Green-synthesized curcumin-zinc nanocomplexes: Enhanced antioxidant/ antibacterial activity and pH-Responsive release properties

Microbial contamination significantly accelerates food spoilage and poses serious risks to public health, thereby necessitating the urgent development of eco-friendly antimicrobial materials to ensure food safety and mitigate health hazards. In this study, a curcumin-zinc complex (Cur-Zn) was synthesized through a hydrothermal method under alkaline conditions, resulting in a metal-polyphenol composite targeted for antibacterial applications. The optimized Cur-Zn (at pH 8, 80 degrees C) exhibited a spherical nanostructure (30-40 nm) with a substantial Zn2+ content of 13.56 % (m/m) and exceptional aqueous dispersibility. Cur-Zn demonstrated the pH-responsive release kinetics of curcumin, adhering to a first-order model in acidic environments, and exhibited superior antioxidant capacity compared with that of the physically mixed components. Notably, Cur-Zn effectively inhibited the growth of E. coli and S. aureus by disrupting bacterial membranes while concurrently reducing intracellular reactive oxygen species (ROS) levels under oxidative stress at safe dosages. This investigation underscores the dual antioxidative and antibacterial functions of Cur-Zn and its pH-triggered release mechanisms, thereby presenting a green strategy for the design of metal-phenolic antimicrobial agents.