Synergistic Antimicrobial Activity of a Nanopillar Surface on a Chitosan Hydrogel

Despite ongoing efforts and technology development, the contamination of medical device surfaces by disease-causing microbes remains problematic. Two approaches to producing antimicrobial surfaces are using antimicrobial materials and applying physical topography such as nanopatterns. In this work, we describe the use of physical topography on a soft hydrogel to control microbial growth. We demonstrate this approach by using chitosan hydrogel films with nanopillars having periodicities ranging from 300 to 500 nm. The flat hydrophilic chitosan films exhibit antimicrobial activity against the pathogenic bacteria Pseudomonas aeruginosa and filamentous fungi Fusarium oxysporum. The addition of nanopillars to the hydrogel surface further reduces the growth of P. aeruginosa and F. oxysporum up to ∼52 and ∼99%, respectively. Multiple modes of antimicrobial action appear to act synergistically to inhibit microbial growth on the nanopillar hydrogels. We verified that the strongly bactericidal and fungicidal nanopillared material retains biocompatibility to human epithelial cells with the MTT assay. The nanopillared material is a promising candidate for applications that require a biocompatible and antimicrobial film. The study demonstrates that taking advantage of multiple modes of antimicrobial action can effectively inhibit pathogenic microbial growth.