A Novel Approach to Combating Antibiotic Resistance: A Chitosan-Based Nanocomposite with Green AgNPs and Gentamicin

This study investigates the synthesis of silver nanoparticles (AgNPs) using <i>Crassula ovata</i> (Jade plant) leaf extract and their subsequent incorporation into chitosan-based nanocomposite films for enhanced antimicrobial activity against four pathogenic microorganisms: <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, <i>Staphylococcus epidermidis</i>, and Methicillin-resistant <i>Staphylococcus aureus</i>. Jade AgNPs were chosen for their ease of synthesis, stability, and potent antimicrobial activity. Chitosan encapsulation improved the stability of AgNPs and enhanced their interaction with bacterial cells, leading to improved bactericidal performance. The addition of gentamicin to the nanocomposite further amplified antibacterial activity, reducing the MBC values from 10 to 4 µg/mL for <i>E. coli</i>, 12.5 to 6 µg/mL for <i>P. aeruginosa</i>, 10 to 6 µg/mL for <i>S. epidermidis</i>, and 15 to 8 µg/mL for MRSA, compared to AgNPs alone. Mechanical characterization using dynamic mechanical analysis revealed improved robustness, with storage modulus increasing from approximately 24 MPa for chitosan-AgNPs films to 36 MPa for gentamicin-loaded nanocomposite films, while maintaining elasticity. Overall, these multifunctional nanocomposite films demonstrate strong antimicrobial activity and improved mechanical performance, supporting further evaluation as candidate materials for wound-related antimicrobial applications and localized infection control strategies. Such localized antimicrobial platforms may also contribute to strategies aimed at mitigating antibiotic resistance.