−2 of UVB. Using an alternating 10 bp adenine and thymine oligonucleotide (3025 m/z), we observed the dose dependent formation of a peak at 3241 m/z, which corresponds to the combined mass of our oligonucleotide and an 8-MOP molecule. This novel protocol provided a rapid modality for assessing the overall binding efficiencies and stoichiometries of psoralen derivatives upon irradiation in the presence of DNA.
ZnO–SnO2 nanoparticles were prepared by coprecipitation method; then Mg, with different molar ratios and calcination temperatures, was loaded on the coupled nanoparticles by impregnation method. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) techniques. Based on XRD results, the ZnO–SnO2 and Mg/ZnO–SnO2 nanoparticles were made of ZnO and SnO2 nanocrystallites. According to DRS spectra, the band gap energy value of 3.13 and 3.18 eV were obtained for ZnO–SnO2 and Mg/ZnO–SnO2 nanoparticles, respectively. BET analysis revealed a Type III isotherm with a microporous structure and surface area of 32.051 and 49.065 m2 g−1 for ZnO–SnO2 and Mg/ZnO–SnO2, respectively. Also, the spherical shape of nanocrystallites was deduced from TEM and FESEM images. The photocatalytic performance of pure ZnO–SnO2 and Mg/ZnO–SnO2 was analyzed in the photocatalytic removal of methyl orange (MO). The results indicated that Mg/ZnO–SnO2 exhibited superior photocatalytic activity to bare ZnO–SnO2 photocatalyst due to high surface area, increased MO adsorption and larger band gap energy. Maximum photocatalytic activity of Mg/ZnO–SnO2 nanoparticles was obtained with 0.8 mol% Mg and calcination temperature of 350°C.
The coupled and Mg impregnated ZnO–SnO2 nanoparticles were prepared by co-precipitation method with various Mg molar ratios and calcination temperatures. With Mg impregnation, the band gap energy of ZnO–SnO2 nanoparticles increases by 0.05 eV, exhibiting a blue shift. Mg/ZnO–SnO2 nanoparticles indicated a better performance than pure ZnO–SnO2 nanoparticles.
Reaction of excited ketoprofen (KP) with tryptophan (Trp) and tyrosine (Tyr) in a phosphate buffer solution was studied by the transient absorption spectroscopy. Both amino acids, which would interact with KP in bovine serum albumin [Monti, S.  Phys. Chem. Chem. Phys., 11, 9104–9113], accelerated the proton transfer reaction to yield 3-ethylbenzophenone ketyl biradical (EBPH) from KP carbanion, which was produced by photoexcitation of KP− through decarboxylation. By means of the actinometry method with benzophenone, the reaction quantum yield was successfully estimated to be fairly large, and Trp, Tyr, DOPA and 4-methylphenol were found to be a good proton donor for the carbanion. The formation rate constants of EBPH by the amino acids (kr) were also determined to be (2.7 ± 0.1) × 109 M−1s−1 for Trp and (7.8 ± 0.4) × 108 M−1s−1 for Tyr, which were larger than those by basic amino acids and dipeptides reported. The reason for the highly efficient proton transfer reaction with Trp and Tyr would be explained by difference of the activation energy for the reaction. These results suggest that the proton transfer should be a key process for an initial photoreaction of KP with a protein, causing photosensitization in vivo.
Reaction of excited ketoprofen (KP) with tryptophan (Trp) and tyrosine (Tyr) in a phosphate buffer solution was studied by the transient absorption spectroscopy. Both amino acids accelerated the proton transfer reaction to yield 3-ethylbenzophenone ketyl biradical from KP carbanion. The reaction quantum yield was successfully estimated, and Trp and Tyr were found to be a good proton donor. The highly efficient proton transfer reaction can be explained by difference of the activation energy for the reaction. The proton transfer should be a key reaction of KP in a protein, causing photosensitization in vivo.
Nuclear Factor Kappa-B (NF-κB) is a transcription factor that controls expression of genes involved in the immune and inflammatory responses as well as being a key component in the onset of cancers. In this study, we provided evidence that mitogen- and stress-activated protein kinase (MSK1) is responsible for a noncanonical late-phase activation of NF-κB upon UVB irradiation. Our data demonstrated that following UVB irradiation, MSK1 is activated via phosphorylation at the 24 h time point coinciding with translocation of NF-κB into the nucleus. Investigations into the signaling pathways upstream of MSK1 through the use of specific inhibitors for mitogen-activated protein kinase and p38 revealed that both kinases are required for full phosphorylation during the late phase (24 h), while p38 is paramount for phosphorylation during the early phase (6 h). Electromobility shift assays (EMSA) showed that inhibition of MSK1 resulted in a marked reduction in NF-κB binding affinity without altering the nuclear translocation of NF-κB. Supershift EMSA implicate that the p65, but not p50, isoform of NF-κB is involved in late-phase activation in response to UVB irradiation. Together, the results of these studies shed light onto a novel pathway of MSK1-mediated late-phase activation of NF-κB in response to UVB irradiation.
Proposed model of MSK-1mediated NF-κB activation following UVB irradiation: UVB irradiation stimulates the activation of MSK1 via phosphorylation from ERK and p38. During the early-phase response, activation of MSK1 is heavily dependent on the function of p38, as opposed to the late-phase in which p38 and ERK work in a concerted effort to phosphorylate MSK1. Although MSK1 is highly phosphorylated during the early-phase, it is not until UVB has stimulated the translocation of NF-κB into the nucleus of the cell during the late-phase that MSK1 is able to transactivate NF-κB into a fully active form.
Uveal melanoma is the most frequent intraocular cancer and the second most common form of melanoma. It metastasizes in half of the patients and the prognostic is poor. Although ultraviolet (UV) radiation is a proven risk factor for skin melanoma, the role of UV light in the etiology of uveal melanoma is still contradictory. We have compared epidemiological and genetic evidences of the potential role of UV radiation in uveal melanoma with data on cutaneous melanoma. Even though frequently mutated genes in skin melanoma (e.g. BRAF) differ from those found in uveal melanoma (i.e. GNAQ, GNA11), their mutation pattern bears strong similarities. Furthermore, we provide new results showing that RAC1, a gene recently found harboring UV-hallmark mutation in skin melanoma, is also mutated in uveal melanoma. This article aims to review the work done in the last decades to understand the etiology of uveal melanoma and discuss new avenues, which shed some light on the potential role of UV exposure in uveal melanoma.
Uveal melanoma is the most frequent intraocular cancer and the second most common form of melanoma after cutaneous. The evidences are contradictory about the role of ultraviolet (UV) light in the etiology of in uveal melanoma. We have compared epidemiological and genetic evidences of the potential role of UV radiation in uveal melanoma with data on cutaneous melanoma. We have reviewed the work done in the last decades in order to understand the etiology of uveal melanoma and discuss new avenues, which shed some light on the potential role of UV exposure in uveal melanoma.
Vacuum UV (VUV) process is an incipient advanced oxidation process, which can be used for water treatment. This process relies on the formation of hydroxyl radicals through the VUV-induced photolysis of water. In particular, the use of ozone-generating mercury vapor lamps, which emit 10% of the radiation at 185 nm and 90% at 254 nm, is showing very promising results for the degradation of micropollutants. The kinetics of VUV process has been studied in batch- and flow-through reactors, but the effect of 254 and 185 nm photons cannot be isolated, mass transfer resistances can take place and the interpretation of the results is complex. In this technical note, a new VUV collimated beam to conduct kinetic tests is presented, which offers several advantages: (1) it allows the irradiation of samples with 185, 254 nm photons, or both, (2) the concentration of reagents is uniform in the reaction volume and (3) it allows to change the fluence rate by changing the distance between the lamp and the photoreactor. Details of the geometry are presented, as well as an analysis of the collimation and uniformity of the radiation of the new VUV-collimated beam setup.
Vacuum UV (VUV) process is an incipient advanced oxidation process (AOP), which can be used for water treatment. HO radicals are formed through the VUV-induced (185 nm) photolysis of water. Ozone generating mercury vapor lamps, which emit 10% of the radiation at 185 nm and 90% at 254 nm, are usually used for the degradation of micropollutants. Conventional UV-collimated beam setups cannot be used to study VUV processes as oxygen in air absorbs 185 nm photons. In this technical note, a new VUV-collimated beam, which allows the irradiation of samples with 185, 254 nm radiation, or both, is presented.
The effects of π-spacer and electron donor groups on the photophysical behaviors of fluorenone-based linear conjugated oligomers have been systemically investigated. Solvent-dependent steady-state measurements exhibit that the fluorene vinylene (FV) spacer and the electron-donating ability of donor group are able to modulate the spectral features of oligomers and the fluorescence quantum yield could decrease with the increasing of the solvent polarity. Meanwhile, quantum chemical calculation simulates their absorption spectra, and analyzes their electron transition components simultaneously. The transient absorption measurements focus on the photoexcitation dynamics of these oligomers in the toluene solution, which show that an intramolecular charge transfer state exists in the relaxation process of excited states, and its generation process could accelerate with the introduction of FV spacer and the enhancement of donor strength.
Dynamic mechanism of fluorenone-based linear conjugated oligomers.
Assignment of the fluorescence spectrum of firefly luciferin in aqueous solutions was achieved by utilizing not only emission energies but also theoretical absorption spectra and relative concentrations as estimated by pKa values. Calculated Gibbs free energies were utilized to estimate pKa values. These pKa values were then corrected by employing the experimental results. It was previously thought that the main peak near 550 nm observed in the experimental fluorescence spectra at all pH values corresponds to emission from the first excited state of the luciferin dianion [Ando et al. (2010) Jpn. J. Appl. Phys. 49, 117002–117008]. However, we found that the peak near 550 nm at low pH corresponds to emission from the first excited state of the phenolate monoanion of luciferin. Furthermore, we found that the causes of the red fluorescence at pH 1–2 are not only the emission from phenol monoanion but also the emission from the protonated species at nitrogen atom in the thiazoline ring of dianion.
With the help of theoretical pKa values in the first excited states the experimental fluorescence spectra of firefly luciferin and its conjugate acids and bases in solution with various pH values were successfully assigned.
A 2-year field study on the effect of different light environments, obtained by using cladding materials (polyethylene films and shade net) able to cut off specific regions of the photosynthetically active radiation and ultraviolet wavebands, on the growth and phenylpropanoids content of Achillea collina grown in the Alps was conducted. Overall the plant growth was strongly enhanced in the second growing season irrespective of radiation treatment. The light environment did not affect total biomass accumulation, but only carbon allocation to leaves or inflorescences. Indeed the phenylpropanoid levels in inflorescences appeared to be more sensitive to the light environment than leaves as the latter showed high constitutive amounts of these compounds. However, the use of polyethylene films improved to some extent the content of caffeic acid derivatives in leaves. Our results showed that yarrow production, in the alpine situation considered, is influenced by the growing season and the light environment, providing a basis to optimize its quality, depending on the concentration of bioactive compounds, by means of proper agronomic practices.
A 2-year field study on the effect of different light environments, obtained by using cladding materials able to cut off specific regions of the photosynthetically active radiation and ultraviolet wavebands, on the growth and phenylpropanoids content of Achillea collina grown in the Alps was conducted. Plant growth was strongly enhanced in the second growing season irrespective of radiation treatment. Phenylpropanoid levels in inflorescences appeared to be more sensitive to the light environment than leaves as the latter showed high constitutive amounts of these compounds. The use of polyethylene films improved to some extent the content of caffeic acid derivatives in leaves.
The aim of this study was to evaluate the effect of low-level laser therapy (LLLT) on odontoblast-like cells exposed to a bleaching agent. Mouse dental papilla cell-23 cells were seeded in wells of 24-well plates. Eight groups were established according to the exposure to the bleaching agent and LLLT (0, 4, 10 and 15 J cm−2). Enamel–dentin disks were adapted to artificial pulp chambers, which were individually placed in wells containing Dulbecco's modified Eagle's medium (DMEM). A bleaching agent (35% hydrogen peroxide [BA35%HP]) was applied on enamel (15 min) to obtain the extracts (DMEM + BA35%HP components diffused through enamel/dentin disks). The extracts were applied (1 h) to the cells, and then subjected to LLLT. Cell viability (Methyl tetrazolium assay), alkaline phosphatase (ALP) activity, as well as gene expression of ALP, fibronectin (FN) and type I collagen, were evaluated. The bleaching procedures reduced the cell viability, ALP activity and gene expression of dentin proteins. Laser irradiation did not modulate the cell response; except for FN, as LLLT decreased the gene expression of this protein by the cells exposed to the BA35%HP. It can be concluded that BA35%HP decreased the activities of odontoblasts that were not recovered by the irradiation of the damaged cells with low-level laser parameters tested.
The aim of the present study was to evaluate the effect of low-level laser therapy (LLLT) on odontoblast-like cells exposed to a bleaching agent. Eight groups were established according to the exposure to the bleaching agent (35% hydrogen peroxide) and LLLT (0, 4, 10, and 15 J cm−2). The bleaching procedures reduced the cell viability, ALP activity, and gene expression of dentin proteins. Laser irradiation did not modulate the cell response; except for FN, since LLLT decreased the gene expression of this protein by the cells exposed to the 35% hydrogen peroxide.
The effect of intermolecular proton transfer on the spectral properties of levofloxacin in the ground and excited electronic states was studied. The preferred direction of possible protolytic reactions induced by UV irradiation in this compound was studied. It was found that the proton transfer processes have a considerable effect on the capability of the compound to emit light and occur on the nanosecond timescale. The photochemical reactions of the tree forms of levofloxacin (pH: 4.0, 7.0, 10.0) were studied by laser flash photolysis and product studies. Irradiation at pH 4 yielded a pulse and transient (λmax = 395, 515, 575 nm) assigned to the protonated triplet. Irradiation at pH 7 yielded a transient species (λmax = 525, 610 nm) assigned to the neutral form. Protonation of the anionic singlet excited state was also observed (λmax = 440, 570, 680 nm).
The preferred direction of possible protolytic reactions induced by UV irradiation in fluoroquinolones at different pH of solutions was studied. It was found that the proton transfer processes have a considerable effect on the capability of the compound to emit light and occur on the nanosecond timescale. The photochemical reactions of the three protolytic forms of levofloxacin were studied by laser flash photolysis.
Singlet oxygen (1O2) is of special interest in plant stress physiology. Studies focused on internal, chlorophyll-mediated production are often complemented with the use of artificial 1O2 photosensitizers. Here, we report a comparative study on the effects of Rose Bengal (RB), Methylene Violet (MVI), Neutral Red (NR) and Indigo Carmine (IC). These were infiltrated into tobacco leaves at concentrations generating the same fluxes of 1O2 in solution. Following green light-induced 1O2 production from these dyes, leaf photosynthesis was characterized by Photosystem (PS) II and PSI electron transport and oxidative damage was monitored as degradation of D1, a PSII core protein. Cellular localizations were identified on the basis of the dyes’ fluorescence using confocal laser scanning microscopy. We found that RB and NR were both localized in chloroplasts but the latter had very little effect, probably due to its pH-dependent photosensitizing. Both RB and intracellular, nonplastid MVI decreased PSII electron transport, but the effect of RB was stronger than that of MVI and only RB was capable of damaging the D1 protein. Intercellularly localized IC had no significant effect. Our results also suggest caution when using RB as photosensitizer because it affects PSII electron transport.
Confocal microscopy imaging of tobacco leaf cells loaded with the photosensitizer Rose Bengal. Composite image shows Rose Bengal fluorescence as green and chlorophyll fluorescence as red.
Four kinds of luminescent hybrid soft gels have been assembled by introducing the lanthanide (Eu3+, Tb3+) tetrakis β-diketonate into the covalently bonded imidazolium-based silica through electrostatic interactions. Here, the imidazolium-based silica matrices are prepared from imidazolium-derived organotriethoxysilanes by the sol–gel process, in which the imidazolium cations are strongly anchored within the silica matrices while anions can still be exchanged following application for functionalization of lanthanide complexes. The photoluminescence measurements indicated that these hybrid soft gels exhibit characteristic red and green luminescence originating from the corresponding ternary lanthanide ions (Eu3+, Tb3+). Further investigation of photophysical properties reveals that these soft gels have inherited the outstanding luminescent properties from the lanthanide tetrakis β-diketonate complexes such as strong luminescence intensities, long lifetimes and high luminescence quantum efficiencies.
Ternary lanthanide luminescent hybrid soft gels Gel-Im+[LaL4]− were prepared by linking the europium/terbium tetrakis β-diketonate complexes into the silicon framework, which provides a representative method to assemble lanthanide-functionalized porous materials with chemical bonds.
Thai traditional medicine employs a wide range of indigenous herbs in the forms of tincture or tea for the cure of skin and systemic inflammatory diseases. The protection by Thai plants extracts against UVB DNA damage and cytotoxicity was investigated in human keratinocytes. Petroleum ether, dichloromethane and ethanol extracts were prepared from 15 Thai herb species, and the total phenolic and flavonoid contents, the antioxidant and UV-absorbing properties were assessed by standard procedures. Cytoprotective effects were evaluated on the basis of cell survival, caspase-3 activity and pyrimidine dimers determination. High total phenolic and flavonoid contents were found in the ethanol and dichloromethane fractions. Dichloromethane extract of turmeric was shown to possess the highest antioxidant activity. The maximum UV absorptions were found in the ethanol extract of turmeric and in the dichloromethane extract of ginger. These extracts stimulated the synthesis of Thioredoxin 1, an antioxidant protein, and could protect human HaCaT keratinocytes from UV-induced DNA damage and cytotoxicity. The present data support the utilization of turmeric and ginger extracts in anti-UV cosmetic pharmaceuticals.
The protection by Thai plants extracts against UVB DNA damage and cytotoxicity was investigated in human keratinocytes. Ethanol extract of turmeric and dichloromethane extract of ginger were shown to possess the maximum UV absorptions (a). These extracts stimulated the synthesis of Thioredoxin 1, an antioxidant protein (b), and could protect human HaCaT keratinocytes exposed to UVB from DNA damage (d) and caspase-3-mediated apoptosis (c). The present data support the utilization of turmeric and ginger extracts in anti-UV cosmetic pharmaceuticals.
In this work, we use the effect of herbicides that affect the photosynthetic chain at defined sites in the photosynthetic reaction steps to derive information about the fluorescence emission of photosystems. The interpretation of spectral data from treated and control plants, after correction for light reabsorption processes, allowed us to elucidate current controversies in the subject. Results were compatible with the fact that a nonnegligible Photosystem I contribution to chlorophyll fluorescence in plants at room temperature does exist. In another aspect, variable and nonvariable chlorophyll fluorescence were comparatively tested as bioindicators for detection of both herbicides in aquatic environment. Both methodologies were appropriate tools for this purpose. However, they showed better sensitivity for pollutants disconnecting Photosystem II–Photosystem I by blocking the electron transport between them as Atrazine. Specifically, changes in the (experimental and corrected by light reabsorption) red to far red fluorescence ratio, in the maximum photochemical quantum yield and in the quantum efficiency of Photosytem II for increasing concentrations of herbicides have been measured and compared. The most sensitive bioindicator for both herbicides was the quantum efficiency of Photosystem II.
In this work we use the effect of herbicides at defined sites in the photosynthetic chain to derive information about the fluorescence emission of photosystems. Additionally, chlorophyll fluorescence was tested as a bioindicator for detection of both herbicides in aquatic environment.