Staphylococcus epidermidis adhesion to modified polycarbonate surfaces: gold and SAMs coated

Abstract

Bacterial adhesion to a biomaterial surface is thought to be the key step in the infection of indwelling medical devices and constitutes an object of study in the demand to reduce nosocomial infections. In this work, specific modifications on polycarbonate outer layer were utilized as model surfaces for the study of the adhesion of Staphylococcus epidermidis, one of the main microorganisms responsible for nosocomial infections. The effect of gold coating on staphylococcal adhesion was assessed, as well as of subsequent coverage with different self-assembled monolayers (SAMs): two SAMs with a methyl terminal group and hydrophobic character and two hydrophilic SAMs with a carboxylic acid terminal group. Variations in the aliphatic chain length were also tested. A SAM with a calix-crown molecule was also created to immobilize a specific protein and its antibody. The extent of staphylococcal adhesion to methyl terminated SAMS was reduced compared to the number of cells adhered to the carboxyl acid terminated SAMs, demonstrating that methyl terminated SAMs constituted more suitable surfaces in preventing bacterial adhesion. The calixcrown molecule favours high levels of adhesion due to its non-specific bonding nature and geometrical configuration. However, when a specific protein is linked to calix-crown, bacterial adhesion occurs to a much lower extent. The results obtained in this work have a potential practical significance showing that the use of certain SAMs as surface modifiers may constitute a successful method in the reduction of bacterial adhesion to biomedical surfaces.