Research on pH-responsive Antibacterial Materials Using Citral-modified Zinc Oxide Nanoparticles

Abstract

Abstract With the deepening of the harm of foodborne pathogens to human health and the increasing attention of people to healthy diet, novel food antimicrobial agents have been widely studied by researchers as hotspots. In this study, three different morphologies of citral-modified ZnO nanopaticles antimicrobial materials were prepared, and the citral-modified porous ZnO nanorods antimicrobial materials with the highest loading (60.35%) and the strongest inhibitory effect (MIC = 0.2 mg/mL ~ 0.1 mg/mL) were screened out through a series of characterization and bacterial inhibition experiments. This novel antimicrobial material has excellent and long-lasting antimicrobial properties. It inhibits Escherichia coli by 100% when stowed at 25°C and protected from light for 10 days, and inhibits the growth of E. coli by 58.17% after being stowed under the same conditions for 60 days. Furthermore, we tested the pH change during 24 hours of E. coli growth and pH responsiveness of the materials. The results demonstrated that under the acid-producing condition of E. coli growth, the pH-sensitive imine bond (-CH=N-) formed by the condensation of amino of functionalized ZnO nanoparticles and citral was hydrolyzed to release the citral, thus indicating that the release mechanism of citral in the antibacterial material was pH-sensitive acid release in the process. The antibacterial materials in this study have broad application prospects in the field of food production and packaging in the future. Meanwhile, this study provides a theoretical basis for guaranteeing food quality and safety.