Protein binding on thermally grown silicon dioxide

Proteins can confer functional properties to micro- or nanodevices or can passivate microdevice surfaces. We investigated the binding behavior, structure, and activity of a model protein (streptavidin) bound to thermally grown silicon dioxide, a substrate chosen for its prevalence in microfabricated devices. Multiple binding techniques (direct adsorption, substrate nanometer-scale patterning, and chemical conjugation) were investigated. Atomic force microscopy (AFM) images of surfaces prepared using these methods revealed differential morphological differences in proteins bound using each method. AFM adhesion measurements with protein-functionalized tips also showed a variation in adhesion strength between the techniques that was further supported by fluorescence imaging and biological assay. We show that nanometer-scale patterning and chemical conjugation both improve protein binding to the surface compared to direct adsorption. These techniques provide methods for directed attachment of proteins to biomedical devices. (c) 2005 American Vacuum Society.