Green-synthesized Ag-TiO2/chitosan-cyclodextrin films for enhanced antibacterial activity and prolonged mango preservation

Abstract

Tropical fruits are highly perishable and prone to bacterial attacks, leading to spoilage and reduced post-harvest quality. This study addresses the need for eco-friendly preservation solutions by developing biodegradable antibacterial films based on Ag-TiO2 nanoparticles integrated into a chitosan-cyclodextrin (CS-CD) matrix. AgTiO2 nanoparticles were synthesized using a green chemistry approach, employing orange peel extract as a natural reducing agent. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses confirmed that Ag ions partially replaced Ti4+ in the TiO2 lattice, enhancing visible light absorption, antibacterial activity, and reactive oxygen species (ROS) generation. The 3 %Ag-TiO2/CS-CD composite demonstrated exceptional antibacterial efficacy, achieving 100 % inhibition against gram-positive (Staphylococcus aureus, Lactobacillus fermentum) and gram-negative (Salmonella enterica, Escherichia coli, Pseudomonas aeruginosa) bacteria, with minimum inhibitory concentrations (MIC) below 2.3 mu g/mL for key strains. Applied to mango preservation, the 3 %Ag-TiO2/CS-CD film extended shelf life up to 15 days without observable spoilage by preventing water vapor loss and bacterial growth through ROS-mediated mechanisms. Electrochemical characterization provided insights into the band structure and radical formation pathways responsible for the material's antibacterial performance. This research highlights the potential of Ag-TiO2/CS-CD films as sustainable, biodegradable solutions for fruit preservation, non-toxicity, offering enhanced antibacterial activity and prolonged shelf life while minimizing environmental impact.