Chitosan coating fabricated through nanotopography and alkylation for the prevention of bacterial attachment and corrosion

Abstract

Although metallic materials are widely used in biomedical devices, most of them have no antibacterial property and exhibit corrosion-related problems in physiological environments. This study aimed to develop a biocide-free chitosan coating to inhibit bacterial adhesion and corrosion. First, a chitosan coating fabricated through nanotopography was formed on the surface of carbon steel by using soft imprinting technology. Next, hexanal was grafted onto the chitosan by using a Schiff base reaction. Nanomorphological assessments using scanning electron microscopy, confocal laser scanning microscopy, and cross-sectional transmission electron microscopy confirmed a concave width, depth, and bottom thickness of approximately 666, 242, and 208 nm, respectively. Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed that hexanal was successfully grafted to chitosan. Finally, the surface hydrophobic properties, antibacterial adhesion, and electrochemical corrosion resistance of chitosan coatings with and without nanopatterning and hexanal grafting were investigated. The results indicated that the hydrophobic angle of chitosan with both nanopatterning and hexanal grafting exceeded 120° and that the hysteresis angle was only 20°, which may help inhibit the attachment of Staphylococcus aureus and Escherichia coli. During an electrochemical corrosion test, chitosan with both nanopatterning and hexanal grafting exhibited the highest corrosion potential and the lowest corrosion current density, indicating improved corrosion resistance. These results suggest that imparting nanopatterning and alkylation properties to chitosan solves not only the problem of bacterial attachment to bare metal substrates but also the problem of corrosion.