Evaluation of Metal-Doped ZIF-8-Hyaluronic Acid Nanocomposites for Disruption of Salmonella Typhimurium and Escherichia coli on Food Contact (Stainless Steel) Surfaces

This study developed and evaluated multifunctional Cu-doped Zeolitic Imidazolate Framework-8 nanoparticles coated with hyaluronic acid (Cu-ZIF-8@HA) for antimicrobial application on stainless-steel food-contact surfaces. Structural characterization through SEM, TEM, and elemental mapping confirmed the successful synthesis, uniform Cu incorporation, and HA coating without compromising the crystalline ZIF-8 framework. Cu doping reduced particle size (~130 nm) and enhanced redox activity, while HA encapsulation improved colloidal stability and biocompatibility by shifting zeta potential from positive (+22.1 mV) to negative (−18.7 mV). Cytotoxicity assays demonstrated that HA significantly mitigated metal-induced toxicity, maintaining >70% cell viability at ≤1000 µg/mL. Antibacterial assessments revealed potent activity against Salmonella Typhimurium ATCC 14028 and Escherichia coli O157:H7, with Cu-ZIF-8@HA exhibiting the largest inhibition zones (18.15–20.33 mm), lowest MIC/MBC values (500/2000 µg/mL and 1000/2500 µg/mL), and over 6-log reductions in bacterial adhesion on stainless steel. Enhanced wettability (contact angle 11.77°) and surface energy (64.42 mN/m) further facilitated antimicrobial contact. These results confirm that Cu-ZIF-8@HA integrates the oxidative potency of Cu, the structural stability of ZIF-8, and the biocompatibility of HA, offering a promising and safe nanomaterial platform for controlling bacterial contamination and biofilm formation in food-processing environments.