Journal of Photochemistry and Photobiology最新文献

Since recent global pandemic started, there has been a high demand for establishing an inexpensive but effective method to interfere with the spread of infectious diseases. Here, we have tested several combinations of violet light (V, 405 nm) with infra-red (IR, 850 nm) to identify an optimal light for suppressing pathogens. Our results demonstrate that both violet only (4 V) and 3V-1IR (3:1 ratio in combination of violet and infra-red) effectively suppressed all the bacterial growth tested, including Gram-negative and -positive multi-drug resistant (MDR) strains. Both 4 V and 3V-1IR equally terminated standard strains of Escherichia coli and Staphylococcus aureus, as well as MDR-strains (E. coli, Salmonella enterica and S. aureus from ATCC) effectively. In mechanism, the violet light enhanced the level of reactive oxygen species (ROS) for bactericidal effects, however, we have observed a slightly higher potency from 3V-1IR at a shorter distance, probably due to mild heat-derived dehydration by IR. Therefore, we suggest to expose 3V-1IR for short distance applications (≤1 meter) and both 4 V and 3V-1IR for longer distance (≥1 m). Notably, our results strongly suggest that the exposure of safe violet light or with infra-red can be an effective method to suppress the potential spread of bacteria-derived infectious diseases.

Visible light-driven benzoyl azides formation catalyzed by a rhodium ion modified TiO₂ (Rh³⁺/TiO₂) is reported. The Rh³⁺/TiO₂ was prepared as a visible light responsive photocatalyst by a simple procedure from TiO₂ and RhCl₃･3H₂O. The Rh³⁺/TiO₂ exhibited a broaden visible light absorption from 400 nm to 600 nm. Benzoyl azide formation from a benzotrichloride and a trimethylsilyl azide (TMS-N₃) was performed catalyzed by the Rh³⁺/TiO₂ under visible light irradiation (λ ≥ 420 nm) in air at room temperature. In this reaction, the benzotrichloride was effectively reduced by the single electron transfer (SET) from the Rh³⁺/TiO₂, and the benzoyl azide was produced in 71% yield via the reaction between the benzoyl chloride and TMS-N₃. In addition, several benzotrichloride derivatives were applied to this reaction and the corresponding benzoyl azide derivatives were formed in up to 71% yield. A kinetic analysis was also performed on these reactions, and it was suggested that the SET is the rate determining step in this reaction.

The study of photochemical reactions is of great importance in many fields including the pharmaceutical, food, and paint industry. Most of these photochemical processes are being studied to better understand how to apply them for a specific purpose or how unwanted effects can be prevented. Advances are still being made in photoreactor design, where in-situ detection of the involved reagents and products is an important development. Liquid-core waveguides (LCWs) allow simultaneous illumination and optical assessment of liquid samples and, therefore, constitute one way of combining photoreactor design with on-line or in-situ analytical detection methods. LCWs possess several interesting characteristics, such as low light loss, increased optical path length, and possibilities for coupling with spectroscopic techniques. The current review discusses the state-of-the-art of LCWs applied as photoreactors, for analytical detection, and their combinations. We discuss the differences between several total internal reflection (TIR)-based LCWs, including polymer and polymer-coated capillaries, and silica aerogels, and interference-based waveguides, including Bragg fibers, holey fibers, Kagomé fibers and anti-resonance reflecting optical waveguides (ARROWs). Assessed characteristics include the (freedom of) design, the degree of light attenuation, the range of transmittable wavelengths, gas permeability, compatibility with analytical techniques, current challenges, and applications.

Rods are the most sensitive cells to light present in the retina, being therefore responsible for dim light vision. Light photons captured by the retina stimulate rhodopsin, promoting phototransduction mechanisms that end up sending the information to the brain. However, overexposure to light and continuous receptor stimulation may promote retinal damage. Thus, artificial light might have harmful effects on the retina, most particularly in rods. Light‐emitting diodes (LEDs) are nowadays the most used devices, and therefore their potential damage to the visual system should be evaluated and considered as a potential environmental factor in retinal degeneration. Particularly in Wistar rats, tonic receptors stimulation under constant light exposure (LL) produces retinal remodeling, inducing classical photoreceptors death and a re-location of non-classical opsins.

This work aims to show the effects of LED devices on rat retinas under intermittent stimulation. Wistar rats were exposed to white LED under 12:12 light/dark cycles for seven days (LD) to finally analyze the number of photoreceptors nuclei, electroretinograms (ERGs) activity, and glial activation. Our findings demonstrate that animals exposed to LED devices, even when they have intermittent periods of rest in darkness, present early retinal injury after seven days, compared with animals maintained in housing conditions (LDR) or darkness (DD). Altogether, these results suggest that extended LD conditions might induce retinal damage as constant light exposure (LL) does.

In this study, we evaluated the photostability of a cocrystal of naproxen (NPX) and nicotinamide (NA) for the development of the photostabilization strategy. NPX photodegradation during ultraviolet-light (UV) irradiation was estimated by high-performance liquid chromatography (HPLC). The photostability of a NPX-NA cocrystal was less than NPX in the solid-state. Furthermore, NPX was photodegraded faster in the presence of NA at a higher concentration when the NPX-NA mixtures were UV-irradiated. The values of residual amounts of NPX in UV-irradiated NPX-NA cocrystal and mixture were 76.60 ± 3.85% and 70.06 ± 4.09%, respectively, which were significantly lower compared with that of UV-irradiated NPX powder (83.57 ± 2.15%). However, in the case that the effect of NA in the suspension of NPX was investigated, NA had no effect on NPX photodegradation. Residual amounts of NPX in UV-irradiated suspensions of NPX and NPX-NA cocrystal were comparable (33.13 ± 6.02% and 30.22 ± 2.09%, respectively). These results suggested that NA might promote NPX photodegradation only in the solid-state on account of that NA molecule could deliver the excitation energy to NPX molecule. This is the first study focused on the photochemical behavior of NPX-NA cocrystal and mixture and suggests that the presence of NA might induce the change of photostability of NPX in the powder form.

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.