Search Results (420)

Pure Bi₂O₃ is a favorable photocatalyst for visible-light-driven processes; however, the rapid recombination of photogenerated charge carriers limits its practical performance. In this work, Co-doped Bi₂O₃ nanoparticles, Co_xBi_2−xO₃ (x = 0–0.1), were produced through a sol–gel combustion route to enhance their visible-light photocatalytic activity. As demonstrated by XRD analysis, Co was successfully incorporated into the Bi₂O₃ lattice, along with changes to the crystal structure, crystallite size (up to ~88 nm), and lattice strain. Optical measurements revealed that Co-doping induces a clear absorption edge’s red shift, resulting in a systematic reduction of the optical band gap from 3.9 eV for pure Bi₂O₃ to approximately 3.1 eV for the doped samples. This band gap narrowing enhances visible-light absorption and improves photocatalytic efficiency. Photocatalytic activity was assessed by measuring the degradation of MB under visible-light irradiation. Incorporation of Co consistently enhanced the performance across all doped samples compared to the pristine oxide counterpart. The Co_0.1Bi_1.9O₃ composition demonstrated the best performance, achieving a removal efficiency of 94.5% within 120 min, compared with 73.0% for pure Bi₂O₃. Kinetic analysis indicated pseudo-first-order behavior, with the optimal sample showing a rate constant of 0.0240 min⁻¹—more than twice that of the undoped material (0.0105 min⁻¹). These results validate that Co-doping is an actual approach for engineering the electronic structure of Bi₂O₃, leading to enhanced visible-light absorption, improved charge-carrier separation, and significantly higher photocatalytic efficiency for environmental remediation applications. Full article

Acaryochloris marina is a distinctive cyanobacterium that uses chlorophyll d as its primary photosynthetic pigment and possesses two major light-harvesting systems: membrane-integral chlorophyll-binding Pcb/CBP complexes and water-soluble phycobiliproteins. How these antenna systems respond at the transcriptome level to contrasting light environments remains incompletely characterized. Here, we re-analyzed a publicly available RNA-seq dataset for A. marina MBIC11017 (NCBI BioProject PRJNA1130970), comparing cells grown under low-irradiance far-red light (LL-FR; 1.5–2 µmol photons m⁻² s⁻¹, 710-nm peak) and high-irradiance white light (HL-WL; 30–35 µmol photons m⁻² s⁻¹). Because light quality and irradiance both differ in this experimental design, the two effects cannot be separated; all transcriptional changes are therefore interpreted as responses to the combined LL-FR versus HL-WL contrast rather than to far-red wavelength alone. Of 8439 expressed genes, 1810 (21.4%) were significantly differentially expressed (adjusted p < 0.05). Using GFF-verified locus tags which corrected mis-annotations propagated in earlier analyses, the PS-I core gene set showed a mean log₂ fold-change of +1.96 (3.9-fold; 11/11 loci significant), whereas the PS-II core gene set showed a mean log₂ fold-change of +1.10 (2.1-fold; 12/20 loci significant). Light-harvesting genes showed the strongest response: 17/18 phycobiliprotein-pathway genes in KEGG amr00196 were upregulated, together with multiple putative Pcb/CBP loci (mean antenna log₂FC = +3.51; 11.4-fold). Weighted gene co-expression network analysis placed the antenna-associate genes examined here within a module positively correlated with the LL-FR condition (r = 0.802, p = 0.017), and STRING analysis supported an enriched network of predicted or known protein associations (1115 nodes, 4763 edges; PPI enrichment p < 1.0 × 10⁻¹⁶). Recent matched-irradiance experiments indicate that, at equal photon flux, far-red wavelengths reduce phycobilisome content relative to white light. The transcriptional pattern reported here is therefore most parsimoniously interpreted as predominantly a low-irradiance response, with possible wavelength-associated CA5 contributions that cannot be isolated in the present design. Overall, the analysis reveals coordinated transcript-level changes across plasmid-encoded reacquired phycobiliprotein genes, chromosomal Pcb/CBP loci, chlorophyll biosynthesis genes, and photosystem core genes, consistent with coordinated regulation of light-harvesting components in A. marina. Full article

In this study, we report the synthesis and characterization of three Cu(I) complexes bearing functionalized dipyridylamine ligands and DPEphos. Structural analysis confirms a distorted tetrahedral coordination environment around the metal center. Photophysical studies in DMSO show similar absorption profiles (λ_abs ≈ 341–343 nm) with ligand-centered and MLCT transitions, while emission spans the visible region (λ_emi = 410–483 nm) and is strongly influenced by ligand substitution, with the CF₃ derivative displaying a marked red shift. Emission is insensitive to oxygen and exhibits short lifetimes (τ ≈ 14.9–15.3 ns), suggesting short-lived ¹MLCT excited states. Biological evaluation in A375 melanoma cells reveals that all complexes exhibit low-micromolar cytotoxicity under dark conditions (IC₅₀ = 3.33–4.92 μM). Notably, only the CF₃-substituted complex shows a significant light-induced enhancement of activity upon irradiation at 390 nm (IC₅₀ = 1.18 μM), indicating photoactivation. Full article

Phycobiliprotein linker polypeptides (PBLPs) are essential structural components of phycobilisomes (PBS), yet their composition, evolutionary trajectories, and regulatory functions in Pyropia haitanensis remain poorly understood. Here, we performed the first genome-wide identification and functional characterization of PBLPs in P. haitanensis. Nineteen PBLP genes were identified and classified into three subfamilies (LR, LRC, LC), exhibiting substantial physicochemical diversity and distinct gene structures. Phylogenetic and synteny analyses revealed extensive paralogous diversification driven primarily by dispersed duplication, with most duplicated pairs under strong purifying selection. Notably, the LCM subfamily was absent in P. haitanensis and P. yezoensis, suggesting lineage-specific gene loss and potential neofunctionalization of LR/LRC members. Transcriptome profiling demonstrated pronounced expression divergence between the wild-type (ZD) and red pigment mutant (RED) strains, with six PBLP genes showing significant differential expression validated by qRT-PCR. Under five irradiance levels, PBLP genes displayed distinct light-responsive transcriptional patterns. Mantel tests further revealed strong associations between PBLP expression and phycobiliprotein contents, photosynthetic pigments, and chlorophyll fluorescence parameters, indicating functional specialization within the family. Overall, this study provides comprehensive insights into the evolution, expression dynamics, and regulatory potential of PBLPs in P. haitanensis, highlighting their central roles in PBS assembly, pigment metabolism, and photophysiological acclimation. These findings establish a foundation for elucidating PBS regulatory mechanisms and improving pigment-related traits in economically important red algae. Full article

To investigate the differences in reactive oxygen species (ROS) metabolism and signal transduction between the illuminated and non-illuminated surfaces of mangoes exposed to red light, this study used “Tainong No.1” mangoes as the test material, setting up three groups: mango exposed to red light, mango without red light and mango in darkness. The study measured maturity physiological indicators, ROS content, antioxidant enzyme activity, non-enzymatic substances, and combinations with DIA proteomics analysis. The results showed that red light exposure promoted the overall ripening of mangoes, and there was almost no difference in ripening between mango exposed to red light and mango without red light. Red light mainly induced rapid accumulation of hydrogen peroxide in the peel of the irradiated area and stimulated the synthesis of superoxide anion in the pulp. The antioxidant capacity of both the irradiated and non-irradiated areas was enhanced. Key proteins in the ROS signaling pathways such as Rab11, LRK-RLK, and PIN3 were significantly upregulated. In summary, red light promotes synchronous ripening of mango fruits by coordinately regulating the ROS homeostasis of the tissue, and provides new insights into the use of light signals for regulating fruit metabolism. Full article

The expression of two genes, Fum1 and Fum2, encoding the mitochondrial and cytosolic forms of fumarase (EC 4.2.1.2); the methylation of individual CpGs of their promoters; and fumarase activity were studied in sunflower (Helianthus annuus L.) leaves depending on irradiation and salinity. Fumarase activity was twice as high in darkness compared to irradiation by white light and red light, while far-red light applied after darkness or after red light reverted the activity to the values in darkness, which indicates the involvement of phytochrome. Using qRT-PCR, it was demonstrated that this corresponded to the pattern of expression of the Fum1 gene, while the expression of the Fum2 gene was higher upon irradiation by white and red light, and lower in darkness and under far-red light. Under the application of 150 mM NaCl for 1, 3, 6, 12, and 24 h, fumarase activity increased fivefold from the start of incubation to 6 h, and then decreased after 12 h. These changes were associated with the transcriptional regulation of the Fum1 and Fum2 genes. Changes in the methylation status of the analyzed CpGs in their gene promoters, detected via semi-quantitative methylation-specific PCR, were associated with differences in their expression. The higher methylation levels of the analyzed CpGs in the Fum1 gene promoter under different light conditions and in the Fum2 gene promoter under salinity corresponded to low levels of their transcripts in sunflower leaves. It is suggested that the mitochondrial and cytosolic forms of fumarase are regulated by light and salinity at the gene expression level, presumably through changes in the methylation status of individual CpGs in their promoters. Full article

Photobiomodulation (PBM), the therapeutic application of red to near-infrared light, has demonstrated neuroprotective effects in preclinical CNS models, yet clinical translation remains inconsistent. This systematic review synthesises evidence for PBM across CNS applications to identify factors associated with therapeutic response. We searched five databases (MEDLINE, Embase, CENTRAL, Web of Science, Scopus) through January 2025 following PRISMA 2020 guidelines. Included studies employed PBM for CNS conditions with quantified neurological, cognitive, or functional outcomes; evidence quality was assessed using RoB 2, ROBINS-I, SYRCLE, and the GRADE framework. Thirty studies met inclusion criteria: 27 human studies (n ≈ 2244 participants) and 3 animal studies spanning Alzheimer’s disease, Parkinson’s disease, stroke, traumatic brain injury, and other CNS conditions. Dosimetry—particularly irradiance and light source type (laser vs. LED)—appears to be the primary factor associated with efficacy for Alzheimer’s disease (GRADE: Moderate); trans-cranial LED shows promise for Parkinson’s disease (GRADE: Low); trans-cranial 808 nm laser demonstrates no benefit for acute ischaemic stroke (GRADE: High). Systemic abscopal mechanisms may offer additional therapeutic pathways warranting investigation. These findings provide a condition-specific framework for rational PBM protocol development, supporting adequate irradiance via laser or intra-nasal delivery for Alzheimer’s disease, LED-based trans-cranial protocols for Parkinson’s disease, and integration of artificial intelligence for personalised optimisation. Full article

This work presents a novel one-step plasma–solution synthesis of Prussian Blue (PB) and copper hexacyanoferrate (Cu-PBA) nanoparticles via underwater pulsed DC discharge. For the first time, the direct plasma-assisted formation of these coordination polymers is reported. The obtained materials were examined by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy (SEM). These analyses confirmed that the desired phases had formed, along with small amounts of oxide byproducts (α-Fe₂O₃, CuO) arising from the erosion of the electrodes. Photocatalytic activity was evaluated through the degradation of organic dyes (Reactive Red 6C, Rhodamine B, and Methylene Blue) under UV-light irradiation. Both catalysts achieved complete dye degradation within 90 min of UV irradiation (after an initial 30 min dark adsorption step, total experiment time 120 min). Notably, selective performance was observed: PB exhibited higher activity toward the cationic dye Methylene Blue, while Cu-PBA was more effective for the anionic dye Reactive Red 6C. This selectivity is attributed to the specific oxide impurities forming heterojunctions that facilitate charge separation and generate distinct reactive oxygen species. The plasma–liquid method offers a rapid and environmentally benign route to functional PBA-based composites, with potentially scalable characteristics pending further engineering optimization. These findings highlight the potential of utilizing synthesis-induced impurities to tailor photocatalytic selectivity for water purification applications. Full article

The growing demand for sustainable water treatment technologies requires photocatalysts that combine low environmental impact, energy efficiency, and mechanistic robustness. In this work, $Ag/Zn$ nanocomposites were green-synthesized using Chlorella vulgaris polar extract as a bio-mediated reducing and stabilizing agent, eliminating hazardous reagents and high-energy processing steps. Structural characterization (XRD, FTIR, SEM, UV–Vis) confirmed the coexistence of crystalline wurtzite $ZnO$ with metallic $Ag$ and ${Ag}_{2}O$ phases. Photocatalytic activity was evaluated through Congo Red degradation under a sequential dark–light protocol, enabling clear separation of adsorption and photoactivated pathways. During the $60 \mathrm{m}\mathrm{i}\mathrm{n}$ dark stage, removal remained limited ($~9–11\%$), consistent with adsorption–desorption equilibration. Upon UV irradiation, a distinct kinetic transition occurred, leading to final removal efficiencies of $44–49\%$ after $180 \mathrm{m}\mathrm{i}\mathrm{n}$. Notably, performance remained stable across the investigated photon flux range, indicating operation beyond a strictly photon-limited regime and highlighting an intrinsically energy-resilient catalytic response. A mechanistic kinetic model integrating reversible adsorption with light-dependent degradation accurately reproduced all experimental profiles ($NRMSE=3.14\%$) and successfully predicted an independent dark-control experiment without additional fitting. By coupling green synthesis with quantitative kinetic validation, this study proposes a sustainability-oriented framework for designing photocatalysts that align low-impact fabrication with energy-conscious water remediation. Full article

In the current research, graphene and cellulose nanocrystals (CNCs) loaded with silver nanoparticles were synthesized using the hydrothermal method with different mass ratios (G:CNC:CS). The composite GC2 (1:0.2:0.2) (MIC = 6.1 µg·mL⁻¹) and GC3 (1:0.3:0.3) (MIC = 1.8 µg·mL⁻¹) exhibited the maximum antibacterial activity against Staphylococcus aureus subsp. aureus ATCC BAA-977 and Pseudomonas aeruginosa, respectively. The antibacterial performance underscores the complex interplay between the compositional attributes of GC2 and GC3, and the unique susceptibility profiles of different bacterial strains. The antibacterial mechanism was proposed to understand the antibacterial activity process. Ag⁺ cations and reactive oxygen species (ROS) formed with the composite materials are responsible for disrupting interactions with the bacterial cell wall via transmembrane proteins. Eriochrome Black T exhibited the highest photocatalytic degradation efficiency (~90% under UV), followed by Congo Red, which also showed substantial removal across all irradiation conditions. In contrast, Bisphenol A and tetracycline displayed comparatively lower degradation efficiencies, particularly under UV light. Overall, the degradation trend for all pollutants followed the order: UV > solar > visible irradiation. Full article

The increasing demand for better dental aesthetics has driven the development of tooth-whitening techniques that are effective while reducing invasiveness. Hydrogen peroxide (HP) and carbamide peroxide (CP) continue to be the most common active ingredients in bleaching products. Various types of light and laser activation have been introduced to speed up the bleaching process and decrease clinical application time. However, published results regarding their effectiveness and biological safety are inconsistent and sometimes contradictory. Aim: The objective of this study was to identify irradiation conditions that optimise the whitening performance of peroxide-based bleaching agents while ensuring safety for dental hard tissues and ocular structures. This objective was achieved through a systematic synthesis and meta-analyses of both experimental and clinical evidence on bleaching techniques, light or laser activation, and related treatment outcomes. Additionally, the study aimed to provide an integrated overview of currently used irradiation technologies, bleaching agents, treatment protocols, and relevant safety considerations. Methods: A multi-stage analytical approach was employed. Evidence was collected from systematic reviews, randomised and non-randomised clinical trials, and laboratory-based in vitro investigations. The studies assessed differences in bleaching agents (HP and CP), their concentrations, and application protocols, as well as various activation systems, including halogen lamps, conventional LEDs, violet LEDs, metal–halide lamps, and laser wavelengths such as visible blue (~440 nm), red or near-infrared (~1.7 µm), and other spectral ranges. Extracted outcome measures included tooth colour improvement (ΔSGU, ΔE), incidence of tooth sensitivity, changes in enamel surface morphology, temperature increases in the pulp chamber, and the bond strength of restorative or orthodontic materials. When methodological compatibility permitted, quantitative synthesis and meta-analysis were conducted to estimate the effects of activation modalities and irradiation parameters. Results: Analysis of data from 28 systematic reviews and numerous clinical and laboratory studies showed that the degree of colour improvement did not consistently rely on peroxide concentration or on whether bleaching was performed in-office or through home-based protocols. In most studies, adding light activation did not produce a clearly superior whitening effect compared to chemically driven bleaching alone. However, certain laser-assisted methods—especially those using blue diode lasers around 440 nm or near-infrared diode lasers near 1.7 µm—were linked with faster whitening responses and, in several in vitro experiments, fewer enamel surface irregularities. Increases in pulp temperature remained below the generally accepted safety threshold of 5.5 °C in the reported experimental conditions. While laser activation reduced treatment time, some studies observed a temporary decrease in the bond strength of orthodontic brackets following bleaching. Photobiomodulation techniques seem promising for reducing post-treatment sensitivity, although more robust clinical evidence is still needed. Conclusions: Targeted activation with diode lasers, especially within the blue and near-infrared spectral ranges, may speed up the whitening process and potentially minimise structural changes to enamel when irradiation parameters are carefully managed. Despite these positive findings, current clinical evidence remains limited. Well-designed randomised controlled trials with standardised treatment protocols are essential to determine the best wavelengths, energy delivery settings, and safety limits for laser-assisted dental bleaching. Full article

Hair loss, particularly androgenetic alopecia (AGA) and alopecia areata (AA), is a prevalent condition with widespread psychosocial impact. Recently, low-level laser therapy (LLLT) has emerged as a promising non-invasive therapeutic alternative due to its bioregulatory effects and favorable safety profile compared to conventional pharmacological treatments. In this study, we employed fluorescence lifetime imaging microscopy (FLIM) to investigate the effects of red-light irradiation on hair follicle dynamics and the cutaneous microenvironment in a C57BL/6 mouse model. A hair regeneration model was established to evaluate the efficacy of 650 nm red-light irradiation (bandwidth ± 20 nm). Then, the skin tissue was stained with hematoxylin and eosin (H&E) and followed by FLIM analysis to provide a multidimensional assessment of tissue morphology and metabolic status. Results showed that red-light irradiation significantly increased hair follicle numbers and enhanced adenosine triphosphate (ATP) levels in the skin tissue. FLIM analysis further revealed prolonged fluorescence lifetime values across different epidermal and dermal layers in the irradiated group, indicating significant alterations in the skin metabolic microenvironment. Furthermore, phasor plot analysis enabled precise differentiation between hair follicles and their surrounding skin structures, highlighting FLIM’s high sensitivity and accuracy in evaluating hair growth. In conclusion, this study has provided novel imaging-based insights into the mechanisms of LLLT-induced hair regeneration, highlighting the potential of FLIM as a powerful tool for characterizing the cutaneous microenvironment and quantitatively evaluating phototherapeutic efficacy in future translational applications. Full article

Chroococcidiopsis sp. was isolated from the endolithic habitat of the Atacama Desert (northern Chile), one of the most challenging-to-life polyextreme environments on Earth. The photosynthetic machinery of microorganisms inhabiting this environment is supposed to be highly adapted to cope with the intense solar radiation of the area. Thus, PAR-red light ranging from 100 to 900 µmol photon·m⁻²·s⁻¹ has been investigated as a strategy to enhance culture productivity and stimulate the synthesis of bioactive molecules in Chroococcidiopsis sp. A control culture was maintained under white light at 100 µmol photon·m⁻²·s⁻¹. The results revealed that red light was utilized more efficiently than white light of similar irradiance, and its modulation enhanced both growth and photosynthetic activity of the cyanobacterium. Furthermore, Chroococcidiopsis sp. appeared to activate mechanisms to mitigate photooxidative stress produced by excess light energy. Specifically, increasing light irradiance induced photoacclimation responses, characterized by a decrease in chlorophyll content and a concomitant increase in carotenoid accumulation, likely aimed at reducing photon flux transduced to photosynthesis. Additionally, scytonemin synthesis was enhanced under high irradiances, contributing to dissipating excess light energy. Overall, this study demonstrates that modulation of red-light irradiance effectively improves the growth of Chroococcidiopsis sp. while promoting the accumulation of antioxidant compounds—primarily carotenoids and, to a lesser extent, scytonemin. Full article

Light exposure is a primary zeitgeber for the human circadian system and plays a key role in shaping sleep–wake patterns during adolescence, a period marked by biological sensitivity and social constraints. How the temporal organization and spectral composition of daily light exposure differ between weekdays and weekends remains poorly understood. Eighteen adolescents (15–17 years) were monitored for seven days using wrist actigraphy with integrated light sensors. Sleep parameters, nonparametric circadian rhythm indices, and time-resolved profiles of ambient and spectral (blue, green, and red) light exposure were analyzed. Repeated-measures ANOVA tested the effects of time of day and day type. Total sleep time and time in bed were longer on weekdays than on weekends (p < 0.05), while sleep latency and WASO did not differ. Circadian indices indicated preserved rhythmic organization. Light exposure showed a robust diurnal profile, with higher spectral irradiance on weekends (p < 0.001), especially in the morning and early afternoon. Significant time × day-type interactions were observed across all spectral bands (p < 0.001), indicating systematic reshaping of daily light profiles. Adolescents exhibit weekday–weekend differences in the temporal and spectral organization of light exposure, affecting the amplitude and shape of overall daily profiles. Full article

For the first time, red LED irradiation was applied at pilot scale in the table olive industry to evaluate its influence on Negrinha de Freixo cultivar natural fermentation. Physicochemical parameters, microbial dynamics, and sensory attributes were evaluated between 60 and 95 days, with two irradiation periods (60–70 and 85–95 days). Three conditions were examined: control-static, pumping-brine recirculation, and LED-brine recirculation + red light exposure. Color or texture was not affected. The lowest pH values were consistently observed in the LED-treated samples. Total phenolic compounds in olives showed a slight decrease from 60 to day 95; however, significant differences were only detected between the pumping treatment and the other two conditions. At the end of the first LED irradiation period, a growth of lactic acid bacteria and aerobic mesophilic bacteria was observed in the order of log 1.0 CFU/mL in the brine, and the yeast count (log 1.4 CFU/g) and LAB (log 1.2 CFU/g) in the olives relative to the control, while the second irradiation period did not show a significant effect. Sensory analysis revealed that LED- irradiated olives exhibited the highest hardness (5.6) values, whereas control samples presented the highest perception of putrid defect. Overall, the results demonstrate that red LED photostimulation may be promising for application in the table olive industry. Full article