Photochemical & Photobiological Sciences最新文献

Following the COVID-19 pandemic, portable UV-C radiation sources for disinfection have become increasingly available and integrated into daily life. UV-C devices emitting at 254 nm (mercury lamps) affect skin and eyes, usually causing erythema, burns or photokeratitis. Despite safety recommendations, misuse or accidental exposure remains a risk. Most data on UV-C effects come from cases of accidental overexposure in fixed installations, while portable devices involve different exposure geometry. Users hold the source close throughout the disinfection process, exposing themselves to both direct and reflected UV-C radiation. An in vivo study using male SKH-hr1 mice was conducted in two stages to assess the effects of skin exposure to UV-C radiation from a commercial disinfection device (Hg lamp, 253.7 nm, 5 Wm^-2) under realistic conditions of use. In the first stage, single irradiation doses of 5 Jm^-2, 15 Jm^-2, 30 Jm^-2, 45 Jm^-2 and 60 Jm^-2 were used to determine the minimum erythemal dose. Doses of 45 Jm^-2 and 60 Jm^-2 caused irritation and signs of skin aging including reduced elasticity, wrinkling and dry skin. Based on these findings, the second stage assessed long-term effects with repeated exposures of 45 Jm^-2, 60 Jm^-2, and 100 Jm^-2, irradiating mice 5 times per week for 25 days. Progressive skin damage escalated from mild irritation to significant thickening and premature aging, culminating in erythematous papules indicative of actinic hyperkeratosis. These findings demonstrate that both acute and long-term exposure to UV-C radiation can cause significant skin damage, emphasizing the need for strict adherence to safety guidelines.

Understanding the relationship between molecular structure and bioactivity is crucial for optimizing porphyrin-based therapeutics. By integrating cheminformatics techniques with machine learning models, our work enables the efficient classification of compounds based on their molecular structures and their growth inhibition capabilities (IC₅₀). A dataset of 317 porphyrin derivatives was compiled, incorporating molecular descriptors and biological activity data. Descriptive statistical analysis was performed to examine compound distribution and key features. Clustering analysis was conducted using hierarchical clustering and fingerprint similarity matrices to classify compounds based on structural similarity. Lipinski's Rule of Five was applied to assess drug-likeness, while Murcko scaffold analysis identified core structural patterns. Tumor response data were analyzed to evaluate therapeutic efficacy. Machine learning models were implemented to predict bioactivity. Descriptive statistics highlighted bioactive compounds, with TMPyP4 and Temaporfin being the most studied. Quantitative estimation of drug-likeness and the number of aliphatic carboxylic acids were identified as the most influential descriptors among others for bioactivity. Hierarchical clustering segmented porphyrins into nine structural groups. The analysis identified 168 pIC₅₀ active compounds, with 31 meeting Lipinski's criteria, and 11 overlapping as both effective and bioavailable. Tumor response analysis revealed three porphyrins achieving 100% response. Logistic Regression emerged as the best-performing model, achieving 83% accuracy, demonstrating robust predictive capabilities. This study successfully characterized porphyrin derivatives, reviewing key molecular features influencing bioactivity and evaluating their therapeutic potential. It highlights the potential of machine learning in predicting the biological activity status of porphyrin derivatives.

Neonicotinoid pesticides (NNIs) are widely used worldwide and commonly detected in natural aquatic systems and in engineered systems, including urban or agriculture ponds. We investigated the photoreactivity of DOM and the photodegradation of NNIs in duckweed ponds (DWP) water under simulated sunlight. The molecular composition of DOM in DWP water typically contained more than 65% bulk compositional measurements of lignin-like, terrestrially derived molecules, revealed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). These compounds serve as critical candidates for the oxidizing ³DOM* in the DWP water. The steady-state concentrations of triplet-excited state DOM (³DOM*), singlet oxygen (¹O₂) and hydroxyl radical (^·OH) were measured 6.00 × 10^-14 M, 5.42 × 10^-13 M, and 8.33 × 10^-15 M, respectively, under 5 mg/L [DOC]. Enhanced removal rates of thiamethoxam (TMX) and dinotefuran (DIN) in the irradiated DWP water relative to the purity water demonstrated the importance of indirect photolysis pathways involving photochemically produced ³DOM*and ¹O₂. The findings demonstrated that in DWP water, the photolysis rate constants (k) of TMX and DIN increased to 0.3573 h^-1 and 0.3237 h^-1, respectively. Degradation of imidacloprid was not significantly promoted through the photochemical production of ³DOM* and ¹O₂. Results from this study underscore the role of DOM as photosensitizer in limiting the persistence of NNIs in duckweed ponds through photochemical reactions.

This study investigates the effectiveness of ultraviolet (UV) protection provided by various types of glasses for patients who have orally ingested psoralen. Psoralen is administered orally by patients, as part of PUVA photochemotherapy, 2 h prior to ultraviolet-A exposure. For 12-24 h post psoralen ingestion, there is a potential risk of ocular damage from solar UV (Lerman et al. in J Investig Dermatol 74(4):197-199, 1980). The patients must, therefore, wear eye protection during this period. The purpose of this study was to evaluate the effectiveness of commonly used eyewear for ocular protection during PUVA therapy. A range of glasses, including commercially available sunglasses, prescription sunglasses, prescription glasses without UV protection, and UV protective eyewear, were evaluated. The UV transmission rates of the lenses were measured using a spectrophotometer, followed by a spectroradiometer experiment with a UVA light source to assess the relative UV exposure of the eyewear. The results indicate that while standard UV-protective glasses effectively block UV transmission through the lens, real-world scenarios reveal that inadequate frame coverage can significantly reduce overall eye protection. This highlights the limitation of relying solely on lens transmission as a measure of protection and underscores the critical role of selecting well-designed frames with proper fit for patients during psoralen photosensitisation.

Background: Ulcerative colitis (UC) is a complex inflammatory condition with limited non-invasive tools to monitor early-stage inflammation. This study aimed to investigate the early stages of inflammation in acute and chronic murine models of dextran sulfate sodium (DSS)-induced colitis using in vivo and ex vivo chemiluminescence imaging.

Methods: Two DSS-induced colitis models were used: an acute model over 7 days and a chronic model over 6 weeks. Body weight, stool consistency, and fecal occult blood (FOB) tests were monitored. Chemiluminescence imaging was used to assess inflammation in vivo and ex vivo, complemented by colonoscopy in the chronic model.

Results: In the acute model, DSS-treated mice exhibited weight loss, colon shortening, and positive FOB tests by day 7. Ex vivo chemiluminescence signals exhibited a significant increase as early as day 5 (p < 0.001), while in vivo imaging showed minimal changes. In the chronic model, periodic DSS exposure resulted in recurrent inflammation, with positive FOB tests and significantly elevated ex vivo and in vivo chemiluminescence signals during the final DSS cycle (p < 0.05). Colonoscopy confirmed inflammation progression.

Discussion: This study demonstrates the progression of inflammation in acute and chronic colitis models. However, in vivo chemiluminescence imaging did not reliably detect the onset of inflammation, limiting its application for early-stage disease detection. Ex vivo chemiluminescence and FOB tests provided more consistent insights into inflammation dynamics, addressing the need for improved non-invasive monitoring tools in UC research.

A new symmetrical and a new unsymmetrical Schiff bases are synthesized by condensing 1-(2,4-dihydroxyphenyl)ethanone with, Naphthalen-1-amine and Naphthalen-1,8-diamine under solvent free condition and characterized by IR, UV-visible, ¹H NMR, ¹³C NMR and mass spectral studies. Cation recognizing potentiality of both the Schiff bases is explored-of the Schiff base 4-(1-(naphthalen-1-ylimino)ethyl)benzene-1,3-diol (NEBD) in aqueous methanolic medium and of Schiff base 4,4'-((naphthalene-1,8-diylbis(azanylylidene))bis(ethan-1-yl-1-ylidene))bis(benzene-1,3-diol) (NDBD) is scrutinized in aqueous ACN medium through dual modes namely absorption and emission methods. Both the Schiff base sensors are found to detect Cu(II) ion selectively. The detection occurs in an off-on mode (increase of emission intensity of the Schiff base in the presence of Cu(II) ion) and on-off mode (decrease of emission intensity of the Schiff base in the presence of Cu(II) ion) for the Schiff bases NEBD and NDBD respectively. For the Schiff base NEBD LOD for Cu(II) ion is 1.528 × 10^-6 M and for NDBD it is 2.871 × 10^-7 M. The sensing property is applied in bioimaging technique for the detection of human cancer cells HeLa. Both the Schiff bases are screened for their antimicrobial activities. Schiff base NEBD is found to be more potential than the standard drug amphotericin B towards Aspergillus niger. Regarding Schiff base NDBD, it is as potential as the standard drug towards all the organisms studied.

The introduction of an auxiliary acceptor into donor/acceptor dye systems is one of the most widely used strategies to enhance the light-harvesting properties of dye-sensitized solar cells. However, our understanding of the effects of these auxiliary acceptors remains limited. In this study, we utilize two organic dyes that differ in the positioning of the auxiliary acceptor to explore their impacts on several important factors associated with short-circuit current density and open-circuit photovoltage. These parameters include light-harvesting ability, electron injection, conduction band energy shift and charge recombination. Contrary to common assumptions, we find that the positioning of the alkyl-substituted auxiliary acceptor affects not just the light-harvesting ability but also influences the charge recombination process by altering the dominant conformation of the Hagfeldt donor. Specifically, the auxiliary acceptor situated farther from the Hagfeldt donor is more effective in enhancing the dye's light-harvesting ability compared to those located near the donor end. Conversely, when the auxiliary acceptor is positioned near the Hagfeldt donor and introduces alkyl chains on one side, the two benzene rings substituted with alkoxy groups in the Hagfeldt donor tend to interact with the alkyl chain of the auxiliary acceptor. This interaction hinders the surface protection effect of the Hagfeldt donor and reduces its inhibitory effect on the electron recombination process. These new insights into the effects of alkyl-substituted auxiliary acceptors on inhibiting charge recombination through their influence on the dominant conformation of the Hagfeldt donor opens avenues for the systematic design of high-performance sensitizers.

Photobiomodulation (PBM) has emerged as a promising method for enhancing wound healing. However, a standardized therapeutic protocol has not yet been established. This study aimed to determine the optimal irradiation parameters for wound healing in pigmented hairless mice (SKH-hr2). Mice were irradiated daily with energy doses of 2 or 4 J/cm², achieved with different power densities in each group: 20, 50, or 100 mW/cm². Various methods were used to evaluate the therapeutic efficacy, including histopathological analysis, clinical observation, photo-documentation, assessment of biophysical skin parameters, and Fourier Transform infrared (FT-IR) spectroscopy. The results indicated that the most favorable outcomes regarding wound healing acceleration and inflammation reduction were achieved with an irradiation setting of 50 mW/cm² and 2 J/cm². However, the group subjected to prolonged irradiation times with a power density of 20 mW/cm² and energy of 4 J/cm² exhibited subcutaneous bleeding. The FT-IR spectral absorption bands of amide groups provided important molecular-level information about the secondary structure of collagen, particularly in relation to skin regeneration and the response to applied energy, in agreement with histological data. This study highlights the critical need for further investigation into the parameters of photobiomodulation to ensure its effective application to the different skin phototypes and to mitigate potential adverse effects arising from incorrect usage.

The effects of hydrogen-bonded cysteine (Cys), cystine, and serine (Ser) on the photochemical properties of tryptophan (Trp) enantiomers were investigated at low temperatures in the gas phase. The difference in the relative intensity at 270-280 nm in the ultraviolet photodissociation spectra at 8 K showed that the higher excited states of H⁺(L-Trp) (L-Cys) were red-shifted by stronger intermolecular interactions compared to H⁺(D-Trp) (L-Cys). Photoexcitation of protonated Trp enantiomers hydrogen-bonded to Cys and cystine led to detachment of the hydrogen-bonded molecules. The relative abundance of the NH₂CHCOOH loss from H⁺(D-Trp) (L-Ser) was higher than that of the loss from H⁺(L-Trp) (L-Ser) in the product ion spectra obtained by 285 nm photoexcitation, indicating that hydrogen bonding with L-Ser induces the enantiomer-selective photodissociation of Trp. The photodissociation spectra for the S₁-S₀ transition of H⁺(L-Trp) (L-Ser) at 8-100 K showed the conformational changes to the conformers with weaker intermolecular interactions at high temperatures. In terms of their influence on the photochemical properties of Trp enantiomers at low temperatures in the gas phase, Cys and Ser can be classified as the same type of alanine and leucine, respectively.

In recent years, tungsten disulfide (WS₂), a type of 2D nanomaterial, has garnered significant attention as a promising new material due to its unique properties. Research efforts are underway to explore its various applications. In this study, we employed a liquid-phase laser ablation technique using two different pulse lasers, with a 10 ns or 130 fs pulse duration, to fabricate WS₂ nanostructures and conducted thorough evaluations of their physical properties. Additionally, we fabricated and evaluated WS₂-gold nanocomposites by decorating WS₂ with gold nanoparticles. Femtosecond transient absorption measurements revealed that in samples subjected to the shorter pulse width, the free carrier relaxation rate up to recombination was slower, with free carriers disappearing within tens of picoseconds, leaving only trapped species as long-lived entities. Furthermore, in gold-decorated samples, the interaction between gold nanoparticles and WS₂ suggested that excited electrons underwent interfacial charge transfer and formed charge separated states, resulting in a slower relaxation time before recombination.