Selenium nanoparticles (Se NPs) have recently received much interest due to their low toxicity, high bioavailability, and wide applications. This study synthesized Se NPs using selenious acid as a starting material and leaf extract from Elaeagnus indica as a reducing agent. Spectroscopic and electron microscopy investigations have demonstrated the production of aggregated amorphous Se NPs with phytochemicals. Furthermore, the reduction of selenious acid into Se NPs by phytochemicals present in the leaf extract of E. indica was confirmed in a prominent band at 269 nm in the UV-visible spectrum. The biosynthesized selenium nanoparticles have a 10–15 nm particle size distribution. The agar well diffusion assay exhibited remarkable dose-dependent, wide-spectrum antimicrobial efficacy of the Se NPs against all the tested microorganisms. Moreover, the lowest minimum inhibitory concentration (10 µg/mL) was noted against Salmonella Typhimurium and Fusarium oxysporum. The prepared Se NPs degraded methylene blue dye by about 89% after 6 h of exposure to sunlight. In conclusion, the synthesis of Se NPs using E. indica leaf extract shows promise as a method for producing Se NPs with significant antimicrobial activity and potential for methylene blue photodegradation. These properties make them potentially valuable in various fields, including water treatment and biomedical applications, in the future.

Zirconium dioxide nanoparticles (ZrO₂ NPs) have gained significant attention due to their excellent bioavailability, low toxicity, and diverse applications in the medical and industrial fields. In this study, ZrO₂ NPs were synthesized using zirconyl oxychloride and the aqueous leaf extract of Toddalia asiatica as a stabilizing agent. Analytical techniques, including various spectroscopy methods and electron microscopy, confirmed the formation of aggregated spherical ZrO₂ NPs, ranging from 15 to 30 nm in size, with mixed-phase structure composed of tetragonal and monoclinic structures. UV–visible spectroscopy showed a characteristic band at 281 nm with a bandgap energy of 3.7 eV, indicating effective stabilization by the phytochemicals in T. asiatica. EDX analysis revealed that the NPs contained 37.18 mol.% zirconium (Zr) and 62.82 mol.% oxygen. The ZrO₂ NPs demonstrated remarkable photocatalytic activity, degrading over 95% of methylene blue dye after 3 h of sunlight exposure. Additionally, the ZrO₂ NPs exhibited strong antibacterial effects, particularly against Gram-negative bacteria such as E. coli, and significant antioxidant activity, with low IC₅₀ values for hydroxyl radical scavenging. In conclusion, the green synthesis of ZrO₂ NPs using T. asiatica leaf extract is an effective, eco-friendly method that produces nanoparticles with remarkable antioxidant, antimicrobial, and photocatalytic properties, highlighting their potential for applications in water treatment, environmental remediation, and biomedicine.