Fluorescent carbon dots (CDs) were efficiently synthesized by a one-step microwave-assisted method using diphenylamine as a carbon precursor. The obtained CDs exhibit high stability and strong water solubility. Under UV irradiation, these CDs could emit bright green photoluminescence. These synthesized CDs have an average diameter of 1.8 nm (±0.46) and quantum yield (QY) as high as 44.69% using rhodamine-B as a reference. The CDs’ intensity can be quantitatively quenched by Hg²⁺ and Fe³⁺ ions with high sensitivity and low LOD about 9.58 nM and 22.27 nM, respectively, indicating that the CDs sensors can be potentially applied for Hg²⁺ and Fe³⁺ detection in aqueous solutions.

Since it is expensive and takes considerable time to synthesize a new drug or improve an old one, a drug carrier can be used instead for control and targeted release of the drug. In this study, hydrogel beads were used as drug carriers for the controlled release of doxorubicin hydrochloride. Aiming to incorporate doxorubicin hydrochloride into hydrogel, various metal crosslinked alginate beads were prepared. Doxorubicin hydrochloride was incorporated by adsorption into the beads and studied the factors affecting the adsorption of drug onto the hydrogel beads. The results showed that ferric crosslinked alginate (Fe(III)–Alg) and stannous crosslinked alginate (Sn-Alg) hydrogel beads had a better adsorption percentage which was more than 21%. The amount of hydrogel, time, drug concentration, and pH of the solution all influenced the adsorption percentage. Hence, the adsorption was the best at neutral pH after 24 h when 100 mg of Fe(III)–Alg was added to the drug. Moreover, the release of the drug at different body simulation pH was investigated. The time and pH of the solution influenced the drug release where maximum drug release percentage was 82.822% after 25 h when the solution’s pH was 1.52. This system is assumed to follow the Higuchi kinetic release model.

This study explores the green synthesis of silver-doped lanthanum oxide (La/Ag), silver-doped yttrium oxide (Y/Ag), and silver-doped lanthanum–yttrium oxide (La/Y/Ag) nanocomposites using Catharanthus roseus extract as a natural reducing and stabilizing agent. The nanocomposites were characterized using various spectroscopic techniques to confirm their morphology, composition, crystallinity, and functional groups. La/Ag, Y/Ag, and La/Y/Ag exhibited significant catalytic activity in the reduction and degradation of methylene blue (MB), methyl orange (MO), acridine orange (AO), and 4-nitrophenol (4-NP). Optimization studies showed that La/Ag achieved complete MB reduction within 3 min, while La/Y/Ag reduced MO in 90 s. Both catalysts maintained high activity over multiple cycles, with only slight efficiency loss. In real water media, La/Ag and La/Y/Ag achieved reduction efficiencies of 98% and 97%, respectively. La/Ag also demonstrated excellent photocatalytic degradation of AO under UV light, achieving complete degradation in 80 min, and 98% degradation in tap and seawater samples. Additionally, the nanocomposites demonstrated broad-spectrum antimicrobial activity against bacterial and fungal pathogens, with varying inhibition levels across species.

Using orange peels as a biowaste, fluorescent N-CDs were prepared simply and rapidly through a one-step microwave-assisted method and urea as a nitrogen source. The synthesized N-CDs exhibited a high QY value of 47.12% compared to CDs prepared using different methods. Moreover, the N-CDs have good pH and thermal stability. N-CDs exhibited high sensitivity toward Fe(III), Hg(I), and Hg(II) ions with low LOD values of about 0.0555, 0.15379, and 0.02505 μM, respectively. This approach is hopeful for the large-scale formation of N-CDs and could encourage their utilization as fluorescent chemosensors due to their affordability, simplicity, high efficiency, and environmental friendliness.

This study reports a sustainable and experimentally simple electrochemical platform for monitoring trace Pb²⁺ using pumpkin peel-derived carbon black (CB) as a modifier on a Nafion-coated glassy carbon electrode (CB/Nafion-GCE). Agricultural waste pumpkin peels were converted into CB, offering a low-cost and environmentally friendly sensing material. CB produced at 650 °C was systematically characterized by SEM, TEM, EDX, XRD, FT-IR, and BET, revealing a mesoporous structure, high surface area, and partial graphitization that enlarged the electroactive area and reduced charge transfer resistance relative to the bare GCE. Under optimized square wave anodic stripping voltammetry (SWASV) conditions, the glassy carbon electrode modified with CB produced at 650 °C (CB650-GCE) exhibited a well-defined linear response towards Pb²⁺ with a limit of detection of approximately 0.19 µM and a limit of quantification of about 0.58 µM, together with good selectivity against common coexisting metal ions. The sensor also achieved satisfactory recoveries in tap and seawater samples, demonstrating its potential as a practical, green analytical tool for routine lead surveillance in environmental waters.

Chicken bile-mediated silver nanoparticles (Ag-NPs) were synthesized and evaluated via UV–Vis, SEM, FTIR, and XRD. The synthesis of Ag-NPs was validated by observing a color change that was visible to the naked eye and via UV–Vis spectroscopy. A peak at 435 nm in the UV–Vis spectrum suggest the formation of Ag-NPs. The FTIR spectrum indicated that Ag⁺ reduction into Ag-NPs may occur due to proteins that are present in chicken bile. The XRD results showed that the nanoparticles were crystalline in nature, with a crystallite size of 25 nm. The SEM images showed that spherical-shaped nanoparticles with an average size of 20–60 nm were formed. The effects of different parameters, such as extract concentration, pH, and temperature, on the shape and reaction rate of Ag-NPs were examined. The results showed that the formation of Ag-NPs increased substantially in basic medium and they were found to be more stable at 60 °C. The prepared Ag-NPs were evaluated for their antibacterial activity and photocatalytic efficiency in degrading Disperse Orange 1 (DOI) dye. The antibacterial assessment of the synthesized Ag-NPs showed significant antibacterial activity. Based on the photodegradation study, it was found that the synthesized Ag-NPs showed high activity and almost complete (97%) degradation of DOI within the first 100 min. Thus, the overall results reveal that the prepared Ag-NPs offer a better approach for remediating the aforementioned contaminants.