Chitosan from shrimp shell waste as a carrier for frankincense nanoparticles with enhanced antimicrobial activity

This study focuses on the sustainable extraction of chitosan from shrimp shell waste and its application in developing frankincense-loaded chitosan nanoparticles with enhanced antimicrobial efficacy. Chitosan was extracted through demineralization with 4% HCl, deproteinization using 8% NaOH at 70 °C, and deacetylation with 40% NaOH under shaking for 48 h, yielding 3.4 g (22.51%) from 15 g of shrimp shell powder. Frankincense ethanolic extract was incorporated into chitosan nanoparticles using sodium tripolyphosphate as a crosslinker, followed by ultrasonication and dropwise addition of chitosan to form a stable nanocomposite. Characterization confirmed a semi-crystalline structure (XRD), typical thermal degradation (TGA), and strong molecular interaction between chitosan and frankincense (FTIR). TEM and SEM showed well-dispersed, amorphous nanoparticles with smoother surfaces, while DLS revealed an average particle size of 8.47 nm, PDI 0.6, and zeta potential + 12.9 mV, indicating moderate stability. Antimicrobial activity was evaluated using two methods: the well diffusion and microplate reader assays against Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Salmonella typhi, and Candida albicans. Results showed that nanoparticles significantly enhanced inhibition of S. mutans, S. typhi, and C. albicans compared to the extract. These findings highlight chitosan-frankincense nanoparticles as a promising natural antimicrobial system for pharmaceutical and food preservation applications.