Journal of Photochemistry and Photobiology最新文献

Heterojunction formation is among the important approaches to improve visible light activity of photocatalysts, to achieve cheaper and more sustainable pollutant removal, at larger scale. In this study, Bi₂WO₆ NS/x% CuFe₂O₄ NF (x = 1, 2, 5 and 10) composites were prepared using electrospinning and hydrothermal synthesis, to achieve improved photocatalytic Cr (VI) removal under visible light. The effects of the composite formation on their structural, optical and photocatalytic properties were studied. Pure CuFe₂O₄ and Bi₂WO₆ phases were achieved, as reflected by X-ray diffraction (XRD) analysis, with some variations in peak parameters in the Bi₂WO₆ NS/CuFe₂O₄ NF composites, which confirmed the incorporation of the CuFe₂O₄ NFs into the Bi₂WO₄ NS. From photoluminescence studies, lower emission peaks were observed in the Bi₂WO₆ NS/CuFe₂O₄ NF composites than that in pure Bi₂WO₆ NS, indicating the achievement of suppressed recombination of charge carriers in the composites. Hence, Cr (VI) removal rate was significantly improved with the Bi₂WO₄ NS/ CuFe₂O₄ NF composite formation, where each of them shows higher activity than both Bi₂WO₆ NS and CuFe₂O₄ NF. The highest removal rates of 90.35% and 96.04% were achieved with the sample Bi₂WO₄ NS/2% CuFe₂O₄ NF, after 60 and 120 min of visible light irradiations respectively.

Modern high-performance photodetector research is driven by the need to simultaneously improve multiple parameters, but also fit the decreasing size of electronics and maintain low production price.  Here, we demonstrated how our synthesized ZnO tetrapod (ZnO-T) nanostructure was deposited on electrodes with variating gap by four coating methods including drop casting, microdrop casting, spray coating and slot-die coating with the same thickness. Optimizing the inter-electrode gap and coating method the record I_UV/I_Dark ratio per unit area value of 8.73 × 10⁶ was obtained. The fastest rise time 0.78 s and fastest decay time 0.94 s were obtained by slot-die coated sensors. High photoresponse of ZnO-Ts, the inter-electrode gap size influences formation of ZnO-T microstructure during coating process and morphology influence on photoresponse was explained. We demonstrate that even with the same optimized ZnO-T nanostructures photoresponse can be improved by 2 orders of magnitude. Our work shows the importance of coating morphology and inter-electrode gap optimization.

Photobiomodulation (otherwise known as low level light therapy) is an emerging approach for treating many diseases and conditions such as pain, inflammation, wound healing, brain disorders, hair regrowth etc. The light used in this therapy generally lies in the red and near-infrared spectral regions. Despite many positive studies for treating different conditions, this therapy still faces some skepticism, which has prevented its widespread adoption in clinics. The main reasons behind this skepticism are the lack of comprehensive information about the molecular, cellular, and tissular mechanisms of action, which underpin the positive effects of photobiomodulation. Moreover, there is also another therapeutic application using longer wavelength infrared radiation, involving either infrared saunas or heat lamps which are powered by electricity, as well as infrared emitting textiles and garments which are solely powered by the wearer's own body heat. In recent years, much knowledge has been gained about the mechanism of action underlying these treatments, which will be summarized in this review. There are three broad classes of primary chromophores, which have so far been identified. One is mitochondrial cytochromes (including cytochrome c oxidase), another is opsins and light or heat-sensitive calcium ion channels, and a third is nanostructured water clusters. Light sensitive ion channels are activated by the absorption of light by the chromophore proteins, opsin-3 and opsin-4, while mitochondrial chromophores are activated by red or near-infra red (NIR) light up to about 850 nm. However NIR light at 980 nm or longer wavelengths can activate transient receptor potential (TRP) ion channels, probably after being absorbed by nanostructured water clusters. Heat-activated TRP channels undergo a conformational change triggered by only small temperature changes. Here we will discuss the role of opsins and light or heat activated TRP channels in the mechanism of photobiomodulation and infrared therapy.

The retina of vertebrates is responsible for detecting and capturing ambient light for image and non-image forming (NIF) functions through diverse projections to the brain which regulate visual processing, pupillary light responses, photic synchronization of circadian rhythms and suppression of pineal melatonin, among others. For this, vertebrates have retained through evolution at least two sets of photoreceptors specialized primarily in such visual and NIF tasks: visual photoreceptors cones and rods responsible for day/night vision, and intrinsically photosensitive retinal ganglion cells (ipRGC) together with horizontal cells in some vertebrates, expressing melanopsin (Opn4). Interestingly, Opn4 as well as encephalopsin (Opn3) and neuropsin (Opn5), responding to blue and UV light, respectively, are expressed in the inner retina and command light detection in the blue range of the visible spectra; they are responsible for a number of NIF functions still lacking characterization. Though most retinal photoreceptors are derived from ciliary or neuronal progenitor cells, in recent years Müller glial cells (MCs), the most abundant retinal glial cell type, have been shown to express different blue opsins (Opn3 and Opn5) and the photoisomerase retinal G protein-coupled receptor (RGR), and to respond directly to light. MCs display different essential functions to maintain the homeostasis and cell survival of the whole retina, contributing to glutamate metabolism and chromophore recycling. The novel photoreceptive capacity of MCs, mainly in the blue region, offers several highly intriguing possibilities that increase the complexity levels for light detection in the retina and its light-activated circuits, calling for further investigation. The goal of the present review is to discuss the state of the art of research on the principal macroglial cells in the retina, focusing mainly on the novel photic responses driven by MCs, the biochemical mechanisms triggered after light stimulation and their putative functions and implications.

An increasing number of articles have been published in recent years on the role of the endocannabinoid system (ECS) in different cellular processes. Here we review and discuss findings on the ECS in visual processing and present the structure of the retina. We focus on the photoreceptor cell and the events that occur in the phototransduction process, considering the conformational light-induced changes in rhodopsin and in particular its chromophore (11-cis retinal). Advances in the distribution and function of the endocannabinoid system in the retina with special reference to its function in the physiological light process are also addressed, as is the relationship between rhodopsin, retinal pathologies and the ECS.

Glioblastomas (GBM) are considered one of the most aggressive tumors of the central nervous system. The standard treatment for GBM-diagnosed patients implies surgery, followed by radio and chemotherapy, with a survival of 12 to 15 months after treatment. Photodynamic Therapy (PDT) is an alternative approach to treating several diseases, including tumors. The study of PDT to treat GBM has been gaining attention over the last few years. In this work, we reviewed the cellular and molecular features and current treatment modalities for GBM as well as the most used photosensitizers for GBM-PDT reported in the last five years, such as porphyrins, chlorins, and phthalocyanines, and also their precursors, as in the case of aminolaevulinic acid. Moreover, an analysis of cellular targets, mechanisms mediating the response and resistance to PDT, and clinical application of this strategy for GBM treatment have been discussed.

Chlorophyll (Chl)-deficient plants can potentially increase global surface albedo of mono-cropping systems, and simultaneously maintain a similar photosynthetic efficiency by increasing light canopy penetration and thus lowering investment in pigments. However, some previous studies have shown that pale mutants might reduce productivity in field conditions. Such lower yields were suspected to be due to loss of photosynthetic efficiency at leaf level during light fluctuations as a consequence of reduced capacity and slower relaxation of non-photochemical quenching (NPQ) of Chl fluorescence. In this paper, we tested this hypothesis by comparing, CO₂ assimilation (A), photosystem II (PSII) efficiency (Φ_PSII), photochemical quenching and NPQ, electron transport rate (ETR) and fluorescence yield (F_yield) in a green soybean (Glycine max L.) cultivar (Eiko) and in a Chl-deficient (MinnGold) mutant under dynamically fluctuating light conditions. MinnGold had significantly slower induction of ETR and lower A and ETR than Eiko, but there was little difference in Φ_PSII between the two genotypes, suggesting that the lower photosynthesis of MinnGold was mainly due to lower light energy absorption by a Chl-deficient leaf. The NPQ capacity was also smaller in MinnGold than in Eiko. As for the kinetics of the rapidly inducible component of NPQ, MinnGold showed slower induction, not relaxation, than Eiko. The combination of the effect of Chl-deficiency on lower photosynthesis, NPQ capacity and slower NPQ induction may explain the lower biomass accumulation of MinnGold in the field. Our physiological observations, combined with fluorescence kinetics, can serve as a basis to parameterize Chl content in modelling radiative transfer and photosynthesis for upscaling measures of plant and ecosystem productivity by a big leaf model.

The increase in cancer in recent years suggests an inadvertent exposure to agents that cause genetic damage. The polarized polychromatic noncoherent light Bioptron® lamp is used to accelerate healing, among other therapeutic applications and its potential carcinogenic effects as a mitogenic agent have not been explored. The objective was to evaluate the genotoxicity of the Bioptron light therapy by means of the micronucleus assay in mouse erythrocytes. Male SKH1 hairless mice were randomly divided into six groups (5 mice/group); Group 1: negative control received ambient light; Group 2: positive control was exposed to ultraviolet light lamp A (UV-A) for 80 min; Experimental Groups 3–6 were exposed to the Bioptron lamp light for 10, 20, 40 and 80 min, respectively. Exposures in all groups were once a day for 4 days and blood smears were performed daily for 5 days and subsequently read with a microscope equipped with epifluorescence. The values of micronucleated erythrocytes (MNE), micronucleated polychromatic erythrocytes (MNPCE) and the proportion of polychromatic erythrocytes (PCE) were determined. The study group that received the UV-A light was the only one that increased MNE and MNPCE values, while in the groups exposed to the Bioptron lamp and the negative control did not show increases in any of the sampling days. In conclusion, under the conditions presented here, our results suggest that the light of the Bioptron lamp does not cause damage to the genetic material of SKH1 mice, by means of the micronucleus test in peripheral blood.

This work reports the mid-IR spectroscopy and reaction kinetics of 2-methyl-1,3-dioxolane (2M13DO). We carried out spectroscopic measurements to deduce temperature-dependent absorption cross-sections of 2M13DO over a broad wavelength range of 8.4–10.5 μm (950–1190 cm⁻¹). For these measurements, we employed a rapidly tuning MIRcat-QT™ laser that can be operated either at a fixed wavelength or scanned mode over wide wavelength regions. By operating the laser at a fixed wavelength, we monitored the decay of 2M13DO behind reflected shock waves over T₅ = 1050–1400 K and P₅ = 0.7 and 2.6 bar. Our measured concentration time-histories of 2M13DO allowed us to directly extract the overall rate coefficients for the unimolecular decomposition of 2M13DO using the first-order rate law. We did not observe any pressure dependence in the measured rate coefficients, indicating that the reaction is close to the high-pressure limit. By employing the W1U composite method, we explored the important pyrolysis reaction pathways of 2M13DO in the reactive potential energy surface. Three important reaction channels, namely, 2M13DO → CH₂CHOCH₂CH₂OH (IM1), 2M13DO → 2CH₃CHO (P3), 2M13DO → CH₃ + 1,3-dioxolan-2-yl (P4) were identified. Below 700 K, IM1 forming channel is dominant, whereas CH₃CHO formation is dominant under our experimental conditions. Above 1500 K, the radical forming channel (CH₃+P4) takes over other channels. At higher temperatures, the contribution of the radical forming channel continually increases, accounting for ∼ 99% at 2000 K. We used the stochastic RRKM-ME model to predict the pressure and temperature dependence of the rate coefficients, k(T, P), and time-resolved species profiles. Our theory showed excellent agreement with the measured rate coefficients. These are the first direct determination of the rate coefficients of the unimolecular decomposition of 2M13DO.

By the application of simultaneous target analysis of multiple femtosecond transient absorption data sets we have identified two loss channels within multi-chromophoric light harvesting arrays. Perylene bisimide-calix[4]arene arrays composed of up to three different types of perylene bisimide (PBI) chromophores, orange (o), red (r), and green (g) PBIs (named after their colors as solids), have previously been studied by transient absorption spectroscopy (Hippius et al., J. Phys. Chem C 112:2476, 2008) and here we present a simultaneous target analysis of those data matrices. A covalent system containing the red chromophore (r) and calix[4]arene (c), the rc system, shows extensive spectral evolution that can be described with four excited states (r₁*→r₂*→r₃*→r₄*→ground state). In the Perylene Orange calix[4]arene system (oc), a radical pair (ocRP) can be formed by photoinduced electron transfer (Hippius et al., J. Phys. Chem C 111:13988, 2007). In a simultaneous target analysis of the multichromophoric systems ocr, rcocr and ocrco the properties of rc and oc are integrated, and excitation energy transfer (EET) from o* to r* occurs. In addition, we demonstrate that the final Species Associated Difference Spectrum (SADS) also contains o bleach features that indicate an excitonic interaction, for ocr, rcocr and ocrco. In a simultaneous target analysis of rcg and gcrcg the properties of rc are integrated, and next to EET to g* we can resolve the formation of a new rcgRP that is formed from r₁* or r₂*, and represents a loss of 7 and 12%, respectively. In a simultaneous target analysis of ocrcg the properties of ocr and rcg are integrated, arriving at a consistent picture with an energy transfer quantum yield of formation of the excited state of the green PBI (g*) of 80%.