Photochemistry and Photobiology最新文献

Ultraviolet-C (UV-C) at a wavelength of 254 nm is used for disinfection but cannot be used in dwelling space because it is harmful to the human body, while 222-nm Far UV-C shows germicidal effect and poses little hazardous effect to human. Formation of cyclobutane pyrimidine dimers (CPD) of DNA is a main mechanism of UV-C germicidal effect. CPD formed by irradiation with 254-nm UV-C is repaired and bacterial proliferation is recovered by photoreactivation. In this study, we investigated photoreactivation of Staphylococcus aureus irradiated with 222-nm Far UV-C. The proliferative effect of 222-nm Far UV-C irradiated S. aureus by photoreactivation was inferior to that of irradiated with 254-nm UV-C. The 254-nm UV-C wavelength and 222-nm Far UV-C induced CPD in S. aureus cells, and the same level of CPD was repaired in cells irradiated with either UV-C after photoreactivation. It has been reported that UV-C induces generation of reactive oxygen species (ROS) in bacteria and that ROS oxidize and inactivate a variety of biomolecules in bacteria. This study showed that more ROS-producing S. aureus were observed after irradiation with 222-nm Far UV-C compared with 254-nm UV-C. These results indicate that ROS may be involved in lower recovery of 222-nm Far UV-C irradiated S. aureus by photoreactivation.

Onychomycosis, predominantly induced by Trichophyton rubrum, is a pervasive nail disorder within dermatology known for its high relapse rates and suboptimal patient adherence to treatment regimens. While photomedicine has emerged as a promising therapeutic modality, efficiency reductions are common due to deck obstruction in conventional light therapy. The spectral flexibility of LEDs offers a compelling solution, allowing for deeper deck penetration while maintaining efficacy. We have developed an advanced LED system with optimized optical parameters and have elucidated the antimicrobial mechanisms underlying this technology. Our research shows that an optimal wavelength of 405 nm, an energy density of 396 J/cm², and an average light intensity of 140 mW/cm² demonstrate superior efficacy in treating onychomycosis. The antifungal mechanism of our pulsed LED system involves the induction of reactive oxygen species (ROS) within fungal mycelia, ultimately resulting in membrane damage. These insights highlight the potential of LED lighting systems as a novel antimicrobial strategy, offering a promising avenue for the treatment of onychomycosis.

This study investigates the effects of photobiomodulation (PBM) with a 660-nm laser on nerve regeneration and muscle morphometry following median nerve axonotmesis in rats. Sixteen Wistar rats were divided into a control group and laser-treated group, with the latter receiving 10 applications of PBM (660 nm; 20 mW; 10 J/cm²; 0.4 J; and 20 s) over 2 weeks. Functional analysis was performed using the grasping test, which measures the grip strength of the forelimb digits to evaluate motor function of the median nerve. Morphometric analyses were conducted on the median nerve, flexor digitorum (FD) muscle, and flexor carpi radialis (FCR) muscle. PBM led to functional improvement, with significant differences observed on the 21st day post-injury. However, no significant differences between groups were found in nerve morphometry. Morphometric analysis of the FD muscle revealed significant improvements in the PBM group, but with no significant differences regarding the FCR muscle. These findings suggest that 660-nm laser with the parameters used produced functional improvement as well as significant improvements in the morphometry of the FD muscle, but did not have significant effects on the morphometry of the FCR muscle or nerve regeneration.

We aimed to compare the anticandidal effect among different preirradiation times, measure singlet oxygen levels, and investigate the correlation between candidal reduction and singlet oxygen formation in erythrosine + KI photodynamic therapy. Candida albicans (ATCC10231) biofilms were treated with 100/200 μM erythrosine + 100 mM KI for 1, 3, or 5 min before light-emitting diode (520 ± 10 nm, 250 mW/cm², 20 J/cm²) irradiation. Phosphate-buffered saline, and nystatin were negative and positive controls, respectively. Candidal cells were quantified using a drop plate assay. Singlet oxygen was measured using a 9,10-dimethylanthacene probe at 375/436 nm emission/excitation wavelengths. Median candidal counts and singlet oxygen formation were compared using Kruskal-Wallis with Dunn test. A p-value <0.05 was considered significant. Spearman's correlation was used to correlate candidal reduction and singlet oxygen formation. All preirradiation times for 200 μM erythrosine + 100 mM KI decreased candidal cells by 7.59 (IQR = 0.33) log₁₀CFU/mL. At a 1-min preirradiation, this group significantly generated higher singlet oxygen than the positive control (p < 0.001). Singlet oxygen levels correlated mildly with candidal reduction in the lower erythrosine group but not the higher group, likely due to singlet oxygen saturation. A 1-min preirradiation with 200 μM erythrosine + 100 mM KI generates singlet oxygen to inhibit C. albicans biofilms and shows potential for clinical oral candidiasis treatment.

This study investigated the synergistic effects of resveratrol and antimicrobial photodynamic therapy (aPDT) on peri-implant bone repair in a type 2 diabetes model. Forty-eight rats were allocated into four groups: normoglycemic, normoglycemic + resveratrol, type 2 diabetes (T2D), and T2D + resveratrol. Diabetes was induced using a cafeteria diet and streptozotocin (35 mg/kg). Resveratrol (100 mg/kg) was administered systemically beginning 7 days later. After 14 days, maxillary molars were extracted, and surgical drilling was performed. Half of the animals in each group received aPDT (methylene blue and 660 nm diode laser) before immediate implant placement. Animals were euthanized 28 days post-surgery for biomechanical, RT-PCR, and confocal microscopy analyses. Resveratrol improved glycemic control and body weight. In T2D animals, aPDT significantly enhanced implant removal torque. Gene expression analyses revealed downregulation of bone resorption markers and upregulation of bone mineralization genes in T2D and T2D + resveratrol groups treated with aPDT. Confocal microscopy demonstrated increased mineral apposition rates in animals treated with resveratrol and/or aPDT. These findings suggest that the combination of systemic resveratrol and local aPDT enhances peri-implant bone healing under diabetic conditions, highlighting a potential therapeutic approach to improve implant osseointegration in compromised metabolic states.

Exposure to UVR is well understood to accelerate symptoms of photoaging such as wrinkling and loss of skin elasticity. Sunscreen formulations containing titanium dioxide (TiO₂) and zinc oxide (ZnO) UV filters can therefore be used as an effective photoprotective measure to prevent the induction of signaling pathways in skin that contribute to photoaging. The aim of this study is to provide a broad investigation on the photoprotective impact of TiO₂, ZnO, and inorganic-only (ZnO + TiO₂) sunscreen formulations in human dermal fibroblasts at a gene and protein level. The study focused on genes involved in UV-only and complete solar light-induced MMP production, prostanoid biosynthesis for inflammation, and cell cycle arrest, as previously identified through RNA-seq analysis. Three inorganic formulations were prepared at commercially applicable active levels and varying particle sizes: (1) F(TiO₂ ^179nm), (2) F(ZnO^57nm), and (3) an inorganic-only (ZnO + TiO₂) formulation F(ZnO^57nm/TiO₂ ^47nm). The three formulations significantly alleviated the irradiation-induced expression of MMP1, MMP3, PTGS1, PTGES, MDM2, CDKN1A, and CCNE2, with the latter most alleviated by up to 77% (p ≤ 0.05). The inorganic-only (ZnO + TiO₂) formulation, containing both inorganic UV filters, exhibited the greatest mean or maximum alleviation in 75% of the genes investigated. Protein analyses of MMP1, PTGES, and p21, by immunocytochemistry and Western blot, also showed positive translation of alleviation at a protein level. The study provides further academic and commercial insights on the photoprotective impact of inorganic particles in sunscreens, based on relevant signaling pathways, genes, and proteins that are induced by UV to accelerate photoaging.

Exposure to the ultraviolet (UV) spectrum of sunlight poses a threat to terrestrial species. Nearly all species possess the nucleotide excision repair (NER) machinery, which can repair the helix-distorting DNA lesions induced by UV light. However, many species also have photolyase enzymes, which use near-UV and visible wavelengths of sunlight to directly reverse major classes of UV photoproducts. In eukaryotic cells, both of these repair pathways must efficiently locate and repair UV photoproducts present in chromatin. While genome-wide damage mapping methods have been used to extensively characterize how chromatin and ongoing transcription impact NER, much less is known about how photolyase enzymes navigate these obstacles to repair UV damage. Here, we highlight a recent article from our laboratory that used genome-wide sequencing methods to characterize how yeast photolyase repairs UV damage, both in NER-proficient and -deficient cells, and prevents UV-induced mutations.

The SKH-1 mouse model is commonly used to assess the effects of ultraviolet light exposure on skin using visual and biological endpoints. Although skin bi-fold thickness is a well-established quantitative measure of edema, evidence characterizing its use to evaluate skin responses in the UVC range remains limited. This study evaluated skin bi-fold thickness measurements made using a digital caliper. Hairless SKH-1 mice were exposed using the narrow bandwidth output from a monochromator with wavelengths from 200 to 270 nm. Post-exposure thickness measurements were normalized against pre-exposure thickness measurements to determine the fold change. These findings were compared with qualitative visual assessments of changes to the skin. The results indicate that quantitative measures of increases in skin thickness are correlated with subjective visual scoring measures. The observed magnitude of the bi-fold change following UVC exposures was limited in this study because exposures were at doses close to the threshold dose for causing a visually observed change to the skin. The results support using skin bi-fold measurements for quantifying skin responses to ultraviolet light exposure.

Phototherapy approaches include photodynamic therapy (PDT), which utilizes chemically stable photocatalysts to sensitize the conversion of endogenous molecules such as oxygen (O₂) to form transient reactive species such as ¹O₂, and photopharmacology, a complementary approach that relies on molecules that undergo self-modifying photochemistry, such as bond cleavage reactions or isomerization, for the creation of biologically active products. While Ru(II) polypyridyl systems have demonstrated utility for both approaches, related organometallic systems are relatively less explored. Here, the photochemistry and photobiological responses were compared for five Ru(II) arene compounds containing photolabile monodentate azine ligands and the π-expansive bidentate ligands dipyrido[3,2-a:2',3'-c]phenazine (dppz), 4,5,9,16-tetraaza-dibenzo[a,c]naphthacene (dppn), and α-terthienyl-appended imidazo[4,5-f][1,10]phenanthroline (IP-3T). The compounds demonstrated significant light-mediated photocytotoxicity in lung cancer and melanoma cell lines, with up to 6000-fold increases in cytotoxicity upon irradiation. The arene systems were capable of partitioning between different excited state relaxation pathways, both releasing the monodentate ligand and generating ¹O₂, but with notably low yields that did not correlate with the photocytotoxicity of the systems. The organometallic compounds exhibit less mixing of the metal-associated and ligand-centered excited states than analogous polypyridyl coordination compounds, providing a structurally, photochemically, and photobiologically distinct class of compounds that can support both metal- and ligand-centered reactivity.