Constructing antimicrobial oil-in-water emulsions via spatially diffused ionic interlocking networks between...

A spatially dispersed ionic-interlocking network was constructed in a CHG/CMC/MCT oil-in-water nanoemulsion through multipoint electrostatic association between the multicationic biguanide groups of chlorhexidine gluconate (CHG) and the carboxylate groups of sodium carboxymethyl cellulose (CMC). Unlike conventional systems in which CHG serves solely as an antimicrobial additive, CHG functioned simultaneously as an active agent and an ionic-network-forming unit, enabling spatially distributed electrostatic interactions that stabilized the dispersed medium-chain triglyceride (MCT) droplets. The optimized CGT emulsion exhibited shear-thinning behavior and remained macroscopically stable without visible phase separation for 30 days. It also showed a distinct thermal-stability window at 60-75 °C, remained stable through eight freeze-thaw cycles, and retained good redispersibility after freeze-drying and reconstitution. CGT exhibited minimum inhibitory concentrations of 62.5 and 31.25 μg/mL against Staphylococcus aureus and Escherichia coli, respectively, and significantly inhibited Penicillium citrinum and Botrytis cinerea. At an equivalent CHG concentration of 1.95 μg/mL, incorporation into CGT increased L929 cell viability from 59.54% for free CHG to 88.80%. When applied to Gui Re Mang 82 mangoes, the optimized CGT-3 coating reduced decay incidence by 93.63% relative to the untreated control on day 12 and delayed weight loss, softening, and physicochemical deterioration without markedly interfering with normal ripening. These findings demonstrate that spatially dispersed electrostatic association can integrate emulsion stabilization, reduced CHG cytotoxicity, and sustained postharvest antimicrobial protection, providing a washable nanoemulsion coating strategy for fruit preservation.