Search Results (3,441)

G-quadruplexes (G4s) are noncanonical nucleic acid structures involved in gene regulation and genome stability. Among them, the telomeric repeat-containing RNA (TERRA) forms biologically relevant RNA G4s (rG4s) that participate in telomere maintenance and genome stability. Although many ligands targeting DNA G4s have been reported, the recognition and modulation of RNA G4 topologies remain less explored. In this work, we investigated the interaction between TERRA and the spermine-functionalized Zn(II) porphyrin, ZnTCPPSpm4, using UV–vis absorption, fluorescence, resonance light scattering (RLS), and circular dichroism (CD) spectroscopy. In K⁺, where TERRA adopts a parallel G4 conformation, ZnTCPPSpm4 binds through a stepwise mechanism involving external end-stacking, forming discrete supramolecular complexes without altering the native topology. In contrast, under Na⁺ conditions, ZnTCPPSpm4 induces a gradual conformational rearrangement of TERRA from the antiparallel to a parallel-like G4 topology. A CD melting study showed that ZnTCPPSpm4 stabilizes the parallel RNA G4, while slightly destabilizing the antiparallel topology. Overall, our results demonstrate that ZnTCPPSpm4 is not a simple G4 binder, but a topology-selective ligand capable of remodeling TERRA G4 structures, highlighting the potential of metalloporphyrins as RNA G4-targeting scaffolds. Full article

The precise determination of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels is critical for understanding the photophysical and photochemical properties of carbon dots (C-dots), which directly govern their performance in optoelectronic, catalytic, and sensing applications. However, the lack of distinct redox peaks in cyclic voltammetry (CV) curves of C-dots poses a major challenge to conventional energy level calculation methods. Herein, we propose a novel strategy to calculate the HOMO–LUMO energy levels of C-dots by combining electron transfer (ET) kinetics with Marcus theory. A series of quinones (electron acceptors, EAs) and ferrocene derivatives (electron donors, EDs) were employed to quench the fluorescence of C-dots, and the ET rate constants (K) were derived from fluorescence lifetime measurements. The CV curves of EAs and EDs provided their respective oxidation and reduction potentials, which were used as reference energy levels. The UV–Vis absorption spectra confirmed that the fluorescence quenching mechanism was dominated by ET rather than energy transfer. Based on Marcus theory, the free energy change (ΔG) of ET reactions was correlated with K, and the HOMO and LUMO energy levels of C-dots were calculated to be −1.84 V (vs. SCE) and +1.60 V (vs. SCE), respectively. This study not only provides a reliable method for determining the energy levels of C-dots without distinct redox peaks but also deepens the understanding of ET mechanisms between C-dots and small molecules. The proposed strategy is expected to be extended to other fluorescent nanomaterials with similar CV limitations. Full article

Magneto-fluorescent carbon quantum dots (CQDs) promise compact, dual-readout nanomaterials; however, achieving pronounced photoluminescence alongside magnetic functionality in a simple, scalable formulation remains difficult, especially for emerging doped CQDs. Here, we report Fe-doped carbon quantum dots (Fe-CQDs) as an emerging quantum-dot platform that integrates fluorescence with magnetic-resonance (MR) relaxometry within a single ultrasmall, carbonaceous nanostructure. To enable this, Fe-CQDs are prepared through a straightforward two-step, low-temperature route that uses a magnetic deep eutectic solvent precursor followed by mild carbonization in air at atmospheric pressure. Under UV excitation, the Fe-CQDs display bright blue emission centered at 439 nm, and their optical behavior is characterized by UV-Vis absorption, photoluminescence spectroscopy, and fluorescence microscopy. Meanwhile, dynamic light scattering indicates a narrowly distributed nanoscale hydrodynamic diameter, and X-ray diffraction together with FT-IR supports a carbonaceous framework enriched with oxygenated surface functionalities, consistent with aqueous dispersibility and environmentally responsive photophysics in water, while XPS supports Fe incorporation in an Fe(III)-dominated chemical environment. Importantly, Fe incorporation enables intrinsic MR relaxometric readout, establishing an intrinsic fluorescence/MR dual modality. As a proof-of-concept, Fe-CQDs were tested with a representative per- and polyfluoroalkyl substance (PFAS), showing parallel fluorescence and MR response trends at ppm levels in natural water matrices from Millerton Lake with Stern–Volmer analysis and a NaCl-based ionic strength control. Overall, these results position Fe-CQDs as a versatile magneto-fluorescent nanomaterial for dual-readout screening workflows and motivate future surface engineering and dopant tuning to improve selectivity and expand toward multi-modal readouts. Full article

The environmental persistence of β-lactam antibiotics represents a growing ecological concern, requiring materials capable of combined adsorption and catalytic degradation. Herein, pure ZnS and 1% Fe-doped ZnS nanoparticles were synthesized via microwave-assisted treatment and evaluated for the removal of ceftaroline fosamil from aqueous media. Transmission electron microscopy revealed quasi-spherical nanoparticles below 10 nm, while selected area electron diffraction confirmed a face-centered cubic structure retained after Fe incorporation. UV-Vis spectroscopy showed similar absorption edges (~316 nm), indicating negligible band-gap variation, whereas photoluminescence analysis demonstrated strong emission quenching in Fe-ZnS, indicating suppressed electron–hole recombination. Point-of-zero charge measurements (pH_PZC ≈ 4.6 for ZnS; 4.5 for Fe-ZnS) indicated negatively charged surfaces under circumneutral conditions, influencing interfacial interactions with the antibiotic. Adsorption experiments followed the Langmuir isotherm model, with Fe-ZnS exhibiting a higher maximum adsorption capacity (156 mg g⁻¹) compared to ZnS (115 mg g⁻¹). Under UV irradiation (302 nm), Fe-ZnS achieved near-complete degradation at a catalyst loading of 500 ppm. Liquid chromatography–mass spectrometry analysis revealed the transformation of ceftaroline fosamil (m/z 685.01) into ceftaroline (m/z 605.05) via phosphate group loss, followed by the formation of intermediate fragments at m/z 492.08 and 308.03, associated with cleavage of the thiadiazol-amine moiety and subsequent opening of the cephalosporin ring. After extended irradiation, these intermediates diminished, and a fragment at m/z 356.01 was detected, suggesting further breakdown through thioether bond cleavage. These results support a degradation pathway involving sequential dephosphorylation and fragmentation of the cephalosporin core. Overall, the enhanced performance of Fe-ZnS arises from the synergistic interplay between surface charge characteristics and dopant-modulated charge carrier dynamics, highlighting its potential for antibiotic remediation in aquatic environments. Full article

Thirty 2-methyl-quinazolinone fussed hydroxamic acids (3-OH) and their 3-OEt and 3-OBn derivatives were evaluated for their affinity towards calf-thymus (CT) DNA using UV-vis absorption, viscosity and fluorescence spectroscopy. DNA photocleavage activity was assessed by incubating the compounds with plasmid DNA followed by UV-A and visible light irradiation, which enabled identification of the most potent derivatives active at concentrations of 100 nΜ and 10 μΜ, respectively. Mechanistic studies on the most active compounds indicated the formation of oxygen radical species and a decrease in efficiency under argon. Measurements of singlet oxygen release verified these findings. Molecular docking studies provided further insight into the interactions between the compounds and DNA. UV-A irradiation of the most potent DNA photocleavers in three cell lines, two malignant melanoma lines (A375 and COLO-800) and the immortalized keratinocyte line HaCaT, identified three derivatives that, at a concentration up to 10 μΜ, reduced cell viability by approximately 50%. Taken together, these results indicate that these 2-methylquinazolinone-based hydroxamic acid derivatives are promising candidates for the development of photodynamic therapy agents. Full article

In this study, a non-typical luminescent organosilicone was synthesized through a click reaction and used as a cross-linker to cure hydroxyl-terminated dimethylsilicone oil at room temperature via the sol–gel process, followed by application as a coating on a glass surface. This organosilicone film functions effectively as a luminescent down-shifting (LDS) material. Additionally, the presence of methyl groups and voids in the structure imparts a low refractive index, allowing it to serve as an anti-reflective (AR) layer. Optical and structural analyses on organosilicone-coated glass samples were conducted, and the dual-functional layer was applied to the glass cover of a perovskite solar panel to evaluate its performance. The coating not only enhanced light transmission as an AR layer but also converted UV light into blue light, which was absorbed by the solar cell. The results indicated improved solar panel performance, particularly in short-circuit current (Isc), external quantum efficiency (EQE) in the UV wavelength range, and overall efficiency. Overall, this material is a promising candidate for solar panel applications owing to maximized UV absorption for LDS, preserved transparency of the top cover glass, and room-temperature gelation, which facilitates repair of the dual-functional coating. Full article

Improving the absorption of visible light in photocatalysts could enhance photocatalytic reactions and reduce energy consumption, particularly in sunny regions like Ecuador. This study reports the synthesis of ZnO and ZnO nanoparticles doped with 1.5 at.% Er, 5 at.% Al, and 1.5 at.% Er, 5 at.% Al using the sol–gel method. The effect of doping on the structure, morphology, absorption spectra, and photocatalytic properties was analyzed by XRD, SEM, EDS, and UV-Vis spectrophotometry. XRD confirmed the presence of the wurtzite ZnO structure, and UV-Vis diffuse reflection spectra showed a red shift in the band gap for doped ZnO compared to pristine ZnO. Photocatalytic activity was evaluated through the degradation of methyl orange (MO) under artificial visible light and natural sunlight in Quito, Ecuador. ZnO doped with Er/Al nanoparticles exhibited significantly enhanced photocatalytic performance under solar light, suggesting the potential for replacing artificial light and reducing operating costs in photocatalytic processes. Moreover, all doped samples retained the antibacterial properties of ZnO against B. subtilis, and Er/Al co-doping improved the inhibition of E. coli compared to undoped ZnO. Full article

Ozone monitoring in laboratory environments is essential for ensuring personnel safety and maintaining stable experimental conditions, particularly in enclosed facilities where ozone may accumulate during high-energy radiation operations. This study investigates the short-term prediction of ozone concentration using data obtained from a sensor-based ozone monitoring system deployed at the National Synchrotron Radiation Research Center (NSRRC). Ozone concentration measurements were collected using a UV absorption-based ozone analyzer and analyzed as a time-series dataset under controlled experimental conditions. Three forecasting models—Autoregressive Integrated Moving Average (ARIMA), Long Short-Term Memory (LSTM), and linear regression—were evaluated for short-term ozone concentration prediction. Experimental results indicate that the ARIMA model provides superior predictive performance for the small-sample dataset used in this study. In the Right direction, ARIMA achieved R² values of 89.5%, 86.3%, and 81.1% at distances of 5 cm, 10 cm, and 15 cm, respectively, while also demonstrating stable performance in the Up direction. The results highlight the effectiveness of classical time-series models for sensor data analysis in environments with limited sensing data. The proposed framework demonstrates the potential of integrating sensing devices with predictive data analytics to support real-time environmental monitoring and safety management in laboratory facilities. Full article

Reliable analytical methods are essential for the assessment, effective quality control, and guarantee of consistent and reproducible performance of chemical profiles of non-psychoactive low-THC Cannabis sativa L. samples and their products. An integrated analytical approach was applied for the first time to evaluate low-THC C. sativa products on the Serbian legal market using chemometrics combined with five complementary techniques: ultraviolet–visible spectroscopy (UV–Vis), high-performance thin-layer chromatography (HPTLC), portable Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and gas chromatography–mass spectrometry (GC–MS). HPTLC rapidly differentiated key cannabinoids with R_F at 0.39 and 0.61, while GC–MS enabled comprehensive identification of major cannabinoids (CBG and CBD). Spectroscopic fingerprints provided characteristic UV–Vis absorption maximum (215, 235, and 275 nm), Raman (1700, 1550, 1517, 1224, 1096 cm⁻¹) and FTIR marker bands (615, 1059, 1288, 1620, 2932 cm⁻¹), supporting robust monitoring. Principal component analysis (PCA) across all five techniques revealed two major distinct sample clusters and identified the most influential analytical signals. The combined separation, spectroscopic, and multivariate approach is proven to be effective for systematic cannabinoid content assessment, authentication, and chemical profiling within a process-oriented context, thus enabling effective quality control in the cultivation process by targeting compounds of interest. Full article

Background: Guanine-rich DNA regions can fold into G-quadruplex (G4) structures, which are prevalent in telomeres and oncogene promoters, making them attractive targets for anticancer therapeutics. Small molecules capable of selectively stabilizing G4 DNA can disrupt telomerase activity and oncogene expression, offering a promising strategy for cancer intervention. Methods: A rationally designed series of DPPZ–anhydride-conjugated ligands (1 and 2) and their corresponding quaternized derivatives (1-q and 2-q) were synthesized to investigate the combined effects of π-extension, bromine substitution, and cationic modification on DNA recognition. The synthetic strategy relied on the incorporation of a highly planar DPPZ–anhydride scaffold to enhance π-surface area, followed by selective quaternization to introduce permanent positive charge and reinforce electrostatic interactions with the DNA backbone. All compounds were fully characterized by NMR and spectroscopic methods. The DNA-binding properties of the ligands were systematically evaluated toward duplex (ds-DNA) and G-quadruplex (G4-DNA) structures using UV–Vis absorption titration, fluorescence intercalator displacement (FID) assays, and competitive dialysis experiments. Quaternization markedly enhanced intrinsic binding constants and significantly reduced DC₅₀ values, particularly for G4-DNA. While bromine substitution increased overall binding affinity, it did not substantially improve topology selectivity. Among the series, compound 1-q exhibited the most favorable balance between affinity and G4 selectivity. Results: The interaction of the compounds with BSA was quantified using Stern–Volmer quenching constants, which demonstrated a clear trend of enhanced quenching efficiency upon modification. The binding strength followed a descending order of 1-q > 2-q > 1 > 2, highlighting the superior performance of the first series over the second. These findings indicate that the structural features of 1-q facilitate a more robust interaction within the hydrophobic pockets of the protein. Conclusions: Overall, the results demonstrate that strategic π-conjugation combined with electrostatic reinforcement provides an effective approach for the development of topology-selective DNA-binding ligands. Full article

UV-C irradiation enables digital zirconia colouring. This study investigates the atomic mechanism driving this defect-induced optical change. The band gap was calculated from the absorption spectra with the Tauc plot. The absorption spectra were measured using UV–visible spectroscopy. The surface composition was evaluated through X-ray photoelectron spectroscopy (XPS). The location of the oxygen vacancy was tested through electron paramagnetic resonance (EPR). The computer calculation using Density Functional Theory was conducted and the density of states (DOSs) were calculated. The band gap reduced rapidly from the baseline group (3.184 eV) to the 30 min irradiated group (3.097 eV). The XPS results showed that the electron density around O1s reduced and the electron density around Zr 3d increased. The EPR signal (g = 2.0037) increases progressively as the UV-C irradiation time is prolonged from 15 min to 24 h, indicating the accumulation of paramagnetic defect centres. The DOSs suggested the emergence of defect-associated states and band-edge tailing in oxygen deficient models, consistent with the experimentally observed reduction in the Tauc-derived optical band gap. This study confirmed the mechanism by which UV-C-induced oxygen vacancies modify the colour of 3Y-TZP. Full article

Photocatalytic degradation is a highly efficient, stable and promising technology for water treatment. Developing high-performance photocatalysts is crucial for removing aquatic contaminants. However, traditional zinc oxide (ZnO) photocatalysts are severely restricted by intrinsic drawbacks, such as a wide band gap, fast recombination of photogenerated carriers, and high photocorrosion tendency. Conventional powder catalysts also suffer from difficult recovery and serious secondary pollution. Therefore, developing simple strategies to fabricate high-performance, reusable, and stable ZnO-based photocatalysts is of great scientific and practical importance. In this work, silver-loaded nitrogen-doped ZnO nanoarrays (Ag_Y@N_X-ZnO NAs, where X and Y represent the urea and AgNO₃ concentrations, respectively) were synthesized on 304 stainless steel sheets (SSS) using a two-step hydrothermal method combined with photoreduction at room temperature. The samples were characterized by XRD, FESEM, XPS, and UV-Vis DRS, and the catalytic mechanism was studied through active species trapping and EPR. Nitrogen doping and Ag loading exhibited a strong synergistic effect, narrowing the band gap, enhancing visible-light absorption, and promoting the separation of photogenerated carriers. The optimal sample (Ag_1.5@N₄-ZnO NAs) degraded 93.2% of Rhodamine B (RhB) within 180 min, with a reaction rate constant 2.65 times higher than pure ZnO. The main active species were ·O₂⁻ and ·OH. This work provides a feasible route to fabricate recyclable and stable stainless steel-based ZnO nanoarray photocatalysts for efficient water purification. Full article

To address the low utilization rate of straw and environmental pollution caused by traditional processing methods, this study developed a novel composite material based on straw for manufacturing outdoor furniture. Designed to achieve high-value recycling of agricultural waste and enhance the durability and sustainability of outdoor materials, the straw is treated with alkali and processed using an MDI curing system, with the addition of ZnO to enhance functional properties. Characterization of material properties was performed using contact angle measurements, UV-visible spectroscopy, and mechanical testing. The results indicate that a water contact angle of 93.51° was achieved for the composite material at a ZnO content of 6 wt.%, demonstrating excellent hydrophobicity. The introduction of ZnO reduced light absorption, indicating that the material exhibits superior stability in interior and exterior environments. The synergistic interaction between ZnO and straw fibers, along with the resulting active free radicals (·OH), endows this material with hydrophobic and UV-resistant properties. This composite material combines excellent mechanical strength with environmental friendliness, offering broad prospects in the field of sustainable outdoor furniture manufacturing. Full article

This study explores the potential utilization of bioactive glasses using different dopant ions and ketoprofen for both tissue ingrowth and local drug delivery. Four different compositions of vitreous powders were synthesized by the sol–gel combined with the emulsion method, in the presence of the ionic surfactant cetyltrimethylammonium bromide (CTAB), differing by dopant ions: SiO₂- P₂O₅-CaO-(ZnO-MgO). This study investigates the chemical–mineralogical, morphological, and structural characteristics, as well as the biological properties of vitreous materials obtained. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) data analysis confirmed the vitreous nature; scanning electron microscopy (SEM) micrographs correlate with the results of physical absorption with N₂, and the compositions used for the synthesis of the powders all showed for the samples with MgO lower porosity. Biological testing demonstrated biocompatible behavior towards osteoblast cells, (MG-63 type), inducing a slight acceleration of the mineralization phenomenon in the osteoid of the cells compared to the negative control, with cell viability for all the samples higher than 50%. Preliminary release analyses performed by UV–Visible spectroscopy showed a characteristic controlled release profile with prospects for a potential drug delivery system. The zinc–magnesium co-doped sample exhibits optimal performance in both osteogenic promotion and drug delivery, presenting potential for integrated bone repair and local drug administration. This study concludes that the synthesized bioglass exhibits promising characteristics for potential applications in tissue engineering with local drug delivery. Full article

An eco-friendly green synthesis approach was employed to produce copper nanoparticles (CuNPs) using a polyherbal extract derived from two medicinally important plant species, Hygrophila auriculata (Schumach.) Heine and Leucas aspera (Willd.) Link. The plant extracts were initially subjected to phytochemical screening to identify bioactive constituents potentially involved in nanoparticle synthesis. The synthesized CuNPs were characterized using UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), gas chromatography–mass spectrometry (GC-MS), field-emission scanning electron microscopy coupled with energy-dispersive X-ray analysis (FESEM-EDAX), X-ray diffraction (XRD), and thin-layer chromatography (TLC). UV-visible spectroscopy revealed a characteristic absorption peak at 233.6 nm. FTIR analysis indicated the presence of functional groups associated with nanoparticle reduction and stabilization, whereas FESEM imaging showed predominantly spherical particles with sizes ranging 63–68 nm. Elemental composition was confirmed using EDAX analysis. XRD analysis demonstrated polycrystalline nature of the CuNPs, with an average crystallite size of 11.5 nm. GC-MS analysis and phytochemical screening further confirmed the presence of bioactive compounds, whereas TLC analysis revealed differences in mobility between the plant extract and synthesized CuNPs. Antibacterial activity of the synthesized CuNPs was evaluated using the agar well diffusion method against clinically relevant bacterial strains, including those of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Streptococcus pyogenes. The polyherbal-derived CuNPs produced larger inhibition zones than the individual plant extracts, particularly against multidrug-resistant pathogens such as P. aeruginosa and S. aureus. Additionally, the nanoparticles exhibited concentration-dependent antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl assay at concentrations ranging 10–50 mg/mL, with radical scavenging activity increasing from 29.9% to 76.5% and a corresponding decrease in absorbance from 0.698 to 0.234 (p < 0.05). Cytotoxic evaluation in HepG2 cells after 48 h of exposure demonstrated dose-dependent morphological changes and reduced cell viability. These findings suggest that polyherbal-derived CuNPs possess antibacterial, antioxidant, and cytotoxic properties with potential relevance for biomedical applications. Full article