Influence of Fibrinogen on Staphylococcus epidermidis Adhesion Can Be Reversed by Tuning Surface Nanotopography

Surface modifications in the nanoscale regime have shown promising potential in the combat against bacterial adhesion and colonization of surfaces. However, detailed knowledge of how the bacteria-substrate interactions occur is still limited. Herein we have used a gradient in nanostructure density on a surface, realized by immobilizing 40 nm sized silicon dioxide nanoparticles with increasing distance on a glass surface, to systematically study the initial attachment of Staphylococcus epidermidis with or without the presence of human fibrinogen. By using a parallel plate laminar flow chamber, we found a near-linear positive correlation between the adhesion of S. epidermidis with increasing nanoparticle density on unmodified (hydrophilic) nanogradients as well as on gradients where polyethylene glycol was immobilized on the surface in-between nanoparticles. However, if the nanostructured gradient was precoated with human fibrinogen the opposite relationship was observed, although the adsorbed amount of fibrinogen was found to be higher on nanostructured than on smooth surfaces. Our results highlight that even minute changes of the nanotopography on a surface can have profound impact on initial attachment of S. epidermidis to biomaterial surfaces and that the presence of nanostructures strongly hampered the cell's ability to bind to adsorbed fibrinogen, possibly due to changes in the orientation or secondary structure of the fibrinogen molecule upon adsorption.