In-situ growth of Ag nanoparticles embedded in chitosan coating for potent antimicrobial activity

Abstract

Developing highly antimicrobial coatings is an important strategy to control the risk of pathogen colonization and biofilm formation, especially in indwelling and implantable medical devices. This work presents a facile and practical approach to preparing potent antimicrobial coatings based on the chitosan-silver composite. The synthesis is conducted by simply stirring a chitosan (CS) solution with different amounts of silver (Ag) at room temperature, and the composite is applied as a coating on a polystyrene (PS) surface. In-situ reduction of Ag+ ions to metallic Ag (Ag°) during the coating process leads to silver nanoparticles (AgNPs) forming into Ag rods half-embedded into the chitosan film and half-exposed on the coating surface. This distinctive structure promotes effective antibacterial action through the Ag+ release and photocatalytic activity of AgNPs. The coatings exhibit potent antimicrobial activity with 99.89 % efficiency against Escherichia coli after 90 minutes and 100 % against Staphylococcus epidermidis after 30 minutes under LED light irradiation. These coatings also display high stability with an insignificant decrease in the antibacterial activity after three times of reutilization. The newly synthesized formulations can be considered a promising alternative for antimicrobial coatings to avoid biofilm formation and for coating materials with various applications, especially in the biomedical field.