Ag-decorated ZnO/MgO nanocomposite derived from Cinnamomum camphora: Synthesis and functional evaluation

Abstract The escalating threat of antimicrobial resistance and the limitations of conventional cancer therapies necessitate the development of novel, multifunctional agents. This study establishes the first eco-friendly protocol for synthesizing a trimetallic Ag/ZnO/MgO nanocomposite (NC) using an aqueous leaf extract of Cinnamomum camphora L. Response Surface Methodology (RSM) optimized the synthesis conditions to pH 8.03, 37.8°C, and 3.37 hours. Comprehensive characterization via UV-Vis, FTIR, XRD, SEM-EDX, elemental mapping, TEM, DLS, Zeta potential, and TGA analysis confirmed the formation of a spherical, crystalline nanocomposite with an average size of ~ 48–59 nm and a macroporous structure. Phytochemical profiling revealed the extract’s richness in flavonoids, phenolics, and tannins, which facilitated the bio-reduction and capping processes. The biosynthesized Ag/ZnO/MgO NC demonstrated potent, broad-spectrum antibacterial activity against Staph. aureus , Bac. subtilis , Esch. coli , Kleb. pneumoniae with minimum inhibitory concentrations (MICs) as low as 62.5 µg/mL. It significantly inhibited biofilm formation in S. aureus and E. coli (up to 85%) and downregulated associated virulence genes ( icaA , icaD , papC , fimH ). Furthermore, the nanocomposite displayed significant cytotoxicity toward Mcf-7 breast cancer cells (IC₅₀ = 118.0 µg/mL) while exhibiting significantly lower toxicity to normal Vero cells (IC₅₀ = 332.7 µg/mL). Mechanistic studies revealed that the nanocomposite exerted its anticancer effect by activating apoptotic pathways and causing cell cycle arrest at the S and G2/M phases. The NC also displayed notable antioxidant (DPPH IC₅₀ = 150.1 µg/mL) and lipase inhibitory (IC₅₀ = 108.4 µg/mL) properties, indicating anti-obesity potential. These findings underscore the Ag/ZnO/MgO nanocomposite as a promising, multi-target therapeutic agent with significant potential for combating drug-resistant infections, cancer, and oxidative stress-related disorders.