Radio-analytical determination of the coating efficiency of cyclic RGD peptides

Coating of artificial surfaces with RGD (= arginine-glycine-aspartate) peptides to enhance cell adhesion is an ongoing issue. Thereby, the physiological adhesion process to the extra-cellular matrix (ECM) is mimicked by the peptide coating, leading to a strong cell-surface contact, followed by spreading and proliferation of the cells. For comparable cell adhesion studies, it is important to know the density of the RGD peptides on the surface. Here, we present an approach to determine the amount of bound cyclic RGD peptide by radio labeling with I-125 of a tyrosine-containing RGD peptide on different materials surfaces (poly(methyl methacrylate) (PMMA), titanium, and silicon). For all surfaces, the amount of bound peptides is in the range of pmol/cm(2).