Researchers employed the improved Hummers' method to synthesize graphene oxide (GO) from graphite, chosen for its faster kinetics, enhanced safety, and reduced toxicity. Thermal annealing was conducted at 0°C, 200°C, 300°C, and 400°C. The acidity of GO was minimized through repeated centrifugation, rinsing, and decanting. The resulting films were characterized for structural, morphological, elemental, optical, gas-sensing, and photocatalytic properties. FESEM micrographs revealed nanoflake distributions across the substrate, while EDS confirmed elemental composition with precise mass and atomic percentages. Optical analysis showed high absorbance coefficients that increased with annealing temperature. Thermal conductivity was high, and FTIR spectroscopy identified characteristic functional groups. Gas-sensing tests demonstrated peak sensitivity to hydrogen sulfide (H2S) at 100 ppm. Photocatalytic studies revealed a maximum azo dye degradation efficiency of 98.2%, though efficiency decreased with higher annealing temperatures. Pseudo-first-order rate constants (k) increased with annealing temperature, indicating enhanced reaction kinetics. Overall, the synthesized GO variants exhibit promising multifunctional properties, making them strong candidates for integration into gas-sensing and photocatalytic applications.

Two new chalcones derived from coumarin and their corresponding Al(III), Fe(III), Ni(II), and Zn(II) complexes were synthesized. UV-visible absorbance spectra showed ligand-centered π → π* transitions, reducing optical band gaps from 3.20 eV for parent coumarin to 2.94-3.16 eV after conjugation. Solvent polarity also affected absorbance bands, whereas metal complexation preserved band gaps but increased absorbance intensity through ligand-to-metal charge transfer. Photoluminescence spectra exhibited blue-green emission within the range of 432-458 nm, influenced by solvent polarity and the degree of conjugation, with diamagnetic Al(III) and Zn(II) amplifying emission (CHEF effect) while paramagnetic Fe(III) induced significant quenching (CHEQ). Fluorescence lifetimes varied between 0.85 and 4.80 ns for the unbound ligands and 1.12 and 4.63 ns for the complexes; the prolonged yet significantly quenched Fe(III) complexes suggested static quenching, whereas the brief-lived, highly emissive Ni(II) complex demonstrated an increased radiative rate. Cyclic voltammetry showed irreversible anodic oxidation, with HOMO levels from oxidation onsets and LUMO from the optical band gap. Chalcone functionalization increased the HOMO level and cycling stability compared to the parent coumarin, whereas metal coordination, especially with Ni(II) and Zn(II), improved charge-transfer activity and stability without changing the band gap. These findings suggest optoelectronic and photonic applications for coumarin-chalcone derivatives and their metal complexes.

This study presents an eco-friendly approach for the synthesis of zinc oxide (ZnO) nanoparticles using the aqueous leaf extract of Codiaeum variegatum as a plant-derived capping and stabilizing medium. Zinc acetate dihydrate was reacted with the extract in an alkaline medium, followed by drying and calcination to obtain ZnO nanoparticles. The product was characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analysis (TGA/DTA), field-emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD). The synthesized material exhibited the characteristic ZnO absorption near 380 nm and a hexagonal wurtzite structure, with an average crystallite size of 19.21 nm based on the Scherrer analysis. FESEM revealed predominantly spherical to slightly irregular particles with appreciable agglomeration. EDX detected Zn and O together with a sodium signal, with the analyzed region containing 65.12% Zn, 14.39% O, and 20.49% Na. The photocatalytic activity was evaluated using 50 mg L[-1] Basic Violet (BV) under natural sunlight. A degradation of 55.56% was obtained after 150 min in the presence of 0.50 g ZnO in 100 mL of dye solution. The apparent pseudo-first-order kinetic analysis gave k = 5.405 × 10-3 min[-1] with R[2] = 0.9639.

Ferric reducing antioxidant power (FRAP) is a well-established antioxidant in vitro assay. This work introduces an innovative FRAP-analog assay based on green-synthesized carbon dots (GCDs) for the sensitive evaluation of antioxidant activity. The GCDs were prepared via ordinary roasting of sweet potato, which is considered a natural and renewable precursor, yielding highly fluorescent (quantum yield 53%), water-soluble CDs with excellent ferric (Fe[3+]) complexing activity. In this system, the addition of Fe[3+] leads to quenching of the fluorescence of GCDs. Antioxidant-induced reduction of Fe[3+] to Fe[2+] leads to a measurable turn on effect. Using ascorbic acid as a reference antioxidant, the sensor exhibited a linear response between 2 and 14 μg/mL (R[2] 0.996) with a limit of detection of 0.82 μg/mL, very good accuracy (recovery = 103.27% ± 3.48%) and acceptable precision (RSD = 1.01%-5.61%). The developed assay was applied successfully to pharmaceutical products and plant extracts. The GCD-based FRAP analog demonstrated strong correlation with traditional FRAP assays. The devised approach eliminated the use of toxic nonrenewable reagents, rendering it excellent green on both analytical Eco-scale, Analytical GREEnness (AGREE), and Nano Eco-Scale metrics. This green, nanomaterial-based approach provides a promising alternative for antioxidants' analysis in food and pharmaceuticals.

A novel direct spectrofluorimetric method was developed and validated for simultaneous determination of cetirizine hydrochloride (CTZ) and montelukast sodium (MKT), commonly used in COVID-19 combination therapy. Montelukast was determined using first derivative synchronous fluorescence at 422 nm, corresponding to a zero-crossing point for CTZ. Cetirizine was quantified using a newly applied ratio derivative synchronous fluorescence spectroscopy ([1]DD-SFS) technique, using MKT (0.1 μg/mL) as a divisor, allowing CTZ measurement at 293 nm. Cetirizine and montelukast native fluorescence was significantly enhanced by micellar solubilization using cetyltrimethylammonium bromide (CTAB) and sulfuric acid. A two-level factorial design was employed for method optimization, with optimal conditions incorporating 0.5% w/v CTAB and 0.2-M sulfuric acid. Validation was performed according to ICH guidelines, proving the methods specificity, sensitivity, and robustness. The methods demonstrated linearity in the range of 0.1-1.0 μg/mL for MKT and 1.0-10.0 μg/mL for CTZ, with detection limits of 0.017 and 0.415 μg/mL, respectively. The developed methods were applied for MKT and CTZ concurrent determination in laboratory-prepared mixtures simulating tablet formulations. Greenness and practicality were assessed using Eco-Scale, the Complex MoGAPI, AGREE, and BAGI establishing the method as eco-friendly and suitable for routine quality control.

Fluorescent probes are widely employed in biofluorescence analysis and biomedical imaging. In this study, uniform spherical silica-encapsulated silicon-nitrogen co-doped carbon dots (Si-MPD-CDs@SiO2) with a particle size of 24 ± 15 nm were prepared via a modified Stöber method. The nanocomposites were further carboxylated and covalently conjugated with Protein A to construct Si-MPD-CDs@SiO2@PA bioconjugates. The resulting nanoprobe was successfully applied for specific immunofluorescence labeling and imaging of immortalized mouse thymic epithelial cells (iTECs). Compared with commercial fluorescent secondary antibodies, Si-MPD-CDs@SiO2@PA exhibit multiple superiorities including low cost, facile preparation and purification, favorable surface modifiability, strong fluorescence emission, and high photostability. These results indicate that Si-MPD-CDs@SiO2@PA can serve as a promising fluorescent nanoprobe for targeted cellular imaging and related biomedical applications.

A suite of BaGaBO4:x(Eu[3+], Tb[3+]) new fluorescent powders fabricated via high-temperature solid phase method. These samples were characterized by XRD, SEM, and EDS. The photoluminescence results indicated that BaGaBO4:xEu[3+] could emit red light, and the emission spectra are 592 and 613 nm when the excitation spectrum is 394 nm. While BaGaBO4:xTb[3+] could emit green light, the emission spectra are 489 and 544 nm when the excitation spectrum is 242 nm. The fluorescence lifetime of BaGaBO4:0.07Eu[3+] is 1.782 ms, and BaGaBO4:0.07Tb[3+] is 2.217 ms. The CIE coordinate of BaGaBO4:0.07Eu[3+] is (0.633, 0.367), color purity is up to 99.7%, and PLQY is 84%. The CIE coordinate of BaGaBO4:0.07Tb[3+] is (0.221, 0.616), and color purity is 70.7%. At 423 K, the percentage of emission spectral intensity is 81.19% for BaGaBO4:0.07Eu[3+] of its initial value at 298 K, while that of BaGaBO4:0.07Tb[3+] is 83.89%, which show that BaGaBO4:0.07Eu[3+] and BaGaBO4:0.07Tb[3+] possess good thermal stability.

An N-doped carbon dot was hydrothermally (one-pot) prepared from citric acid (C-source) and isonazid (N-source) in 1:4.2 ratios. It has an amorphous-nanocrystalline turbostratic carbon system consisting of N-disrupt core sp[2]/sp[3] carbon with highly integrated nitrogen, whereas in the outer sp[2] carbon shell with excess nitrogen creating densely and multifaceted groups (amine, amide, and pyridinic). The characteristic broad pxrd peak at 22.40° (002) and a hump 44.70° (100) were obtained with particle size ≈8.0-9.0 nm in quasispherical form with distinct lattice d-spacing value. The N-CDs gain highly hydrophilicity and dispersibility in water. The N-CDs possess excellent optical properties with long range (350-600 nm) blue-green fluorescence caused by electron trapping in N-surface states and radiative recombination (Ф = 32%). This fluorescence emission is selectively quenched upon interaction with Fe[3+] ions in pool of various metal ions. The quenching mechanism involves the locking of electron trap N-surface states caused by Hard Acid-Hard Base complexation of Fe[3+] ions with multifunctional N and O containing groups leading to Photoinduced Electron Transfer. The linear quenching and regression coefficient reveal a highly sensitive (LOD = 99.4 nM), strong binding and static quenching. Practical application in real water sample analysis and anticounterfeiting ink test was demonstrated.

Indium phosphide (InP) quantum dots (QDs) have emerged as promising cadmium-free luminescent nanomaterials for near-infrared (NIR) bioimaging and theranostic applications owing to their tunable optical properties, photostability, and improved biocompatibility. This review highlights recent advances in the photophysical engineering of InP QDs, focusing on the mechanisms that govern NIR luminescence, including quantum confinement, excitonic relaxation, defect-state modulation, and band-edge fine-structure effects. The influence of molecular-level surface engineering, such as ligand optimization, core/shell heterostructure design, interfacial alloying, and oxidative passivation, is critically discussed in relation to emission efficiency, colloidal stability, and environmental resistance. Recent studies demonstrating extended NIR emission, multiplexed bioimaging, resonance energy transfer-based sensing, and image-guided therapeutic applications underline the growing biomedical potential of InP QDs. In addition, current knowledge regarding biodistribution, biotransformation, and biological interactions is assessed to better understand their in vivo performance and safety. Despite significant progress, challenges related to long-term stability, degradation pathways, scalable manufacturing, regulatory approval, and clinical implementation remain. Overall, this review provides an integrated perspective on the relationships between photophysical properties, surface chemistry, and biological behavior, offering strategic directions for the development of efficient luminescent InP QDs for next-generation biomedical applications.

Iodine-functionalized graphene oxide (i-FGO) was synthesized through a one-pot, transition-metal-free approach under ambient conditions. An optimized oxidation strategy was developed by replacing conventional H2SO4 with a combined piranha solution, NaIO4, and m-CPBA system to achieve efficient oxidation of the graphite framework. The method enabled simultaneous oxidation and iodine intercalation, producing enhanced functionalization and improved structural properties compared with the previously reported i-GO system. m-CPBA promoted the formation of abundant epoxide groups on the graphene basal planes, while the modified oxidation environment facilitated uniform functionalization throughout the carbon framework. Compared with our previously reported NaIO4-based oxidation method, the optimized piranha-assisted strategy reduced NaIO4 consumption by approximately 38% while maintaining effective oxidation and iodine functionalization. The incorporation of iodine and oxygen-containing functional groups was confirmed using P-XRD, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier-transform infrared (FT-IR) analyses. UV-visible absorption and photoluminescence studies revealed the distinctive optical properties of i-FGO and its sensitive fluorescence response toward Cu[2+] ions, attributed to photo-induced electron transfer (PET) and intramolecular charge transfer (ICT) mechanisms. The developed i-FGO chemosensor exhibited excellent selectivity for Cu[2+] ions in complex systems, with minimal interference from other competing metal ions, demonstrating its promising potential for selective, sensitive, and reliable fluorescence-based Cu[2+] detection in environmental samples.

Triplet-state carbonyl species can be generated in vivo through the oxidation of suitable substrates catalyzed by heme proteins and peroxynitrite, suggesting their involvement in metabolic processes and oxidative stress. In this work, we identified the formation of electronically excited triplet-state acetone during the aerobic oxidation of isobutanal (IBAL) initiated by ferrimyoglobin (ferriMb). This system was compared with the well-established IBAL/horseradish peroxidase (HRP) chemiluminescent reaction. Evidence for triplet acetone formation included Soret band spectral changes during the reaction, ultraweak light emission, and sodium 9,10-dibromoanthracene-2-sulfonate (DBAS)-promoted enhanced emission, as well as quenching by diene quenchers like sorbic acid and ethyl sorbate. Oxygen uptake measurements obeyed first-order kinetics in oxygen concentration for the ferriMb system. Induced structural modification of ferriMb by IBAL was identified. Together, these findings suggest that ferriMb may drive the generation of harmful triplet species under carbonyl stress. Notably, rhabdomyolysis is reportedly known as an injurious condition in which free myoglobin is present in the bloodstream.

Heavy metal-induced environmental degradation has become a pressing concern. Soil enzymes are the products of plant, animal, and microbial activities in the soil. Participating in diverse soil biochemical processes, their activity levels serve as sensitive indicators of biochemical process intensity in soil ecosystems. In this paper, the toxic effects of Cu[2+] on glutamate dehydrogenase (L-GDH), copper/zinc-superoxide dismutase (Cu/Zn-SOD), and acid phosphatase (ACP) were investigated under simulated physiological conditions. Fluorescence spectra and lifetime measurements showed that Cu[2+] reduced the fluorescence intensity and hydrophobicity and altered the protein conformation of L-GDH, Cu/Zn-SOD, and ACP; the intrinsic fluorescence of L-GDH and Cu/Zn-SOD underwent dynamic quenching, whereas ACP underwent static quenching. Enzyme activity assays revealed that ACP was the most susceptible to Cu[2+] inhibition among the three enzymes, showing a clear dose-dependent effect. UV-Vis and CD spectroscopy showed that Cu[2+] loosened the protein backbone structure and induced peptide chain extension and protein unfolding. The changes of enzyme activity in Eisenia fetida were measured after exposure to Cu[2+] at different times and concentrations. Overall, this study provides a foundation for understanding the effects of Cu[2+] on the structure and function of soil enzymes, revealing the potential effects of heavy metals on enzymes.

Dopamine hydrochloride (DPH) is a key neurotransmitter, and its dysregulated concentration has been linked to various neurological disorders. Meanwhile, potassium permanganate (MnO4 [-]), a potent oxidant, poses significant environmental risks when discharged in excess. Therefore, sensitive detection of MnO4 [-] and DPH is essential. In this work, nitrogen, sulfur, and fluorine tridoped carbon dots (N,S,F-CDs) were prepared through a hydrothermal route using Aconitum pendulum Busch extract as a biomass-derived carbon source, with thiourea and sodium fluoride serving as heteroatom dopants. The obtained N,S,F-CDs exhibited bright blue emission, good aqueous dispersibility, and a fluorescence quantum yield of 43.16%, with strong emission at 408 nm under 345-nm excitation. Upon addition of MnO4 [-], the fluorescence was efficiently suppressed owing to the combined contribution of inner-filter effect and dynamic quenching. Subsequent introduction of DPH reduced MnO4 [-] and recovered the fluorescence signal, enabling the construction of an "ON-OFF-ON" sensing platform. Under optimized conditions, the sensor displayed linear responses of 5.03-275.23 μM for MnO4 [-] and 6.11-371.02 μM for DPH, with detection limits of 0.25 and 0.68 μM, respectively. The method was further applied to tap water, serum, and orange juice samples with satisfactory recoveries, indicating its potential for environmental and bioanalytical detection.

A rapid, sensitive, and sustainable fluorimetric method based on fluorescence quenching of nitrogen-doped carbon quantum dots (N-CQDs) is introduced for the first time to determine betahistine dihydrochloride (BTH). The N-CQDs were prepared via a simple hydrothermal approach and characterized using transmission electron microscopy for electronic structure and morphology, ultraviolet-visible absorption spectroscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy, confirming their nanoscale structure, elemental composition, and surface functionalization. The N-CQDs gave strong blue emission at 440.0 nm upon excitation at 345.0 nm. BTH-induced concentration-dependent quenching of N-CQDs fluorescence was mainly due to static quenching. Under optimized conditions, the proposed method showed excellent linearity over the concentration range of 0.025-4.00 μg/mL. The method was successfully applied to pharmaceutical dosage forms, content uniformity testing, and urine samples, providing accurate results with satisfactory recoveries and good precision, without interference from common excipients or matrix components. Notably, the procedure operates entirely in distilled water, requiring minimal reagents with a short incubation time, highlighting its simplicity and practicality. The greenness and sustainability of the developed method were quantitatively evaluated and confirmed using the carbon footprint reduction index (CaFRI), the newly developed Nanomaterials Assessment Tool (NAT), and an integrated NQS-SAMI assessment.

The development of photoluminescent Ni(II) complexes has recently attracted growing interest. However, it is highly challenging, and photoluminescent Ni(II) complexes are very rare. In this work, a square-planar Ni(II) complex bearing a rigid tetradentate naphthyridine-fused dicarbene diphenolate ligand, Ni(NpC2O2), was designed and synthesized. The complex exhibits blue ligand-originated fluorescence in DCM at room temperature. At 77 K, it shows weak phosphorescence at 515 nm with a lifetime of 51.8 μs in a frozen 2-MeTHF matrix. Based on the experimental studies and DFT/TD-DFT calculations, it is plausible that the phosphorescence originates from the T7/T8 state(s) via a high-lying intersystem crossing (HISC) process from the S3 state. The assignment of anti-Kasha phosphorescence is in line with the excitation-dependent phosphorescence at 77 K. This work demonstrates that rigid and fused carbene ligands might be promising to light up Ni(II) complexes.