Atomic force microscopy study on the attachment of E. coli and S. aureus to a patterned surface of different materials

Many bacterial species are able to colonize the surfaces of biomedical tools or devices and form biofilms creating a source of infection and other deleterious effects. Biofilms constitute environments in which bacteria grow and are protected from the host's immune system and antimicrobial medications. The bacterial adhesion, which is an important and first step in biofilm formation, is influenced by several physico-chemical and topographical factors at the interfaces between the bacterial cell and the surface. Therefore, the mechanism of initial adhesion needs to be investigated to better understand the events of anchorage and film formation as bacteria colonise surfaces. In this work, atomic force microscopy (AFM) in the tapping mode of imaging has been employed to investigate the attachment of bacteria onto a structured surface patterned with different hydrophilic and hydrophobic areas. The interactions of Escherichia coli and Staphylococcus aureus with these structures were also monitored by fluorescence microscopy. AFM was successfully employed for the study of the cell responses to both nanotopography and the surface chemistry via observation of various cell functions; including extracellular polymeric substance (EPS) mediated cellular adhesion.