Modification of poly(dimethyl siloxane) surfaces with an antibacterial claramine-derivative through click-chemistry grafting

Poly(dimethyl siloxane) (PDMS) is one of the most widely used materials in the biomedical field, but due to its hydrophobic character it is prone to bacterial adhesion and biofilm formation. Prevention of bacterial adhesion by contact-killing surface is one of the promising strategies, although bacterial resistance to conventional active molecules complicates antibacterial control. A prepared PDMS surface with alkyne groups was covalently grafted with an azidated claramine-derivative, through the simple and orthogonal CuI-catalyzed Huisgen 1,3-dipolar click cycloaddition. The azidated claramine derivative was prepared in a four-step synthesis pathway from deoxycholic acid. The alkyne groups were introduced onto the PDMS surface via a silanization reaction. X-Ray Photolectron Spectroscopy (XPS) analysis has demonstrated the covalent grafting of the claramine with a total conversion of the azide group into a triazole ring. Fluorescent microscopy has showed an antibacterial activity of the modified surface against both Gram – (Escherichia coli) and Gram + (Staphyloccocus epidermidis) bacteria, which could be derived from electrostatic attraction followed by a membrane destabilization. These results confirmed the importance of using a chemioselective reaction to control the orientation of covalently immobilized antibacterial molecules in order to keep their activity. PDMS surfaces based on claramine-derivative can be potentially useful for the elaboration of biomaterials preventing biofilm formation and addressing the issue of antibacterial resistance.