Journal of Photochemistry and Photobiology最新文献

A series of 3,6-diamino-9-naphthylcarbazole derivatives were synthesized and characterized experimentally and computationally. As the lowest unoccupied molecular orbital of the naphthyl group has lower energy than that of the phenyl group, a charge transfer from carbazole to naphthyl in the excited states occurred causing solvatofluorochromism and solvent-dependency in fluorescence quantum yields. A molecule having two carbazole substituents sandwiching the central naphthyl ring had absorption reaching 470 nm and a high reducing capability in the excited state. This molecule could successfully photosensitize the hydrodehalogenation of haloarenes under visible light irradiation.

Retinal phototoxicity is the main mechanism by which light induces damage to the retina, the sensitive part of the eye. The impact of light on the different retinal layers varies depending on several factors including the wavelength of the incident light, its energy, and the exposure time. We propose an overview of the factors modulating the amount of light that reaches the retina, the type of damage, and the different cell death mechanisms triggered by phototoxicity to mediate cell demise in the retina. We also provide an analysis of the phototoxicity mechanisms induced by light depending on the lighting settings. Special interest is given to the influence of the emission spectrum on the induction of specific cell death pathways. Moreover, the existing literature on phototoxicity is reviewed by taking into consideration the used doses of light.

Titanium dioxide nanoparticles are widely used in cosmetics, especially in sunscreens due to their capacity to absorb UV harmful wavelengths. However, their biocompatibility remains controversial. In this work, the effect of titanium dioxide nanoparticles, particularly Degussa P25 (P25TiO₂NPs) under solar-simulated radiation was studied in vitro and in vivo. Cell viability and tissue integrity were affected after exposure to P25TiO₂NPs and light for 6 h, showing signs of significant oxidative stress markers and reduced tissue integrity observed by TEM. In order to avoid these undesired effects, a novel biocompatible alternative was presented based on titanium dioxide nanoparticle functionalization with vitamin B2 through a rapid sol-gel method. None of the phototoxicity effects were observed with these functionalized nanoparticles.

Detecting different wavelengths and intensities of environmental light is crucial for the survival of many animals. In response, a multiplicity of opsins (a special group of photosensitive G protein-coupled receptors), when combined with a retinal chromophore, is able to directly detect light and initiate different downstream phototransduction signaling cascades. Although avian studies from the 1930s suggested the presence of deep brain photoreceptors that could respond to seasonal changes in the light/dark cycle, it was only a few decades ago that photopigments other than those found in the visual system (i.e. rods and cones) were identified as functional photoreceptors. It is now established that several classes of non-visual photoreceptors and the photopigments they express, in lower vertebrates to higher mammals alike, can regulate a plethora of mechanisms that function outside of vision. These include the synchronization of light/dark cycles with biological/cellular rhythms of the body (i.e. photoentrainment); melanogenesis in dermal tissues; thermoregulation in adipose tissue; embryonic eye development; smooth muscle relaxation; and the development of certain cancers. These and other mechanisms have been shown, in part at least, to be controlled by the expression of three important non-visual opsin genes, namely OPN3, OPN4 and OPN5, although other vertebrate opsin classes exist, many with unknown or unclear functional roles assigned to them presently. Specifically, these three opsins have been shown to be expressed during early embryogenesis and throughout adulthood, which will be discussed here. Moreover, this review highlights recent studies that focus on several key non-image-forming functional roles of OPN3, OPN4 and OPN5, and in particular those that impact photoreception in developing structures and pathways, as well as in adulthood.

In comparison with single-phase materials, heterostructures have been known for superior water splitting applications. In this study, Cu₂O and NiFe₂O₄ are chosen to fabricate thin film heterostructures. Cu₂O is electrodeposited at 60 °C for 5 min on ITO-coated glass substrates using three-electrode system. After deposition, the phase formation is confirmed using powder x-ray diffraction studies. The NiFe₂O₄ (NFO) thin films are deposited using RF sputtering method at room temperature for 2 h on Cu₂O/ITO substrates to obtain NFO/Cu₂O/ITO Type-II heterostructure. The scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) cross-sectional images show that the thickness of NFO layer is 120 nm and Cu₂O layer is 1.5 µm. The photocurrent density of Cu₂O on ITO is 0.08 ± 0.002 mA/cm², and it increased to 0.12 ± 0.002 mA/cm² after adding NFO layer on Cu₂O film due to Type-II heterojunction formation.

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.