Evaluation of Green-synthesized Zinc Oxide Nanoparticles for Antibacterial, Antioxidant, and Anticancer Properties with Application in Sunscreen Formulation

Background: Zinc oxide nanoparticles (ZnONps) are safe, affordable, and versatile, with strong ultraviolet (UV) absorption and visible light transparency, making them excellent sunscreen agents. Plant extract-mediated synthesis of ZnONps provides an eco-friendly substitute for conventional chemical approaches by avoiding toxic reagents and provides bioactive properties. The study aims to develop non-comedogenic cream formulation using green synthesized ZnONps using the extract of Senna alata and Zingiber officinale - Allium sativum together which possess antibacterial, UV absorption, antioxidant, and anticancer properties. Methods: The characterization was performed using UV-visible spectroscopy, Field Emission Scanning Electron Microscopy, X-ray diffraction, and Fourier Transform Infrared (FTIR) spectroscopy. Antibacterial activity evaluated against Escherichia coli and Staphylococcus aureus . The antioxidant activity was determined by the 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) assay. The anticancer properties were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay using HeLa cells. The Sun Protection Factor (SPF) of the cream formulated by the incorporation of ZnONps was determined. Results: The crystalline sizes of ZnONps synthesized using S. alata leaf and a mixture of Z. officinale-A. sativum extract were 16.98 nm and 92.30 nm, respectively. The FTIR and DPPH assay results showed the presence of phytochemical residue. The antibacterial activities of synthesized ZnONps from the combination of A. sativum and Z. officinale extract have displayed better inhibition ( S. aureus : 14.67 ± 0.35 mm) against gram-positive bacteria and gram-negative bacteria ( E. coli : 22.63 ± 0.62 mm) than those made with S. alata extract ( E. coli 14 ± 0.32 mm and S. aureus 19.4 ± 0.17 mm). The formulated cream showed skin-friendly pH with SPF more than 15. Conclusion: The biosynthesized ZnONPs exhibited antimicrobial, anticancer, and antioxidant potential and can be exploited in bioactive cosmetic formulations.