In recent decades, antibiotics have been found in aquatic environments, raising severe concerns. In this study, a unique reduced graphene oxide-zinc sulfide-copper sulfide (rGO-ZnS-CuS) nanocomposite (NC) prepared by using a straightforward surfactant-free in situ microwave method was used for antibiotic degradation via photocatalysis. The structural and morphological characteristics of the produced catalysts were characterized using various techniques, confirming the successful development of nanocomposite structures of better quality than that of the pure samples. The photocatalytic degradation of antibiotics containing ofloxacin was also investigated. The results suggest that the rGO-ZCS NC outperformed the other composites in terms of photocatalytic activity toward ofloxacin degradation. Superoxide and hydroxyl radicals were the main active species during the degradation process. According to our results, the catalytic activity of rGO-ZCS NC is much better than that of the other composites.

To explore the larvicidal activity of the silver nanoparticles (AgNPs) synthesized using the ethanolic Catharanthus roseus flower extract (CRE) against the larvae of Aedes aegypti (A. aegypti), AgNPs were synthesized by an eco-friendly method and characterized by Ultraviolet-Visible (UV-Vis) spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Particle Size Analysis, Transmission Electron Microscopy (TEM), and Energy-Dispersive X-Ray spectrometry (EDX) analysis. The resultant AgNPs showed a spherically well-defined, highly stable, and monodispersed shape with an average particle size ranging from 15 to 25 nm. The absorbance of the AgNPs was measured by using a UV-Vis spectrophotometer at a wavelength of 416 nm. The presence and binding of the phenolic functional group with the AgNPs were confirmed using FTIR analysis. Particle size analysis revealed an average particle diameter of 90 nm with 80 % distribution. XRD analysis revealed the highly crystalline nature of the CRE-AgNPs. The LC₅₀ and LC₉₀ values of CRE-AgNPs and the extract were calculated. The mortality percentage of the extract and synthesized CRE-AgNPs was observed after 24 h. The maximum larvicidal activity with 100 % mortality of A. aegypti was observed in AgNPs synthesized using ethanolic CRE. The LC₅₀ and LC₉₀ values are 8.963 and 20.515 ppm for CRE-AgNPs against A. aegypti larvae, respectively. The CRE-AgNPs revealed superior antibacterial activity against human pathogenic bacteria; the zone of inhibition (ZOI) was measured for all of the pathogens, and the results revealed that different concentrations of CRE-AgNPs showed a remarkable ZOI of about (a) 10-14 mm for Salmonella typhimurium, (b) 6-11 mm for Bacillus subtilis, (c) 11-14 mm for Enterococcus faecalis, and (d) 9-10 mm for Shigella boydii. The maximum ZOI was observed in E. faecalis. Impeccably, the cytotoxicity of CRE-AgNPs at 250 μg/mL is 82% against the HaCaT cell lines. The synthesized CRE-AgNPs showed maximum effectiveness of paradoxical activity on mosquito larvae.

Melamine (C ₃ H ₆ N ₆ ) is a commercially synthesised organic compound which is illegally added to milk during processing to boost the apparent protein content. Melamine cannot be metabolised by the body and forms insoluble crystals which causes tissue damage and renal dysfunction. Hence, there is a need to develop a rapid and reliable method for melamine detection. Attempted here is to develop a simple procedure to detect melamine in milk using silver nanoparticles (AgNPs). Borohydride‐reduced AgNPs, citrate‐capped AgNPs and polyvinyl pyrrolidone‐capped AgNPs are synthesised and characterised for their size, composition, structure etc. and studied for the suitability in this application. The first two NPs are determined to be suitable for this detection and exhibit a colour change from pale yellow to red at different concentration of melamine. To measure the melamine concentration, quantification of colour change and the transmitted light intensity is done using a colour sensor when the mixture is exposed to standard light source. Compared with visual observation in colour change, the transmitted light intensity provides more information to quantify melamine, more specifically citrate‐capped AgNPs are found to provide better results than borohydride‐reduced AgNPs. The results of this study are much agreeable to that obtained through standard laboratory experiment. Hence, this proposed method would be useful in developing an electronic‐based melamine testing instrument that can be used rapidly at home.