Green synthesis of sea buckthorn-mediated ZnO nanoparticles: Biological applications and acute nanotoxicity studies

Abstract Plant-based nanoparticle synthesis is the primary focus of modern nanotechnology to reduce the toxicity risk and ensure environmental safety. Zinc oxide nanoparticles (ZnO-NPs) were synthesized in the present investigation using an aqueous extract composed of sea buckthorn berries, adopting a biogenic approach. The green synthesized ZnO nanoparticles (NPs) exhibited a significant absorption peak near 370 nm in the UV–Vis spectrum. Fourier transform infrared study revealed the functional moieties responsible for the stability and capping of ZnO-NPs. The average particle size of the synthesized ZnO-NPs was 52.6 ± 12.51 nm, and their morphologies ranged from spherical to irregular, as indicated by the field emission scanning electron microscopy analysis. X-Ray diffraction study revealed the hexagonal wurtzite-structured NPs with an average particle size of 19.2 nm. The zeta potential of −20 mV indicated the colloidal stability of synthesized NPs. The biogenic ZnO-NPs were assessed for their antioxidant, antidiabetic, and anti-lipid peroxidation potential, where ZnO-NPs have shown better activity than the berry extract. Notably, the antimicrobial efficacy of the synthesized ZnO-NPs was observed against Gram-positive bacteria Staphylococcus aureus MTCC 3160 and Gram-negative bacteria Escherichia coli MTCC 1698, with the zone of inhibition observed as 18 ± 0.23 mm and 39 ± 1.24 mm, respectively. The minimum inhibitory concentration for S. aureus and E. coli was reported to be 0.5 and 1.0 mg·mL −1 , respectively. The LC 50 for Daphnia was reported to be 16.09 mg·mL −1 , confirming the safety of the green-synthesized ZnO-NPs.