Journal of Photochemistry and Photobiology最新文献

Photobiomodulation (PBM) is a noninvasive photonic-based therapy, capable of dealing with immune-inflammatory, neurological, and musculoskeletal disorders, as well as healing oral and chronic skin wounds. During PBM light is applied at a specific wavelength, either in the visible or near-infrared (NIR) ranges. Photophysical and photochemical processes might stimulate or inhibit various biological processes, depending on the target tissue, the wavelength of light, irradiance, fluence, repetition rate (pulse frequency), spot size, optical data of the tissue to be irradiated and treatment regimen. There are several randomized clinical studies demonstrating the PBM benefits as main or adjuvant therapies. Of importance to this review, there is a large piece of evidence in the management of skin or venous ulcers, and diabetic foot. In this review, the PBM´s efficacy as adjuvant therapy to deal with chronic human ulcers were discussed concerning the photophysical parameters and clinical aspects. Beside, we overview the state-of-the-art regarding the cellular and molecular modulatory mechanisms photoactivated by red and NIR light.

Electron donor and acceptor undergo association in solution to form a weak molecular complex, namely a charge transfer complex. The formation of the complex is apparent by its new low-energy absorption band. Upon photoexcitation of this charge transfer band, an intracomplex electron transfer is facilitated to form a contact ion radical pair. The theoretical basis for the complex formation and the subsequent photoinduced electron transfer process has been well established already half a century ago. Nevertheless, the charge transfer complex photochemistry is now in a renaissance, due to its synthetic utility of its radical ion pair. By intentionally sidestepped unproductive back electron transfer process, a desired product is effectively obtained with or without external reagent and/or catalyst. In addition, the photoexcitation of the complex does not require any additional photocatalyst and often conceivable with the visible light. Accordingly, various donor/acceptor pairs and synthetic applications have been emerged as novel photoreaction systems in the last two decades. Some have also addressed the stereoselective transformations. This mini review highlights the recent progress of the asymmetric photoreaction, in particular in synthetic applications, based on the photoexcitation of the charge transfer complex, in comparison with photoredox catalysis.

Prior to the coronavirus disease-19 (COVID-19) pandemic, the germicidal effects of visible light (λ = 400 – 700 nm) were well known. This review provides an overview of new findings that suggest there are direct inactivating effects of visible light – particularly blue wavelengths (λ = 400 – 500 nm) – on exposed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virions, and inhibitory effects on viral replication in infected cells. These findings complement emerging evidence that there may be clinical benefits of orally administered blue light for limiting the severity of COVID-19. Possible mechanisms of action of blue light (e.g., regulation of reactive oxygen species) and important mediators (e.g., melatonin) are discussed.

Our laboratory has been studying the strong enhancement in the fluorescence quantum yield and an excited lifetime of the organic dye molecules on the clay nanosheets and refer to as “Surface-Fixation Induced Emission”. In this study, Safranine-O which is a mono-cationic phenazine-based dye molecule, was used as the organic dye. It has fluorescence enhancement properties on the clay surface due to the suppression of the non-radiative deactivation rate constant (k_nr) on the clay nanosheets. While Safranine-O in water in the absence of clay nanosheets exhibited the values as 0.068 and 1.09 × 10⁻⁹ s for ϕ_f and τ, those on the clay surface are 0.121 and 1.96 × 10⁻⁹ s. k_nr values in water and on the clay were calculated to be 8.6 × 10⁸ s ^− 1 and 4.5 × 10⁸ s ^− 1, respectively. These results can be explained well by the structure fixing and structure resembling effect. This study helps to explore the possibility of utilizing mono-cationic dye molecules for the realization of desired photo-functional materials and photochemical reactions.

The pupil reacts to the amount of light reaching the eye. It reduces its size when the light is high and dilates at low light levels to allow the entrance of more photons. This behavior is called pupil light reflex (PLR). Recent investigations in humans were conducted to understand how the photoreceptor signals are combined to drive the pupil light reflex. This review is about the physiological processes that govern the pupil in humans. In particular, how cone-opsins, rhodopsin, and melanopsin photoreception contribute to governing the PLR. We also summarize investigations on the assessment of the PLR in clinical settings.

Opsins are light-sensitive proteins that are found across the animal kingdom. In mammals, opsins are classically associated with image-forming processes, a function exerted by cone and rod opsins. In early 2000, melanopsin was identified in the human retina as an important regulator of non-image forming events such as melatonin suppression, pupillary constriction, and circadian rhythm adjustment. The presence of different opsins and the biological processes that these proteins regulate in the skin are increasingly being described. Currently, opsins are considered light as well as thermosensors in the skin. However, additional regulatory functions, in a light and thermo-independent fashion, mostly likely via protein-protein interaction have set a new field of study. The goal of this review is to critically revise the literature on the role of opsins in skin physiology as well as in melanoma cancer.

Phlorotannins are believed to provide UV protection in brown algae. In Fucus species, phlorotannin-rich vesicles (“physodes”) form an “epidermal physode layer”, which might represent the anatomical structure responsible for UV protection. However, this layer has been neglected so far; instead, phlorotannin contents of entire thalli were studied in UV exposure experiments.

We employed fluorometric methods to investigate in which wavelength region and to which degree the epidermal physode layer of two Fucus species reduces the transmittance of UV radiation. For comparison, we also studied Saccharina latissima, a brown algal species without epidermal physode layer.

We could show that the epidermal physode layer absorbs throughout the entire UV wavelength range and reduces the epidermal UV-B transmittance into the thallus strongly (15% transmitted in F. vesiculosus vs. 80–100% in S. latissima). UV-B transmittances varied with growth depth and the variations correlated with photosystem II (PSII) stress responses upon artificial UV-B illumination. We found that the UV-B protection is more than sufficient for natural UV-B levels and of rather constitutive nature.

In conclusion, the epidermal physode layer appears to be the anatomical feature exerting UV protection by phlorotannins in Fucus species and might thus be a core adaptation that enables Fucales the colonization of the intertidal habitat.

Studying the uptake mechanism of photosensitizers is an important step in developing an ideal photosensitizer for use in photodynamic therapy (PDT). Understanding the uptake mechanism can help design novel photosensitizers that are selectively accumulated in the target tissue, with improved pharmacokinetics, and are dosed optimally to maximize the efficacy of the treatment. In our previous studies we synthesized and characterized the use of chitosan nanoparticles functionalized with rose bengal (CSRBnp) as a photosensitizer against dental biofilm. The aim of this study is to analyze the internalization mechanism and cellular proinflammatory activities of CSRBnps on fibroblasts. Fibroblasts (NIH 3T3) were incubated with chlorpromazine (5 µg/ml), nystatin (5 µg/ml), wortmannin (100 ng/ml) and at 4 °C for 30 min followed by CSRBnp (0.3 mg/ml). Cell viability (MTS assay), intracellular adenosine triphosphate content (Luminescence assay), cytokine expression (TNF-α) using ELISA and nitric oxide (NO) production by Griess reaction system were conducted at different time intervals (30 min, 1, 4, and 12 h). The internalization of CSRBnps was analyzed using live cell imaging confocal microscope with excitation wavelengths of 405 and 568 to detect nuclei (Hoechst 33,342) and CSRBnps respectively. CSRBnps and inhibitors at the applied concentrations were not cytotoxic. ATP content in chlorpromazine and without inhibitors groups were significantly lower than the control group at 12 h. All inhibitors showed significantly lower CSRBnps uptake compared to the control group at 30 min, 1 h, and 4 h time. Wortmannin resulted in the most significant inhibition of CSRBnps uptake as compared to chlorpromazine and nystatin (P < 0.05). TNF-α expression and NO production were not significant during the entire CSRBnps uptake. The results showed macropinocytosis was a dominant CSRBnps uptake mechanism by fibroblasts in the early stages and non-specific uptake pathways were activated after prolonged incubation time. CSRBnps uptake by fibroblasts was energy dependent and did not cause any proinflammatory response.

The UV Index (UVI), standardized by the World Health Organization (WHO) in 2002, is an internationally accepted reference for disseminating information on solar UV radiation levels with the purpose of preventing the harmful effects on human health by sun overexposure. The UVI is the erythemal irradiance expressed in a dimensionless unit, with numerical values adapted to a risk scale that considers the “Extreme” level from a UVI value equal to 11 upwards. This scale is linked to a color palette by health risk ranges, and to a graded color palette by units of UVI for more details. Both the numerical scale and its associated risk levels were universally adopted by the scientific community and by global information systems to the population. However, inconsistencies and limitations persist between both UVI color palettes, making their interpretation and application difficult. In the present work all these aspects are addressed, proposing a revised color palette for unit UVI values that resolves each of them. Based on the WHO risk-ranges UVI color palette, the new color palette for unit UVI values gives coherence to both color charts, allowing reliable identification of the risk level bands and of each unit UVI level within them, and solves the need to distinguish between units for numerical values of UVI higher than 11 that are registered daily in many regions of the world.

2-Aza-9-fluorenone derivatives were synthesized and their optical properties were investigated. The UV–visible absrption spectra revealed λ_max values in the range of 350–380 nm, with a shift to the longer wavelength when an electron-donating group was substituted on the aryl group at the 3-position adjacent to the nitrogen in the azafluorenone. N-Methyl-2-azafluorenone was synthesized by methylating the nitrogen of azafluorenone. The N-methyl derivative was found to have a maximum absorption at 426 nm from UV-Vis spectral measurements, and electrochemical measurements revealed that it has a lower first reduction potential and higher electron-accepting ability than azafluorenone. In addition, the application of azafluorenone as a photocatalyst was investigated, focusing on its structural and electronic features. Oxidation of toluene with azafluorenone as a photocatalyst yielded benzoic acid in high yield. Electron-transfer dynamics analysis using nanosecond time-resolved laser flash photolysis suggests that azafluorenone and N-methylazafluorenone act as hydrogen transfer and electron transfer catalysts, respectively.