Journal of photochemistry and photobiology. B, Biology最新文献

A green sol-gel method was utilized to produce a Zr-decorated TiO₂ nanocomposite exhibiting improved photocatalytic and biological activity under visible light irradiation. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) provided structural and morphological characterisation, confirming the coexistence of anatase and rutile phases, with acidic conditions (pH 2) promoting rutile production. Diffuse reflectance spectroscopy (DRS) demonstrated altered optical properties due to Zr inclusion and nanoscale phenomena. The photocatalytic efficacy was assessed via the degradation of Brilliant Green dye, revealing that the Zr-TiO₂ nanocomposite demonstrated much superior performance compared to pristine TiO₂, especially under solar illumination, due to enhanced visible-light absorption and charge separation. Operational parameters, such as solution pH, were tuned to improve degrading efficiency. In addition to photocatalysis, the nanocomposite exhibited significant antibacterial and antifungal properties, an elevated antioxidant capacity of 89.4%, and remarkable anti-inflammatory benefits. In vitro cytotoxicity investigations demonstrated selective anticancer efficacy against MCF-7, KB, and HepG2 cell lines, while displaying no harm towards normal NHDF B cells. These results underscore the promise of Zr-TiO₂ nanocomposites for combined environmental remediation and photobiological applications.

This study reports the synthesis and characterization of fungal carbon dots (F-CDs) derived from filamentous microfungi belonging to the subphylum Pezizomycotina. Carbon dots were synthesized from a cell-free aqueous fungal homogenate obtained from the mycelial biomass of Phialomyces macrosporus, Penicillium spp., and Fusarium sp. The water-soluble mycelial fraction, containing intracellular metabolites, soluble proteins, and other low-molecular-weight compounds released upon cell disruption, was used directly as a carbon precursor in a hydrothermal synthesis. The resulting F-CDs exhibited intense green fluorescence with excitation-dependent emission, as confirmed by UV-Vis absorption and photoluminescence spectroscopy. Transmission electron microscopy revealed spherical nanoparticles with an average diameter of 3.9 ± 1.1 nm and crystalline domains with an interplanar spacing of 0.26 nm. Zeta potential measurements indicated negatively charged surfaces (-15.6 to -18.4 mV), suggesting good colloidal stability and potential for biological interactions. Fluorescence microscopy demonstrated efficient uptake of F-CDs by Aspergillus niger hyphae, resulting in bright green staining and indicating high cellular compatibility. These results establish filamentous microfungi as previously unexplored and versatile carbon precursors for the sustainable production of green-emitting carbon dots with promising applications in bioimaging.

Excessive use of antibiotics contributes to the development of multidrug-resistant microorganisms, making bacterial infections more difficult to treat. As an alternative method, photodynamic therapy is being explored. This therapy relies on generating cytotoxic concentrations of reactive oxygen species (ROS) during the interaction of a photosensitizer with light and molecular oxygen. In the presented work, we investigated the antibacterial efficacy of four different photosensitizers: 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TmPyP), 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin zinc (ZnTPPS), zinc phthalocyanine disulfonate (ZnPcS), and tetramethylthionine chloride (methylene blue, MB) on Escherichia coli. The results showed that this type of bacteria is susceptible to all of the studied photosensitizers. Our measurements revealed that a bacteriostatic or bactericidal effect can be achieved either by exposure to high-dose (50 J/cm²) violet (414 nm) light or by combining high-dose violet light with TmPyP or ZnTPPS. However, when using red-light-sensitive ZnPcS or MB, significant inhibition of bacterial growth occurred after three cycles of light exposure at a relatively low individual light dose (10 J/cm²), rather than a single high dose (50 J/cm²). Additionally, the fluorescent probe CellROX Red, which monitors ROS production, showed a significant increase in fluorescence in the presence of porphyrin photosensitizers as early as after the first irradiation.

Photobiomodulation (PBMT) speeds up wound healing, partly by attracting pericytes. However, its specific mechanisms in a diabetic setting are still not well understood. We studied tissue regeneration after PBMT using a transgenic mouse model (NG2⁺DsRed/Nestin⁺GFP) with streptozotocin-induced Type 1 diabetes. PBMT was applied daily (660 nm, 20 mW, 7 s, 0.14 J, 0.71 W/cm², 5 J/cm²). Our results showed increased lumen area of pericyte-covered vessels and significant flow of perivascular and neural progenitor cells in PBMT-treated wounds. We also saw an increase in the pro-resolving cytokine IL-1RA after irradiation. PBMT did not change levels of GLUT1, TNF, IL-1α, or NF-κB in the chronic inflammatory environment. Diabetic cells treated with PBMT showed limited proliferation and migration but had improved ability for adipogenic differentiation. Despite only modest changes in the inflammatory microenvironment, photobiomodulation notably accelerates tissue repair by directly encouraging pericyte and neural progenitors entry into the wound bed.

Objective: Ultra-weak Photon Emission (UPE) is thought to represent chemiluminescence from oxidative metabolic processes. This study aimed to characterize UPE dynamics during transient ischemia and reperfusion, while systematically assessing the reproducibility of both baseline and intervention-induced UPE measurements.

Methods: UPE was recorded from the hands of 30 participants across two separate sessions using a custom-built photon-counting system. Transient ischemia was induced by a two-minute upper-arm tourniquet application. The stability and reproducibility of these measurements were evaluated using Bland-Altman analysis, Pearson correlations, and within-subject Coefficient of Variation (wsCV).

Results: UPE intensity exhibited a distinct multiphasic response to blood flow restriction: A sharp decline during ischemia (reaching ∼85% of baseline) followed by stabilization during reperfusion at approximately 95% of baseline. Baseline measurements exhibited high intrasession reproducibility (r = 0.97, wsCV = 11.3%) but only moderate intersession reproducibility (r = 0.59, wsCV = 34.4%). During the intervention, reproducibility was moderate in the ischemic phase (r = 0.66, wsCV = 43.6%), whereas the reperfusion phase showed substantially greater variability (r = 0.32, wsCV = 99.9%). In contrast, normalized AUC quantification produced stronger intersession linear associations and improved reproducibility across both the baseline-ischemia (r = 0.83, wsCV = 28.3%) and reperfusion segments (r = 0.80, wsCV = 35.1%).

Conclusions: UPE is able to capture a dynamic physiological response to blood flow restriction that follows a consistent temporal trend despite significant individual variability. This study establishes quantitative benchmarks for UPE measurement stability, positioning it for future consideration as a non-invasive tool for monitoring oxidative metabolic activity in vivo.