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

Abstract

Abstract 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 149.4 nm, PDI 0.26, and zeta potential + 12.0 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.