Synthesis and characterization of biodegradable antimicrobial chitosan coatings with added silver and copper nanoparticles for biomedical applications

One of the most important reasons for the removal of biomaterials and implanted medical devices is post-surgical infection. Such complications cause an increase in morbidity and mortality rates worldwide, as well as having a strong economic impact, especially in countries with low budgets.

A measure to face this health problem consists of the design of antimicrobial coatings that fulfill two key functions: they must gradually release antimicrobial compounds while in the tissue environment and biodegrade over time. In this work, these needs were considered, and chitosan films were formulated with antimicrobial metal nanoparticles.

The antimicrobial activity of the films was tested against Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii. Inhibition achieved against C. albicans was 100% in both treatments; in the case of S.aureus, it was 77% in AgNP films and 93% in CuNP films; P. aeruginosa inhibition was 89% in AgNP films and 97% in CuNP films; finally, the inhibition of A. baumannii was 77% in AgNP films and 93% in CuNP films. A possible explanation for the higher antimicrobial activity of the CuNP filmscould be the fact that these films degraded over a 24-hour period, releasing the antimicrobial agent faster, while silver films remained intact. The proposed hypothesis is that microbial enzymes that degrade high-molecular-weight carbohydrates are dependent on the copper. This result can be very useful for the design of coatings whose rate of biodegradation can be controlled and whose antimicrobial activity increases in the presence of pathogens.

In the future, a burn or subcutaneous implant model will be used to evaluate the biocompatibility of chitosan films with nanoparticles. These models will help assess tissue response, healing effects, and potential toxicity, ensuring that the materials are safe and effective for biomedical applications.