Effects of controlled fibronectin surface orientation on subsequent Staphylococcus epidermidis adhesion.

Abstract

Several bacterial species, including Staphylococcus aureus and Staphylococcus epidermidis (SE) are known to express cell receptors that bind specifically to surface immobilized or extracellular matrix ligands, such as the protein fibronectin (FN). Yet, few existing studies have examined the effect of protein surface orientation on bacterial adhesion. We report here a substratum modification protocol that allows for the specific orientation of FN molecules on a surface at known levels of surface coverage. Monoclonal antibodies (Mabs), specific to either the COOH-terminus or NH3-terminus of FN, are conjugated to biotin, then immobilized to streptavidin-coated glass substrata. Specific orientation of the bound FN molecules is verified using the same Mabs in an ELISA. Bacterial adhesion of Staphylococcus epidermidis (SE) to FN bound by either its C-terminus or its NH3-terminus was quantified in batch static adhesion assays. Results indicate an increase in SE adhesion to FN-coated surfaces when the FN is bound by its C-terminus (NH3-terminus free), indicating SE receptor-specific adhesion to the FN NH3-terminus. These studies demonstrate that antifibronectin monoclonal antibodies can be used to specifically bind and orient fibronectin on a surface. In addition, adhesion of SE to these model substrata can be controlled by the orientation of the protein.