Photochemistry and Photobiology最新文献

Photodynamic therapy (PDT) effectively kills cancer cells and initiates immune responses that promote anticancer effects locally and systemically. Primarily developed for local and regional cancers, the potential of PDT for systemic antitumor effects [in situ photo-vaccination (ISPV)] remains underexplored. This study investigates: (1) the comparative effectiveness of paclitaxel (PTX) prodrug [Pc-(L-PTX)₂] for PDT and site-specific PTX effects versus its pseudo-prodrug [Pc-(NCL-PTX)₂] for PDT combined with checkpoint inhibitors; (2) mechanisms driving systemic antitumor effects; and (3) the prophylactic impact on preventing cancer recurrence. A bilateral tumor model was established in BALB/c mice through subcutaneous injection of CT26 cells. Mice received the PTX prodrug (0.5 μmole kg^-1, i.v.), and tumors were treated with a 690-nm laser (75 mW cm^-2 for 30 min, drug-light interval 0.5 h, light does 135 J cm^-1), followed by anti-CTLA-4 (100 μg dose^-1, i.p.) on days 1, 4, and 7. Notable enhancement in both local and systemic antitumor effectiveness was observed with [Pc-(L-PTX)₂] compared to [Pc-(NCL-PTX)₂] with checkpoint inhibitor. Immune cell depletion and immunohistochemistry confirmed neutrophils and CD8+ T cells are effectors for systemic antitumor effects. Treatment-induced immune memory resisted newly rechallenged CT26, showcasing prophylactic benefits. ISPV with a PTX prodrug and anti-CTLA-4 is a promising approach for treating metastatic cancers and preventing recurrence.

Rose bengal (RB) is a widely used photosensitizer for determining quantum yields of singlet oxygen generation. While it is known to aggregate in polar environments at concentrations above 2 μM, the relationship between RB concentration and singlet oxygen photogeneration remains unclear. This study investigates the shift from monomeric to dimeric RB with increasing concentration and its impact on singlet oxygen generation in D₂O-based solutions and DMPC liposomes. Absorbance maxima for RB were observed at 514 nm (dimer) and 549 nm (monomer), with ionic environments influencing aggregation rates. Singlet oxygen phosphorescence showed non-linear dependency above 2 μM, indicating the effects of aggregation. Results suggest that RB concentrations should be kept at 1 μM or lower in photochemical studies to avoid aggregation-related discrepancies in singlet oxygen yield determination. These findings highlight the importance of considering RB aggregation in photochemical research and medical applications.

Spectroradiometry, radiometry, and dosimetry are employed for the measurement of ultraviolet radiation (UVR) irradiance and non-ionizing exposure. Different types of UVR dosimeter have been developed for measuring personal and environmental UVR exposures since film dosimetry was pioneered in the 1970s. An important type of dosimeter is the thin film variant, which contains materials that undergo changes in optical absorbance when exposed to UVR. These changes can be measured at a specific wavelength using a spectrophotometer. Thin film dosimeters allow UVR exposure measurements on humans at various body sites during daily activities, as well as on plants, animals, and any sites of interest when utilized in a field environment. This review examines the properties and applications of five types of thin film UVR dosimeter that have different dynamic exposure limits and spectral responses. Polysulphone, with a spectral response approximating the human erythema action spectrum, was one of the first materials employed in thin film form for the measurement of UVR exposures up to 1 day, and up to 6 days with an extended dynamic range filter. Polyphenylene oxide has been characterized and employed for personal UVR exposure measurements up to approximately four summer days and has also been used for long-term underwater UVR exposures. Phenothiazine and 8-methoxypsoralen have been reported as suitable for the measurement of longer wavelength UVA exposures. Finally, polyvinyl chloride with an extended dynamic exposure range of over 3 weeks has been shown to have predominantly a spectral response in the UVB and extending up to 340 nm.

This study assessed the effects of red and green LEDs on mast cells (MCs) in third-degree burns in 75 Wistar rats, divided into control, red LED (RED), and green LED (GREEN) groups. Animals were irradiated daily with RED (630 nm, 300 mW, 0.779 W/cm², 9 J/cm², 30 s) and GREEN (520 nm, 180 mW, 0.467 W/cm², 60 J/cm², 30 s). Histological sections stained with toluidine blue were analyzed for total and subtype MCs. Standardized MC counting was performed across the viable lesion area, considering lesion margins, through intact connective tissue and the integrity of skin appendages. No statistically significant differences in MCs 2 (with released granules and intact cell border) were found between groups. Irradiated groups showed increased total MCs at 7, 14, and 21 days (p < 0.05), with a decrease in MCs 1 (intact MCs) at all time points compared to control (p < 0.05). Significant changes in MCs 3 (with massive degranulation and partial or complete disintegration of the cell border) degranulation were noted in RED at 7, 14, and 21 days (p < 0.009) and in GREEN at 14 (p < 0.009) and 32 days (p < 0.028). Results suggest red and green LEDs modulate MC recruitment and degranulation in third-degree burns.

Consuming microbiologically-contaminated water is the primary cause of many water-borne diseases and deaths worldwide. Governments aim at providing drinking water for vulnerable populations, especially through low-cost interventions. Therefore, the solar disinfection (SODIS) of such pathogens provides a simple and cost-effective way to obtain good quality water. In this procedure, PET bottles are filled with contaminated water and exposed to sunlight for 1-2 days. To accelerate decontamination, methylene blue (MB) dye added as a photocatalyst, boosts singlet oxygen generation upon absorbing red-band sunlight. This study explores the use of a Sunlight Simulator (SSL) device to research and standardize the SODIS method with a vital dye as MB. PET bottles were filled with artificially-contaminated water with Streptococcus epidermidis and Deinococcus radiodurans Gram-positive bacteria, Escherichia coli and Salmonella typhimurium Gram-negative bacteria, or bacteriophage λ as well. In all experiments, 50 ng/mL MB ensued a synergistic lethal effect after SSL exposure. The results indicate that bacterial and bacteriophage inactivation can be achieved in shorter times with MB-SSL treatment compared to SSL without MB. In this sense, when compared to previous sunlight-SODIS results, the SSL source is a reliable tool to study the parameters of both SODIS and MB-SODIS protocols, and also a feasible tool to afford assays whenever there are unfavorable climate conditions.

Clothianidin (CL) is a neonicotinoid insecticide widely used in crop protection against insect pests. However, its effects on photosynthesis remain largely unknown. Here, by investigating the influence of CL at the concentrations of 22 and 110 μg/L on the primary processes of photosynthesis, membrane fluidity and structural changes of pea chloroplasts, we located several primary binding sites of this pesticide. Similar dynamics were observed for both concentrations. However, statistically significant differences were only found at 110 μg/L for all methods used. The light saturated rate of linear electron flow decreased mainly due to the disturbance of electron flow on the acceptor side of photosystem II (PSII) associated with the appearance of Q_B-nonreducing centers and empty Q_B binding sites of PSII. The functioning of the donor side of PSII, the activity of photosystem I (PSI) and the maximum quantum yield of PSII photochemistry (Fv/Fm) were not found to be significantly altered. Increased membrane fluidity and structural alterations of the thylakoid membrane led to a decrease in the development of the proton gradient ΔрН and membrane energization processes.

Combining photodynamic antimicrobials with nonwovens is prospective. However, common photosensitizers still have drawbacks such as poor photoactivity and the inability to charge. In this study, a photodynamic and high-efficiency antimicrobial protective material was prepared by grafting bis benzophenone-structured 4,4-terephthaloyl diphthalic anhydride (TDPA) photosensitizer, and antimicrobial agent chlorogenic acid (CA) onto spunbond-meltblown-spunbond (SMS) membranes. The charging rates for ^·OH and H₂O₂ were 6377.89 and 913.52 μg/g/h. The light absorption transients structural storage remained above 69% for 1 month. High electrical capacity remained after seven cycles indicating its rechargeability and recyclability. The SMS/TDPA/CA membrane has excellent bactericidal performance when under illumination or lightless conditions, and the bactericidal efficiency of Escherichia coli and Staphylococcus aureus reached over 99%. The construction of self-disinfection textiles based on the photodynamic strategies proposed in this paper is constructive for expanding and promoting the application of textile materials in the medical field.

Prolonged endoplasmic reticulum (ER) stress contributes to cell apoptosis and interferes with bone homeostasis. Although photobiomodulation (PBM) might be used for ER stress-induced diseases, the role of PBM in relieving cell apoptosis remains unknown. During ER stress, glycogen synthase kinase-3β (GSK-3β) is critical; however, its functions in PBM remain uncertain. Thus, this study aimed to investigate the role of GSK-3β in 625 nm light-emitting diode irradiation (LEDI) relieving tunicamycin (TM)-induced apoptosis. Based on the results, pre-625 nm LEDI (Pre-IR) phosphorylated GSK-3β via ROS production. Compared with the TM group, Pre-IR + TM group reduced the phosphorylation of the α-subunit of eukaryotic translation initiation factor 2 (eIF-2α) and B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax)/Bcl-2 ratio through regulating GSK-3β. Furthermore, a similar tendency was observed between Pre-IR + TM and Pre-LiCl+TM groups in preventing TM-induced early and late apoptosis. In summary, this study suggests that the Pre-IR treatment in TM-induced ER stress is beneficial for preventing cell apoptosis via GSK-3β phosphorylation.

The field of sun protection is quickly changing and the research article by Douki et al., published in the current issue of Photochemistry and Photobiology, reported key experimental data that will certainly help the development of better sun care products. Mutagenic photoproducts (CPDs, cyclobutane pyrimidine dimers and 6-4PPs, pyrimidine-6-4-pyrimidone photoproducts) were formed in the reconstructed human epidermis (RHE) by UVB (312 nm) irradiation, and their concentrations were detected by HPLC-MS/MS as a function of time after the UVB treatment. RHE had been previously exposed or not (control) to blue light (427 nm). Both CPDs and 6-4PPs were shown to last longer in blue-light irradiated RHE, proving the inhibition of the DNA repair by blue light exposure. This is a highly relevant information because sunscreens allow people to enjoy longer periods under the sun and consequently, to endure very high doses of blue light. The work also reported results obtained with RHEs previously treated with a sunscreen formulation containing a broadband filter that offers blue-light protection. Interestingly, authors observed that the DNA repair was not significantly inhibited in RHE previously treated with the sunscreen offering broadband protection. Readers will find a scientifically sound proof of the importance of blue-light protection in sun care products.

Apart from biocompatibility, ZnO quantum dots (QDs) are considered to be an efficient luminescence material due to their low cost and high redox potential. Here, we report the synthesis of ZnO QDs by using five different functionalizing ligands like mercaptoacetic acid (MAA), 3-mercaptopropionic acid (MPA), octadecene (ODE), ethylene glycol (EG), and oleyl amine (OLA) and fabricate their assemblies with graphene oxide (GO). We investigate the role of functionalizing ligands as a surface modifier of ZnO QDs for their attachment to GO. The steady-state photoluminescence (SSPL) and time-resolved photoluminescence (TRPL) analyses demonstrate the photoluminescence (PL) quenching of ZnO QDs in ZnO QDs-GO assembly. The highest reduction in PL intensity is observed with ZnO QDs-GO assembly with EG as a surface functionalizing ligand. Cyclic voltammetry (CV) analysis confirms the feasibility of charge transfer from ZnO QDs to the GO. The maximum (79.43%) charge transfer efficiency (E_CT) is observed in the case of ZnO-MAA-GO as compared to other assemblies. This means the thiol group-containing ligands facilitate charge transfer as compared to hydroxyl and amine group ligands. This leads to the conclusion that charge transfer in ZnO QDs-GO assemblies depends strongly on the nature of surface ligands.