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

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.