Human serum albumin and fibrinogen interactions with an adsorbed RGD-containing peptide

The modification of polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE) with an arginine-glycine-aspartic acid cell adhesion peptide, RGD peptide (PepTite Adhesive Coating; Telios Pharmaceuticals, San Diego, CA) has been previously investigated. Initial animal studies showed this RGD peptide to accelerate healing and assist in the formation of an endothelial cell lining of the lumenal side of PET and PTFE fabrics in a cardiovascular application. It is of interest to determine how this RGD peptide is able to influence cellular events through intervening layers of plasma proteins that spontaneously adsorb upon implantation. This study examined the interaction of predeposited RGD-containing peptide with human serum albumin (HSA) or fibrinogen that was characterized using multiple attenuated internal reflection infrared (MAIR-IR) spectroscopy, ellipsometry, and contact angle analysis. It was determined that fibrinogen-containing films consistently exhibited more mass than films of the RGD peptide, HSA, or HSA adsorbed onto RGD peptide-containing films. MAIR-IR spectra of RGD peptide films before and after HSA adsorption were similar in absorption and intensity; however, ellipsometry indicated HSA introduction had created thicker, less dense films. Fibrinogen, on the other hand, when adsorbed onto RGD peptide films provided increased relative mass in a more compact arrangement. Contact angle analyses of each of the dried films showed their surface energies to remain high, but the polar components of RGD peptide films were reduced after either serum protein adsorption. These phenomena may be related to the minimal thrombus accumulation that was noted during the initial animal studies, that promoted subsequent healing.