Photochemistry and Photobiology最新文献

Germicidal ultraviolet (GUV) air treatment technologies can be effective and safe for reducing airborne disease transmission. Today, GUV systems are designed and evaluated using simulation and measurement tools that require further assessment of their accuracy in estimating fluence rate and irradiance. This article reports results from two experiments where two simulation software (Visual Lighting and Photopia) and two measurement techniques (tetrahedron and cubic approximations) were evaluated against chemical actinometry for quantification of GUV fluence rate in a chamber. Additionally, Visual and Photopia were compared to measurements of planar UV-C irradiance for eye and skin exposure. Results showed that overall mean fluence rates were similar between actinometry and both simulation software for WR GUV systems as well as between actinometry and Photopia for UR GUV systems. The tetrahedron approximation better predicted overall mean fluence rate for WR and UR GUV systems, compared to a cubic approximation which tended to overestimate it. Compared to measurements, simulated eye and skin irradiance varied, with higher variability in simulated eye irradiance. The evaluated simulation software can be used to guide the design of GUV systems but must be supplemented with in situ measurements.

UV radiation (UVR) leads to the formation of potentially lethal and chromosome-destabilizing double-strand breaks (DSBs) in DNA. However, most studies on UVR-induced DSB formation and repair have used cells that are actively progressing throughout the cell cycle. To explore how nonreplicating, quiescent cells deal with UVR-induced DSBs, we used small-molecule inhibitors of various DSB repair pathways and unexpectedly observed a major role for the recombination protein RAD51 in promoting quiescent HaCaT keratinocyte survival. We further observed that both DSB formation and RAD51 function occur independently of nucleotide excision repair, which generates potentially unstable single-stranded DNA gaps. However, RAD51 inhibition also sensitizes quiescent cells to agents that are known to inhibit transcription, thus suggesting a role for transcription in UVR-induced DSB formation. Interestingly, siRNA-mediated knockdown of RAD51 did not sensitize cells to UVR to the same extent as pharmacological inhibition did. In contrast, knockdown of several Rad51 paralogs negatively impacted cell viability after UVR exposure, similar to pharmacological inhibition, suggesting that pharmacological inhibitors of RAD51 may also target one or more RAD51 paralogs. In summary, these findings highlight the important roles of RAD51 and its paralogs in promoting quiescent cell survival in response to UVR.

Head and neck cancer (HNC) affects thousands globally, with high morbidity rates due to standard treatments like surgery and radiation. Photodynamic therapy (PDT) has shown great promise as a less destructive alternative, selectively targeting tumors while preserving healthy tissue. However, assessing treatment response in the days after PDT is challenging due to significant inflammation and the subsequent vascular shutdown of the tumor. We hypothesize that fluorescence paired-agent imaging (PAI) can provide early molecular insights within 24 h of PDT to evaluate treatment efficacy. PAI utilizes two fluorescent agents to correct for perfusion-related changes, allowing for accurate quantification of key signaling proteins. Specifically, we tracked epidermal growth factor receptor (EGFR) response to benzoporphyrin derivative monoacid (BPD)-PDT at 690 nm, with light fluences ranging from 0 to 100 J/cm². Twenty-four hours post-PDT, EGFR concentrations were measured using PAI with ABY-029 and IRDye 680LT as targeted and untargeted agents, respectively. These findings were compared to histopathology (H&E and EGFR IHC). Our histological results demonstrated that EGFR expression increased with low PDT doses (10 and 25 J/cm²) and decreased below baseline expression with higher doses (50 and 100 J/cm²). Fluorescence intensity of both ABY-029 and IRDye 680LT was highly variable with treatment dose and was not correlative to tumor response. In contrast, the PAI-binding potential (BP) corresponded to the varying EGFR expression measured by pathology. In vivo and ex vivo PAI BP was moderately to highly correlative to percent area IHC EGFR expression (r = 0.65 and 0.54, p < 0.05, respectively) and the in vivo 100 J/cm² treatment group demonstrated significantly lower BP than the controls. PAI emerges as a promising tool for tracking early molecular changes in HNC, with potential clinical applications.

Light-emitting diodes (LEDs) are light sources that can be used for photobiomodulation to treat various diseases and clinical conditions. Growing evidence suggests that photobiomodulation is a promising treatment for rheumatoid arthritis (RA) and osteoarthritis (OA) because of its analgesic and anti-inflammatory effects. However, such evidence is primarily based on studies evaluating low-power laser-based photobiomodulation, and few studies have assessed the efficacy of LED photobiomodulation in the treatment of RA and OA. Thus, this study aimed to review studies on LED photobiomodulation for the treatment of RA and OA, summarizing the irradiation parameters and conditions, and reporting the study types and main results. Studies on the effects of LED photobiomodulation on RA and OA were accessed via PubMed. Data from accessed studies show that LED photobiomodulation has been carried out with red and infrared LEDs based on in vitro and in vivo experimental models. This therapy may decrease arthritic markers, including edema, hyperalgesia, inflammation, cartilage degradation, extracellular matrix alterations, and proinflammatory cytokine levels. LED photobiomodulation could be as effective a therapy as laser photobiomodulation, but further clinical studies are necessary to verify its therapeutic benefits in both RA and OA.

This exploratory in vivo study investigated the impact of solar-simulated ultraviolet (UV) radiation (UVB plus UVA) on the composition of the human skin microbiome in healthy male volunteers. Thirty Caucasian men were exposed to suberythemal and erythemal doses of UV radiation (0.5, 0.7, and 1.0 minimal erythema dose, MED) on defined areas of the lower back. Skin swabs were collected from both irradiated (n = 243) and nonirradiated control sites (n = 81) 30 min, 24 h, and 96 h postexposure. The microbial profiles were generated using flow cytometry, and the data were analyzed via the open-access bioinformatic platform FlowSoFine™. The results revealed pronounced alterations in the microbial composition, with changes already detectable 30 min after exposure. Although partial recovery was observed over time, certain microbial shifts persisted. Further analysis indicated dose-dependent trends in microbiome changes, suggesting a potential relationship between the extent of microbial alteration and the applied UV dose. These results suggest that even low, nonerythematous exposure to solar-simulated UV radiation can rapidly alter the microbial balance of the skin and emphasize the role of UV radiation as a potent modulator of the skin microbial homeostasis.

The oxidation of alcohols to aldehydes is a key transformation in industrial chemistry, as aldehydes are vital intermediates in the synthesis of pharmaceuticals and fine chemicals. Conventional oxidation routes typically employ stoichiometric and corrosive oxidants, generating significant environmental concerns. Greener oxidants such as molecular oxygen (O₂) offer a more sustainable alternative to stoichiometric oxidants; however, their efficient utilization requires activation by catalysts (e.g., Cu-, Pd-, Au-, or Ti-based systems). Homogeneous photocatalysts such as CuCl₂ exhibit promising activity under light irradiation but are limited by challenges in separation and recycling. This study investigates the immobilization of CuCl₂ and TiO₂ (P25) within sodium alginate beads to facilitate photocatalyst recovery and minimize metal leaching. Under UV irradiation for 4 h, benzyl alcohol conversions of 54% (P25) and 49% (CuCl₂) were achieved. Catalyst encapsulation markedly reduced activity due to internal mass transport limitations, as restricted diffusion of O₂ and benzyl alcohol within the bead matrix limited access to active sites and suppressed overall reaction rates. Co-immobilization of P25 and CuCl₂ partially restored conversion (22%), while maintaining high benzaldehyde selectivity (≈1 after 4 h) across all systems. These findings highlight oxygen depletion and mass transfer resistance as key constraints in bead-based photocatalysts. To guide further optimization, a MATLAB-based reactor model incorporating species transport, interfacial mass transfer, and kinetics was developed.

This study assessed the effects of photobiomodulation with 450 and 635 nm laser wavelengths on the release of transforming growth factor-beta (TGF-β), bone morphogenetic protein (BMP)-2, fibroblast growth factor (FGF)-2, and vascular endothelial growth factor (VEGF) from human dental pulp stem cells (DPSCs). In this in vitro study, human DPSCs were cultured and randomly assigned to two experimental groups to undergo 450 and 635 nm laser irradiation with 2, 4, and 6 J/cm² energy densities, and one control group (n = 5). After laser irradiation, total RNA was then extracted, cDNA was synthesized, and expression of TGF-β, FGF-2, BMP-2, and VEGF was assessed by real-time polymerase chain reaction (PCR). Data were analyzed by one-way and two-way ANOVA and Tukey's test (alpha = 0.05). The effects of laser wavelength, energy density, and their interaction were significant on the release of all growth factors (p < 0.0001). Laser irradiation in almost all subgroups increased the release of growth factors. By an increase in energy density, the release of BMP-2 and FGF-2 in both wavelengths, VEGF in the 635 nm group, and TGF-β in the 635 nm group increased while the release of VEGF in the 450 nm group decreased (p < 0.05). The amount of released growth factors in the 635 nm group was higher than in the 450 nm group (p < 0.05). PBMT with 450 and 635 nm lasers increased the release of TGF-β, BMP-2, FGF-2, and VEGF from human DPSCs in most energy densities, which may be of use in regenerative endodontics.

Healthcare-associated infections (HAIs) remain a significant concern in dental settings, especially in light of increasing antimicrobial resistance. This study aimed to characterize and evaluate the efficacy of an ultraviolet C (UV-C) disinfection device specifically developed as an additional resource for dental clinics and healthcare settings. Colorimetric dosimeters were strategically distributed at different points and vertical levels to monitor UV-C radiation distribution in the environment. The emission spectrum and radiation intensity were measured using spectral measurement techniques, while microbiological analyses were conducted on seven commonly encountered surfaces in dental offices using mannitol salt agar selective for Staphylococcus aureus and Staphylococcus epidermidis. The results revealed a significant reduction in colony-forming units (CFUs), exceeding 90% at most sampling points (p < 0.05). An exponential falloff of irradiance with distance from the UV-C source was observed, highlighting the importance of proper positioning of the equipment. Notably, the UV-C device proved effective even on surfaces with higher microbial loads, such as the armrest of the dental chair. The findings demonstrate that both time and distance significantly affect disinfection efficacy, and that purpose-built UV-C devices are viable as complementary tools to conventional chemical cleaning and disinfection protocols.

Photopharmacology achieves precise photo controlled regulation of drug activity by utilizing the properties of photochromic ligands. In this study, a series of novel azobenzene-based photochromic ligands (ABB1-5) were designed and synthesized, and their biological activities were confirmed to be precisely regulated by light irradiation. Bioassays against larvae of Culex pipiens pallens showed that the activity of ABB1 was significantly enhanced after light exposure, with the median lethal concentration (LC₅₀) decreasing from 27.20 μg/mL before irradiation to 16.99 μg/mL after, a reduction of 10.21 μg/mL, yielding a difference coefficient of 1.60. Similarly, experiments on Tetranychus cinnabarinus demonstrated a remarkable decrease in acaricidal activity for ABB4 after irradiation, as evidenced by an increase in LC₅₀ from 7.01 to 18.40 μg/mL, an increase of 11.39 μg/mL, with a difference coefficient of 2.62. Notably, the light-induced differences in activity exhibited by the ABBs series against both C. pipiens pallens larvae and T. cinnabarinus not only validate the potential of photochromic ligands in the precise optical control of drug efficacy but also offer a novel strategy for delaying the development of resistance to acaricides in phytophagous mites.