Search Results (1,266)

Background/Objectives: This study reports the synthesis of TiO₂ nanoparticles, their functionalization with folic acid (FA), and the subsequent loading with zinc phthalocyanine (ZnPc) to develop photosensitizers for photodynamic therapy (PDT) targeting glioma cells. Methods: TiO₂, TiO₂-FA, and TiO₂-FA-ZnPc nanoparticles were synthesized via a sol–gel process involving the hydrolysis and condensation of titanium (IV) isopropoxide. FA and ZnPc were incorporated in vitro during the synthesis. The resulting materials were characterized by transmission and scanning electron microscopy (TEM and SEM), X-ray diffraction (XRD), Raman and UV–Vis spectroscopy, thermogravimetric analysis (TGA), and nitrogen adsorption–desorption measurements. Reactive oxygen species (ROS) generation was evaluated in vitro using the 1,3-diphenylisobenzofuran (DPBF) probe. A 40 ppm solution of each TiO₂ system was irradiated with UV light, and the degradation of DPBF was monitored. Biological assays were conducted to assess the viability of human glioblastoma cells (LN18 and U251) incubated with the TiO₂-based materials, with and without UV exposure. Human fibroblast cells (BJ) were used to evaluate biocompatibility. Results: All TiO₂-based materials retained key characteristics, including high surface area (~600–700 m²/g), mesoporous structure (pore diameter ~4–5 nm), mixed anatase–amorphous morphology, and a bandgap of approximately 3.46 eV. The UV–Vis spectrum of TiO₂-FA-ZnPc displayed additional absorption bands in the visible region (600–700 nm), consistent with ZnPc incorporation. Upon UV irradiation, the DPBF absorbance at 410 nm decreased over time, indicating ROS generation and resulting in complete degradation within 10 min (TiO₂), 12 min (TiO₂-FA), and 14 min (TiO₂-FA-ZnPc). BJ cells exhibited good biocompatibility at all concentrations. LN18 and U251 cells showed no cytotoxicity below 100 μg/mL unless exposed to UV light. Conclusions: The synthesized TiO₂-based systems demonstrate good biocompatibility and significant phototoxicity under UV irradiation, highlighting their strong potential for application in photodynamic therapy. Full article

The present reported work deals with the preparation of an energy-efficient smart window based on liquid crystal (LC) using a polymer-dispersed liquid crystal (PDLC) technique. The smart window was prepared using an LC–polymer composite by mixing photopolymer NOA-71 into nematic liquid crystal (NLC) 4-cyano-4’-pentylbiphenyl (5CB). The liquid crystal cell was prepared, the LC–polymer composite was filled inside the cell, and voltage was applied after the exposure of ultraviolet (UV) light. Textural analysis was carried out, and microscope images were taken out with the variation in voltage. Optical measurements were also performed for the smart window based on the PDLC system. Threshold voltage and saturation voltages were measured to carry out the operating voltage analysis. Transmittance was measured as a function of wavelength at different voltages. An absorbance study was also performed, varying the voltage and wavelength. The change in the power of the laser beam passing through the prepared smart window as a function of voltage was also investigated. The working of a prepared smart window using liquid crystal and a photopolymer composite is also demonstrated in opaque and transparent states in the absence and presence of voltage. The output of the present investigation into a PDLC-based smart window can be useful in the applications of adaptive or light shutter devices and in aerospace technology, as it shows the dual nature of opaque and transparent states in the absence and presence of electric field. Full article

Green synthesis of copper oxide (CuO) nanoparticles offers a sustainable alternative to conventional chemical methods that often involve toxic reagents and harsh conditions. This study investigates the use of Tithonia diversifolia, an invasive species in Sri Lanka, as a bioreductant for the eco-friendly fabrication of CuO nanoparticles. Using copper sulfate (CuSO₄·5H₂O) as a precursor, eight treatments were conducted by varying precursor concentration, temperature, and reaction time to determine optimal conditions. A visible color change in the reaction mixture initially indicated nanoparticle formation. Among all the conditions, treatment T4 (5 mM CuSO₄, 80 °C, 2 h) yielded the most favorable results in terms of stability, morphology, and crystallinity. UV-Vis spectroscopic analysis confirmed the synthesis, with absorbance peaks between 265 and 285 nm. FTIR analysis revealed organic functional groups and characteristic metal–oxygen vibrations in the fingerprint region (500–650 cm⁻¹), confirming formation. SEM imaging showed that particles were mainly spherical to polygonal, averaging 125–150 nm. However, dynamic light scattering showed larger diameters (~240 nm) due to surface capping agents. Zeta potential values ranged from −16.0 to −28.0 mV, indicating stability. XRD data revealed partial crystallinity with CuO-specific peaks. These findings support the potential of T. diversifolia in green nanoparticle synthesis, suggesting a low-cost, eco-conscious strategy for future applications. Full article

Commercially available bismuth subcarbonate (Bi₂O₂CO₃) was treated with nitric acid and the surfactant cetyltrimethylammonium bromide. The treated catalysts exhibited enhanced photocatalytic activity compared to pure Bi₂O₂CO₃ in the decolorization of rhodamine B (RhB) under visible light irradiation. The absorbance at 554 nm gradually decreased over time and disappeared completely within 80 min. The crystal structure, morphology, and optical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The improved photocatalytic activity of the treated catalysts was attributed to partial carbonate removal and the formation of Bi⁵⁺ species. Scavenger experiments indicated that superoxide radicals (·O₂⁻) and photogenerated holes (h⁺) played significant roles in the photocatalytic decolorization of RhB. Full article

The article presents the first method based on high-performance liquid chromatography and ultraviolet detection (HPLC-UV) for the determination of timonacic (thioproline, 1,3-thiazolidine-4-carboxylic acid, tPro) in pharmaceutical tablets and face care products (creams, sera, foundations, suncreams). Sample preparation primarily involves solid-liquid extraction (SLE) of tPro with 0.2 mol/L phosphate buffer pH 6, derivatization with 0.25 mol/L 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT), followed by polytetrafluoroethylene (PTFE) membrane filtration. The chromatographic separation of the stable UV-absorbing 2-S-quinolinium derivative is achieved within 14 min at 25 °C on a Zorbax SB-C18 (150 × 4.6 mm, 5 µm) column using gradient elution. The eluent consists of 0.1 mol/L trichloroacetic acid (TCA), pH 1.7, in a mixture with acetonitrile (ACN) delivered at a flow rate of 1 mL/min. The analyte is quantified by monitoring at 348 nm. The assay linearity was observed within 0.5–125 μmol/L. The limit of quantification (LOQ) was found to be 0.5 μmol/L. The accuracy ranged from 93.22% to 104.31% and 97.38% to 103.48%, while precision varied from 0.30% to 11.23% and 1.13% to 9.64% for intra- and inter-assay measurements, respectively. The method was successfully applied to commercially available on the Polish market pharmaceutical and cosmetic products. Full article

The intense demand for alternatives to conventional plastics has increasingly motivated the development of biodegradable packaging. However, the ecological impact of these materials when discarded in natural settings has not yet been evaluated. Therefore, this study investigated the effects of films based on chia mucilage in different aquatic environments. The solubilization time varied according to water type, ranging from 40 min in ultrapure, deionized, and distilled water to 230 min in saline water. After solubilization, all water samples exhibited increased turbidity (from 1.04 to 15.73 NTU in deionized water) and apparent color (from 0 to 44 PCU in deionized water) as well as pH variations depending on ionic strength. Deionized water also showed the highest viscosity increase (>350 Pa·s at 1 s⁻¹). UV–Vis spectra revealed a moderate rise in absorbance between 236 and 260 nm, indicating organic compound release. Regarding phytotoxicity, the solubilized films had no toxic effect and promoted a biostimulating effect on root elongation, with Relative Germination Index values exceeding 140% in most samples. These results reinforce the potential of chia-based films for controlled disposal, particularly in low-salinity environments, while highlighting the importance of evaluating post-solubilization interactions with aquatic systems. Full article

This study investigates the effect of precursor pH (1.3, 2, 4, 6, 8, and 10) on the synthesis of gold nanoparticles (AuNPs) via a green synthesis approach using an aqueous extract of green tea (Camellia sinensis) leaves. The formation of AuNPs was monitored using UV-vis spectrophotometry and confirmed using transmission electron microscopy (TEM). The results confirmed that the morphology and size of the AuNPs are strongly dependent on the pH of the reaction medium. Based on spectral features, the color of the colloids, and TEM analysis, the synthesized samples were classified into three groups. The first (pH 8 and 10) contained predominantly spherical nanoparticles with an average diameter of ~18 nm, the second (pH 1.3 and 2) contained different shaped nanoparticles (20–250 nm in diameter), and the third (pH 4 and 6) contained flower-like nanostructures with a mean diameter of ~60 nm. UV-vis analysis revealed good stability of all AuNP colloids, except at pH 1.3, where a significant decrease in absorbance intensity over time was observed. These findings confirm that tuning the precursor pH allows for controlled manipulation of nanoparticle morphology and stability in green synthesis systems. Full article

Calcipotriol, a synthetic vitamin D₃ analogue widely used in psoriasis treatment, requires a detailed stability assessment due to its topical application and potential exposure to UV radiation. As a drug applied directly to the skin, calcipotriol is particularly susceptible to photodegradation, which may affect its therapeutic efficacy and safety profile. The present study focuses on the analysis of calcipotriol photostability. An advanced UHPLC/MS^E method was employed for the precise determination of calcipotriol and its degradation products. Particular attention was given to the effects of commonly used organic UV filters—approved for use in cosmetic products in both Europe and the USA (benzophenone-3, dioxybenzone, meradimate, sulisobenzone, homosalate, and avobenzone)—on the stability of calcipotriol. Unexpected degradation of calcipotriol was observed in the presence of sulisobenzone. Importantly, this effect was consistently detected in methanolic solution and in the pharmaceutical formulation containing calcipotriol and betamethasone, which is particularly significant from a practical perspective. This finding underscores the necessity of evaluating photostability under real-life conditions, as cosmetic ingredients, when co-applied with topical drugs on the skin, may substantially influence the stability profile of the pharmaceutical active ingredient. The research resulted in the first-time characterization of four degradation products of calcipotriol. The degradation process was found to primarily affect the E-4-cyclopropyl-4-hydroxy-1-methylbut-2-en-1-yl moiety, causing its isomerization to the Z isomer and the formation of diastereomers with either the R or S configuration. Computational analyses using the OSIRIS Property Explorer indicated that none of the five degradation products exhibit a toxicity effect, whereas molecular docking studies suggested possible binding of two of the five degradation products of calcipotriol with the VDR. Full article

Fully printable carbon-based multiporous layered electrode perovskite solar cells (MPLE−PSCs) are close to being commercialized due to their excellent stability, their ability to easily be scaled up, and their amenability to mass production via non-vacuum fabrication processes. To improve their efficiency, it is important that detailed studies of the morphologies of mesoporous electrodes be carried out. In this study, we prepared five types of ZrO₂ spacer layers for MPLE−PSCs, and the morphology of ZrO₂ and device performance were evaluated using a scanning electron microscope, nitrogen adsorption/desorption measurements, electrode resistance measurements, UV-visible light reflectance measurements, and current density–voltage measurements. The results reveal that the adequate specific surface area and pore size distribution of mesoporous ZrO₂ provided high insulation ability when used as spacers between electrodes and light absorbance, resulting in a 10.92% photoelectric conversion efficiency with a 23.22 mA cm⁻² short-circuit current density. This information can serve as a guideline for designing morphologies useful for producing high-efficiency devices. Full article

The aim of this study was to elucidate all the degradation byproducts (DBPs) of bemotrizinol (BEMT) that are associated with sodium hypochlorite treatment. BEMT is a UV filter that is found not only in many personal care products, such as sunscreen and cosmetics, but also as an additive in plastics or clothing to protect them from damage that results from absorbed radiation. BEMT has been detected in wastewater, surface water, and some lake sediments, in quantities from a few ng/L to hundreds of ng/L, to such an extent that, today, it is considered an emerging pollutant. In this study, the UV filter was subjected to oxidation with sodium hypochlorite, which is an oxidant at the base of the disinfection process that is used in most wastewater treatment plants or in swimming pools. Using different chromatographic methods (CC, TLC, HPLC, and GC), the resulting DBP mixture was separated into its main components, which were then identified using one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. Nineteen DBPs were isolated, and a plausible reaction mechanism was proposed to explain how they were obtained. Full article

Fungal melanin plays a vital role in the survival, reproduction, infection, and environmental adaptation of plant pathogenic fungi. To develop innovative strategies for managing plant fungal diseases, comprehensive investigations into melanin are imperative. Such research is fundamental to elucidating the mechanistic basis of fungal pathogenesis and holds promise for the design of targeted interventions against melanin-mediated virulence determinants. This review systematically elaborates on the classification of fungal melanin in plant pathogens, provides a detailed analysis of the biosynthetic processes of 3,4-dihydroxyphenylalanine (DOPA) and 1,8-dihydroxynaphthalene melanin (DHN melanins), and reveals the catalytic functions and regulatory mechanisms of key enzymes within these pathways. Melanin modulates fungal virulence by influencing appressorial integrity and turgor pressure formation, thereby participating in the host infection process and the formation of overwintering sclerotia. Melanin provides stress resistance by protecting against extreme environmental factors, including UV radiation and high temperatures. It also has the capacity to absorb heavy metals, which increases pathogen survival under adverse conditions. Furthermore, the review also explores the mechanisms of action of melanin inhibitors that target plant pathogenic fungi, providing a theoretical foundation for developing efficient and environmentally friendly antifungal medications. The complex biosynthesis pathways and diverse biological functions of fungal melanin highlight its significant theoretical and practical importance for elucidating pathogenic mechanisms and formulating scientific control strategies. Full article

Dye-sensitized solar cells (DSSCs) are promising alternatives for power generation due to their environmental friendliness, cost effectiveness, and strong performance under diffused light. Conversely, their low spectral response in the ultraviolet (UV) region significantly obliterates their overall performance. The so-called luminescent down-shifting (LDS) presents a practical solution by converting high-energy UV photons into visible light that can be efficiently absorbed by sensitizer dyes. Herein, a conventional solid-state technique was applied for the synthesis of an LDS, europium (II)-doped barium orthosilicate (BaSiO₃:Eu²⁺) material. The material exhibited strong UV absorption, with prominent peaks near 400 nm and within the 200–300 nm range, despite a weaker response in the visible region. The estimated optical bandgap was 3.47 eV, making it well-suited for UV absorbers. Analysis of the energy transfer mechanism from the LDS material to the N719 dye sensitizer depicted a strong spectral overlap of $2\times {10}^{10}{\mathrm{M}}^{-1}{\mathrm{c}\mathrm{m}}^{-1}{\mathrm{n}\mathrm{m}}^4$, suggesting efficient energy transfer from the donor to the acceptor. The estimated Förster distance was approximately $6.83\mathrm{n}\mathrm{m}$, which matches the absorption profile of the dye-sensitizer. Our findings demonstrate the potential of BaSiO₃:Eu²⁺ as an effective LDS material for enhancing UV light absorption and improving DSSC performance through increased spectral utilization and reduced UV-induced degradation. Full article

Prolonged ultraviolet (UV) exposure accelerates aging and degradation, while conventional constant-intensity UV simulations do not reflect the variable nature of outdoor radiation. Aging duration and film thickness are both key factors affecting Rubber-Modified Asphalt (RMA), but how their combination influences RMA remains unclear. To address this limitation, this research employed accelerated aging experiments under variable-intensity UV radiation to investigate the performance and aging mechanism of RMA across different aging durations and asphalt film thicknesses. Rheological properties were analyzed through rheological tests, and the UV aging mechanisms of RMA were revealed using FTIR and SEM. The results revealed that crumb rubber improved RMA’s UV aging resistance, including high-temperature performance, fatigue life, and low-temperature cracking resistance. Aging effects were more influenced in RMA with thinner films under prolonged UV exposure. After nine cycles of ultraviolet aging, the rutting resistance, elastic recovery, fatigue life, and low-temperature cracking resistance of RMA with a 1 mm film thickness were 1.33, 1.11, 0.54, and 0.67 times, respectively, those of RMA with a 2 mm film thickness subjected to three UV aging cycles. RMA demonstrated comparable high-temperature performance and elastic recovery under UV aging conditions corresponding to a 1.5 mm film thickness aged for three cycles and a 2.0 mm film thickness aged for six cycles, as well as a 1.0 mm film thickness aged for six cycles and a 1.5 mm film thickness aged for nine cycles. FTIR showed that the increased activity of C=C and C-H under photo-oxidative aging caused a greater impact on the carbonyl groups than the sulfoxide groups. Under high-intensity UV radiation, RMA with thinner films exhibited greater rubber powder detachment, increased surface oxidation, and a substantial widening of cracks. The rubber powder absorbed UV radiation, enhancing the stability of RMA. The maximum crack width of the 1 mm NA was twice that of RMA. These provided insight into the microstructural pattern of cracking resistance degradation caused by aging. This research provides theoretical support for the optimization of the anti-aging performance of RMA. Full article

The study of the effects of 2.45 GHz electromagnetic fields on the health and safety of people and organisms as a whole is essential due to their widespread use in everyday life. It is known that they can cause thermal and non-thermal effects—at the molecular, cellular and organismal level. Yeast suspensions were treated with 2.45 GHz microwave radiation in the near-field of antenna at two distances (2 and 4 cm) and two time periods (20 and 60 min)—setups resembling the use of mobile devices. The release of UV-absorbing substances from the cells was studied as an indicator of membrane permeabilization, total intracellular antioxidant activity and reduced glutathione were determined, and a comet assay for damage to the DNA was performed. A correlation between reduced antioxidants and increased membrane permeability during EMF treatment was observed at a distance of 2 cm for 20 min, suggesting the presence of oxidative stress, while a similar effect was not observed with conventional heating. Slightly increased membrane permeability was observed after irradiation for 60 min at a distance of 4 cm, but this was not related to the antioxidant status of the cells. A trend towards increased DNA damage was observed under both conditions. Full article

Melanin-like nanoparticles (NPs) exhibit a remarkable ability to absorb light across a wide range of wavelengths, from the ultraviolet (UV) to the near-infrared (NIR) spectrum. This characteristic enables them to serve as effective photothermal agents (PTAs). Upon irradiation, especially within the NIR window, a region where biological tissues are highly transparent, these NPs efficiently convert light energy into heat. This phenomenon, known as the photothermal effect, leads to localized temperature increases. The resulting heat can be strategically employed to induce selective cell death in photothermal therapy (PTT) or to enhance the release of therapeutic agents directly from the NPs. The inherent versatility of melanin-like NPs, stemming from their synthesis methods and the presence of various functional groups, allows for straightforward loading with drugs or other bioactive molecules. Consequently, they are attractive tools for photothermally activated release. This review paper thoroughly examines and critically discusses the latest applications of melanin-like NPs in photothermally controlled release. We dedicate a specific section to general mechanisms and approaches, and this paper concludes with an analysis of critical challenges and prospective future developments. Full article