Synthesis and Characterization of Antimicrobial Chitosan–Silver Nanocapsules for Water Purification: Removal of Bacterial Contaminants Under Laboratory Conditions

Microbial contamination of water resources remains one of the most significant environmental and public health challenges, particularly in regions with limited access to reliable disinfection technologies. This study reports the synthesis and evaluation of antimicrobial chitosan–silver nanocapsules (CS–Ag NCs) as a multifunctional platform for water decontamination under controlled laboratory conditions. Chitosan was selected as a biodegradable, cationic polymer with inherent antimicrobial activity and strong affinity for negatively charged bacterial membranes, while silver served as a broad spectrum bactericidal agent. CS–Ag NCs were prepared via ionic gelation followed by in situ silver incorporation, and subsequently characterized using FTIR, UV–Vis spectroscopy, dynamic light scattering (DLS), zeta potential measurements, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).The optimized nanocapsules exhibited a mean hydrodynamic diameter of approximately ۱۳۸ nm, a low polydispersity index of ۰.۲۳, a positive zeta potential of +۳۴.۶ mV, and an encapsulation efficiency of ۸۶%. Antibacterial activity was assessed against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) as representative waterborne pathogens. The CS–Ag NCs demonstrated strong antimicrobial performance, with minimum inhibitory concentration (MIC) values of ۱۲.۵ µg/mL for E. coli and ۲۵ µg/mL for S. aureus. Time dependent disinfection studies showed bacterial removal efficiencies exceeding ۹۹% for E. coli and ۹۸% for S. aureus within ۱۲۰ minutes. Kinetic analysis revealed that bacterial inactivation followed a pseudo first order model with high correlation coefficients (R² > ۰.۹۷).Overall, the results highlight the synergistic interaction between chitosan and silver, demonstrating that CS–Ag NCs constitute an effective and promising nanostructured disinfectant for water purification applications.

کلیدواژه ها:

Biopolymer ، nanocarriers ، Microbial ، growth ، inhibition