Search Results (779)

The protozoan parasite Leishmania mexicana serves as a widely used model for studying trypanosomatid biology, yet the demand for stable, high-intensity fluorescent tools for precise subcellular protein localization remains unmet. In this study, we developed a versatile molecular toolbox by re-engineering the pLEXSY-hyg2.1 vector to express mNeonGreen (mNG), a next-generation fluorophore with superior brightness and photostability. Using a modular cloning strategy, we introduced a customized multiple cloning site (MCS) upstream of the mNG sequence to facilitate seamless N-terminal tagging of target proteins. The construct was integrated into the 18S rRNA locus via homologous recombination to ensure stable, constitutive expression. As a proof-of-concept, we fused a flagellar marker to the mNG reporter, resulting in a transgenic line exhibiting robust and specific subcellular fluorescence without compromising cellular fitness. Our results demonstrate that this integration-based system provides a highly efficient and stable platform for visualizing protein distribution within Leishmania. This tool significantly simplifies the generation of reporter strains and will facilitate high-resolution imaging studies of parasite organelle dynamics and functional genomics. Full article

In this study, a cellulose nanocrystal (CNC)-supported Ag–ZnO nanocomposite was synthesized via a hydrothermal route as a polymeric photocatalyst for efficient UV-A light-driven dye degradation. The renewable CNC framework provides abundant hydroxyl functional groups for nanoparticle anchoring, enhancing dispersion and interfacial charge transfer. Structural (XRD, FTIR, TEM, PL, and XPS) and thermal (TGA and DTG) analyses confirm successful incorporation of Ag nanoparticles and retention of CNC crystallinity. The composite exhibits a reduced optical bandgap (3.02 eV) and demonstrates superior photocatalytic activity, achieving 96% methylene blue (MB) degradation within 120 min. Enhanced performance is attributed to the synergistic effect of Ag-induced plasmonic excitation and CNC-facilitated charge migration, effectively suppressing ZnO photocorrosion. Moreover, the optimization of the parameters was conducted and found to be pH 7, a catalyst dose of 0.3 g L⁻¹, and an initial MB concentration of 10 ppm, which shows the best photocatalytic degradation reaction. The CNC/Ag–ZnO catalyst maintains 87% activity after five reuse cycles, showing good stability and reusability. The photostability of the CNC/Ag–ZnO catalyst was evaluated by ICP-MS, which measured Zn²⁺ concentration in the aqueous solution. Additionally, the degraded MB compounds were identified using GC-MS/MS analysis. This work highlights the potential of polymer-based biogenic supports for sustainable photocatalyst design and bridges polymer science with environmental remediation technology. Full article

The increasing prevalence of antimicrobial resistance, together with recurring infectious disease outbreaks, has intensified the need for alternative strategies to control microbial infections beyond conventional antibiotic therapies. Antimicrobial photodynamic therapy has emerged as a promising non-antibiotic approach in which light-activated photosensitising compounds generate reactive oxygen species that induce oxidative damage to microbial cells. Plant-derived photosensitisers have attracted increasing attention due to their structural diversity, biocompatibility, natural abundance, and potential for sustainability. Natural compounds such as curcumin, hypericin, chlorophyll derivatives, flavonoids, anthraquinones, and riboflavin exhibit favourable photochemical properties that enable efficient production of reactive oxygen species upon irradiation with visible light. Through radical- and singlet-oxygen-mediated photochemical pathways, these molecules exhibit broad-spectrum antimicrobial activity against bacteria, fungi, viruses, and biofilm-associated microorganisms. This review examines the photophysical properties and mechanisms of reactive oxygen species generation associated with plant-derived photosensitisers, together with key factors influencing their antimicrobial performance. Recent advances in nanocarrier-based delivery systems, dual-wavelength activation strategies, and synergistic combination therapies are also discussed for their potential to improve photostability, enhance reactive oxygen species generation, and increase microbial inactivation efficiency. Finally, current progress, challenges, and future research directions for advancing plant-derived photosensitisers in antimicrobial photodynamic therapy are discussed. Full article

The instability of pigments and non-quantitative indication limit the application of intelligent labels in food freshness monitoring. Natural anthocyanins face challenges including photodegradation and difficulty in quantifying shrimp freshness. To solve these problems, this study prepared a colorimetric intelligent label with UV-shielding and real-time monitoring functions. Carbon-coated nano-TiO₂ (C-TiO₂) was synthesized by the hydrothermal method and combined with blueberry anthocyanins (BAs) in an agarose (AG)/gellan gum (GG)/glycerol matrix. The label properties were characterized and a remaining shelf-life prediction model was established based on the correlation between label color difference (ΔE) and shrimp total volatile basic nitrogen (TVB-N). The results demonstrated that C-TiO₂ could enhance compatibility and color stability, and maintain mechanical properties. After 24 h of ultraviolet irradiation, the BA degradation rate was 98.4% in the GAB group and 62.8% in the GABT-0.05 group, representing a reduction of 35.6% compared to the former. This indicates that the addition of C-TiO₂ significantly enhanced photostability. The predictive model demonstrated an error below 10% at both 10 °C and 20 °C conditions, indicating its potential for shelf-life prediction applications. This dual-functional label provides a reliable method for visual and quantitative evaluation of shrimp freshness. Full article

Wounds, particularly chronic wounds, represent an increasing challenge for global health systems, affecting millions of people worldwide, and are often associated with persistent infections, biofilms, and multidrug-resistant microorganisms (MDRMs). In this context, the search for effective therapeutic alternatives has driven interest in photodynamic therapy (PDT), an approach in which light-excited photosensitizers promote the generation of reactive oxygen species (ROS) with antimicrobial and wound healing properties. Although first- and second-generation organic photosensitizers are widely used, they have significant limitations, including low aqueous solubility, self-aggregation, reduced photostability, and unsatisfactory ROS quantum yields. To overcome these drawbacks, various nanotechnology-based strategies have been explored. Among them, metallic nanoparticles stand out because they serve as carriers and exhibit intrinsic photosensitizing activity, high resistance to photobleaching, and remarkable extinction coefficients, which favor efficient singlet oxygen generation. Furthermore, metals such as gold and silver can enhance the performance of organic photosensitizers through a process known as metal-enhanced singlet oxygen generation, whereas others, such as copper, zinc, manganese, and magnesium, actively participate in biochemical events associated with the inflammatory and regenerative phases of wound healing. Considering these advances, this review compiles evidence published over the past five years regarding the use of metallic or metal-containing nanoparticles in PDT for acute and chronic wounds, with an emphasis on in vivo studies. In addition, we discuss the epidemiological and pathophysiological aspects of wounds and the intrinsic wound healing and antimicrobial properties of metallic compounds, thereby providing an integrated and up-to-date perspective. Full article

Recently, photoacoustic (PA) imaging has made a significant impact on biomedical imaging, providing detailed information on tissue structure and function by integrating optical and acoustic techniques. PA imaging can provide functional information at the cellular (e.g., oxygen saturation, hemoglobin concentration, metabolic rate) and molecular levels, owing to its substantial advantages over conventional imaging techniques. PA imaging is particularly useful for neuroimaging, cancer detection, and cardiovascular studies. Over the last decade, there has been a tremendous amount of research and development dedicated to nanomaterials that are ideal for PA imaging. Examples of nanomaterials include carbon-based and gold nanorods, both of which demonstrate greatly enhanced light absorption capabilities in the near-infrared range. Therefore, the properties of these materials make them perfect for achieving deep penetration into tissues. In addition, they exhibit biocompatibility, tunable optical properties, and enhance the acoustic signal for PA imaging, resulting in greater accuracy and precision in PA results. Researchers working in this area have focused on developing nanomaterials with fabrication capabilities, enabling real-time visualization of therapeutic events and enhancing light absorption. This review critically examines recent advances in nanomaterials for PA imaging, emphasizing strategies for signal enhancement and evaluating their impact on imaging performance, including imaging depth, photostability, and signal intensity, as well as their suitability for biomedical applications. Furthermore, complementary approaches for PA signal enhancement are discussed to provide a broader perspective and guide the selection and design of effective contrast agents for clinical and preclinical use. Full article

Photochromic molecules, capable of reversible isomerization under specific light irradiation, are pivotal for developing advanced photo-responsive materials. Azobenzene derivatives, in particular, are renowned for their significant conformational change, excellent reversibility, and high photostability. This study presents a novel cyclic diazo compound (CDTA) comprising two azobenzene units connected via flexible glycol chains. The photo-responsive behavior of CDTA doped into the liquid crystal 4-cyano-4′-octylbiphenyl (8CB) was systematically investigated. The composite exhibits a pronounced photo-induced phase transition from a liquid crystalline to an isotropic state under 365 nm UV irradiation, accompanied by a reversible change in light transmittance. The response kinetics were found to be highly dependent on temperature and dopant concentration. At 35 °C, the UV response time was accelerated to 6.8 s, attributed to the transition of the host 8CB from a smectic to a nematic phase. Furthermore, the composite demonstrated dual responsiveness: optical switching under UV light and electrical switching under an applied field in its nematic state. This work elucidates the interaction between molecular structure and photo-response in a liquid crystalline matrix, offering insights for designing next-generation smart windows and adaptive optical devices. Full article

All forms of neural communications, from cognition to emotion, are regulated by neurotransmitters, which are otherwise the chemical language of the brain. Precise detection of these neurotransmitters is essential for the perception of neurophysiology and diagnosis of neurodegenerative diseases as well. Among the existing techniques for the detection of these molecules, fluorescence sensing is evolving as a powerful approach in terms of high sensitivity, rapid response, and real-time visualization of the chemical events occurring in the neural system. In recent years, nanomaterials have transformed this field by integrating tunable optical properties, excellent photostability, and modifiable surface chemistry into biocompatible nanostructures. We summarize the recent advances of these architectures to show how the material type and dimensionality, as well as the surface functionality, play roles in sensing through the mechanisms of Förster resonance energy transfer (FRET), photoinduced electron transfer (PET), inner filter effect (IFE), and aggregation-induced emission (AIE). The discussion has also been extended to the correlation of fluorescence modulation with the selectivity and sensitivity in the mechanism-to-function relationship. The potential utility of such innovative technologies, including artificial intelligence, spectral deconvolution analysis via big data algorithms, and chip-integrated sensing, was explored as a means to enable real-time neurochemical detection. This converging area of nanotechnology and neuroscience leaves a mark not just in analytical accuracy, but also parallels human brain rhythms. Full article

Background/Objectives: The use of over-the-counter vitamin D₃ supplements has increased substantially in recent years. Compared with pharmaceuticals, dietary supplements are subject to less stringent regulatory oversight, raising concerns regarding labeling accuracy, consumer knowledge, and patient safety. This study aimed to assess public knowledge and preferences related to vitamin D₃ supplementation and to evaluate the content accuracy and short-term stability of commonly used products. Methods: A cross-sectional online survey containing 39 questions was conducted in Hungary between 1 May and 30 June 2024. Based on survey responses, the most frequently used vitamin D₃ supplements (five soft gel capsules and four tablets) were selected for laboratory analysis. Vitamin D₃ content was quantified using a validated high-performance liquid chromatography (HPLC) method with UV detection. Soft gel capsules were additionally exposed to natural daylight for one month to assess short-term photostability. Results: In total, 367 participants (mean age 31.0 ± 12.5 years) completed the survey, and only 3.5% answered correctly all knowledge-based questions. Six commonly reported supplement brands accounted for approximately 90% of responses. Measured vitamin D₃ content remained within the tolerance limit (−20% to +50%). Following sunlight exposure, three of four capsule products showed no substantial vitamin D₃ loss, while one exhibited a 14.7% decrease. Conclusions: Most analyzed vitamin D₃ supplements complied with labeled content claims, but substantial knowledge gaps were identified that may affect patient safety. The validated HPLC method supports pharmacovigilance-oriented quality monitoring of vitamin D₃ supplements and underscores the need for improved professional counseling. Full article

Copper(I) clusters have attracted significant interest due to their ultrasmall size, excellent photostability, large Stokes shift, and long emission lifetime. However, research on their structure–property relationship remains limited. In this study, we synthesized and comprehensively characterized a series of trinuclear copper(I) clusters, [Cu₃(dppm)₃(C≡CC₆H₄X)₂]PF₆ [Cu₃-X, X = F, Cl, Br, and I, dppm = bis(diphenylphosphino)methane], in order to investigate the effect of ligands containing heavy atoms on photoluminescence. All clusters have the same triangular metal core and similar distribution of ligands, with the only difference being the substituent on the phenyl ring of the arylacetylene ligand. Owing to the heavy-atom effect, a notable Stokes shift was observed in the emission spectra of the clusters. Specifically, the emission peak of Cu₃-I reached 564 nm, representing a 73 nm red shift compared to that of Cu₃-F. Furthermore, Cu₃-Br showed an absolute photoluminescence quantum yield of 15.24% and a lifetime of 114.56 μs, corresponding to 3.3-fold and 3.7-fold increases over the values for Cu₃-F. This study provides novel insights into the heavy-atom effect of surface ligands on the luminescence of copper(I) clusters and offers a robust platform for probing their structure–property relationships. Full article

Dual-emission photoluminescence (PL) nanoprobes provide improved analytical performance to develop a reliable and sensitive sensing platform for quantifying chloramphenicol in pharmaceutical samples, thereby ensuring therapeutic efficacy and patient safety. In this work, a dual-emission PL sensing platform combining carbon dots (CDs) and AgInS₂ quantum dots (QDs) capped with mercaptopropionic acid (MPA) was developed for the quantitative determination of chloramphenicol, resorting to chemometric methods for data analysis. CDs, CdTe QDs, and AgInS₂ QDs were synthesized and individually evaluated considering their photostability, PL response and kinetics of their interaction with the antibiotic. After this, two dual-emission probes, CDs/MPA-CdTe and CDs/MPA-AgInS₂, were prepared and assessed based on the complementarity of their individual emission features. The obtained kinetic PL dataset was processed using unfolded partial least squares (U-PLS) in order to explore the multidimensional information of the dual-emission systems and to evaluate the performance of both sensing platforms. CDs/MPA-AgInS₂ probe was demonstrated to be the most efficient sensing platform due to its better compromise between sensitivity and photostability, as well as its cadmium-free composition, allowing the implementation of a more environmentally friendly analytical methodology. The optimization of the U-PLS models involved the assessment of the kinetic acquisition time and different spectral regions. The results showed that reliable, sensitive and efficient quantification could be achieved within the first 5 min of interaction and using the full emission spectrum of the sensing probe. Additionally, different interaction mechanisms were observed for each nanomaterial in the combined probe, being static for the CDs/chloramphenicol interaction and dynamic for MPA-AgInS₂/chloramphenicol interaction, which supports the synergetic behavior of the combined probe. The proposed methodology was effectively applied to commercial pharmaceutical formulations, yielding accurate results with good figures of merit. Therefore, this approach can be used as a relevant alternative to existing methodologies for a rapid, robust, and environmentally friendly method for chloramphenicol quantification. Full article

Cannabinoids are of considerable current interest for use in pharmaceutical and non-medical consumer products. While there have been significant efforts to understand their chemical stability under ambient conditions, only sparse attention has been paid to characterising their photostability. Here, we present UVA (365 nm) and UVB (280 nm) photolysis measurements of eight representative cannabinoids, including natural compounds (THC, CBD, THCA, CBDA), metabolites (THC-COOH, THC-OH), and synthetic analogues (JWH-018, MDMB-FUBINACA). Measurements were performed using a novel online-electrospray mass spectrometry (MS) approach, where online photolysis of cannabinoid solutions was conducted with laser light-emitting diodes. MS detection was used to monitor precursor compound decay and photoproduct formation. Complementary results obtained via UV–Vis spectroscopy of photolysed cannabinoid solutions are also presented. For THC, CBD, THC-COOH, THC-OH, THCA and CBDA, significant photodegradation was observed with 280 nm photolysis, both through the appearance of photoproducts detected by MS and via time-dependent changes in the solution UV–Vis absorption profiles. In contrast, the synthetic cannabinoids (JWH-018 and MDMB-FUBINACA) showed negligible degradation with UVB photolysis, consistent with their relatively low absorbance propensity through the mid-UV region. No significant photodegradation was observed for UVA (365 nm) photolysis of any of the cannabinoids. The results presented here constitute the first directly comparable set of photolysis measurements for key phytocannabinoids. Full article

In this work, we synthesized blue-fluorescent nitrogen-doped carbon quantum dots (N-CQDs) via a facile, economical, and environmentally friendly one-pot synthesis, using citric acid as the carbon source and polyethyleneimine (PEI) as the nitrogen dopant. The as-prepared N-CQDs exhibited uniform size distribution, with an average diameter of approximately 3 nm and a quantum yield of up to 23.6%. Based on the mechanism of HClO-triggered static fluorescence quenching and oxidation of surface amine groups on the N-CQDs, we established a quantitative detection platform for hypochlorous acid (HClO). The proposed method demonstrated a linear response over the concentration range of 0–40 μmol/L, with a detection limit as low as 0.17 μmol/L. It also featured a rapid response time (within 2 min), high selectivity, and strong anti-interference capability against various common species, including Cl⁻, H₂O₂, NO₂⁻, NO₃⁻, TBHP, TBO•, Br⁻, I⁻, S²⁻, F⁻, O²⁻ and HO•. Furthermore, the probe was successfully applied to detect HClO in real-world samples such as river water and beer. Owing to its outstanding photostability and low toxicity, it proved highly effective for monitoring intracellular HClO in living cells. Full article

Organic luminescent radicals with through-space charge-transfer (TSCT) excited states are attractive for optoelectronic applications, yet donor-dependent structure–property relationships remain underexplored. Here we report a new spirofluorene-bridged TSCT radical, PID-FR-TTM, employing 1-phenyl-1H-indole (PID) as the donor. Single-crystal X-ray diffraction confirms a carbon-centered TTM radical and a less bulky, more planar five-membered N-heterocycle in the donor region. PID-FR-TTM shows TSCT-type absorption and an emission at 609 nm with a photoluminescence quantum yield (PLQY) of 23.1% and a 90.1 ns emission lifetime in cyclohexane. Calculations indicate a TSCT-dominated excited state and a pronounced singly occupied molecular orbital–highest occupied molecular orbital (SOMO–HOMO) inversion. Notably, PID-FR-TTM exhibits markedly improved stability, including high decomposition temperatures (≈340 °C), excellent electrochemical stability, and enhanced photostability. These results provide donor-structure insights for designing high-performance TSCT radical emitters. Full article

Constructing a donor–acceptor (D–A) architecture in luminescent radicals is an effective strategy for enhancing luminescent properties. However, further structural modification of the radical core through the simple substitutions in the framework of D–A radicals remains relatively underexplored. Herein, we synthesized two radical derivatives TTM-Mes-Cz-Mz and TTM-Mes-Dpa-Mz through modification of the TTM unit of TTM-Cz and TTM-Dpa with imidazole and mesitylene groups. These radical derivatives exhibited high photoluminescence quantum efficiency (PLQE) (80% for TTM-Mes-Cz-Mz and 39% for TTM-Mes-Dpa-Mz) and photostability. The radical units were further covalently grafted onto the polymer chains to synthesize ionic radical polymers LT-Cz and LT-Dpa. LT-Cz and LT-Dpa showed PLQE of 39% and 29% in a solid state, respectively. Furthermore, the polymers exhibited solvent-responsive luminescence with dichloromethane and tetrahydrofuran. A significant redshift in emission wavelength and decrease in emission intensity were observed. The polymers could return to their initial state with solvent evaporation. This work advances the exploration of the role of simple substituent modifications in D–A radical systems, thereby enabling highly efficient luminescence in both small-molecule radicals and radical polymers. Full article