Durable antimicrobial coating composition

A method of preparing a coating composition, comprising the steps of:

• providing a silver nanoparticle dispersion and chlorhexidine;
• dissolving chitosan in an acidic organic solvent to form a chitosan solution;
• incubating a chitosan cross-linker with the chitosan solution to form a solution of crosslinked chitosan;
• and
• mixing the silver nanoparticle dispersion and chlorhexidine with the solution of crosslinked chitosan to form said coating composition,
• wherein the acidic organic solvent is acetic acid and the chitosan cross-linker is glutaraldehyde;
• and
• wherein said coating composition comprises 0.0002%-0.001% w/v of silver nanoparticles, 0.48%-1.9% w/v chitosan, 0.48-1.9% v/v acetic acid, 0.05%-0.2% v/v chlorhexidine and 0.06%-0.35% glutaraldehyde v/v.