Green‐Synthesized Metal Nanoparticles Coated With Chitosan: Enhanced Stability and Antimicrobial Potential Against ESKAPE Pathogens

The global challenge of multidrug resistance and the rapid spread of ESKAPE bacteria necessitate the urgent development of safe and effective antimicrobial agents. Metal nanoparticles (MNPs) offer promise due to their unique properties but are hindered by challenges, such as agglomeration, which reduces their stability and efficacy. Surface coating with chitosan is a promising solution that synergistically enhances stability and antimicrobial activity. This study explored the green synthesis of silver (Ag), gold (Au), zinc oxide (ZnO), and copper (Cu) nanoparticles using Cyperus rotundus extract, followed by surface coating with chitosan, to assess improvements in stability and antimicrobial activity against two representative ESKAPE bacteria-Pseudomonas aeruginosa and Staphylococcus aureus. The results varied, with chitosan affecting the agglomeration and stability of each metal differently. Although agglomeration significantly influenced stability, it did not strongly affect antimicrobial activity. This study highlights that preventing agglomeration is crucial for ensuring the stability of MNPs, and chitosan coating plays a critical role in preventing agglomeration and enhancing nanoparticle stability without necessarily dictating antimicrobial efficacy. Importantly, CH@AgNPs show significant potential as an alternative to antibiotics against multidrug-resistant ESKAPE pathogens, supporting their further development for pharmaceutical applications.