Surfaces having dual fibrinolytic and protein resistant properties by immobilization of lysine on polyurethane through a PEG spacer

The objective of this work is to develop a blood contacting surface that possesses both resistance to nonspecific protein adsorption and clot lysing properties. Chemical modification of a polyurethane (PU) surface with poly(ethylene glycol) (PEG); and lysine was used to create a plasminogen-binding potentially fibrinolytic surface. The preparation involves modification of the PU surface with dihydroxy PEG, reaction of the unreacted distal OH with N,N'-disuccinimidyl carbonate (DSC) to produce a PU-PEG-NHS surface, followed by conjugation of epsilon-amino-protected lysine (H-Lys(t-BOC)-OH) by reaction of the alpha-amino group with the NHS and deprotection. The result is a lysine-derivatized surface in which the epsilon-amino groups of the lysine are free to participate in binding plasminogen and tissue plasminogen activator (t-PA). Surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. Protein adsorption experiments showed that nonspecific protein adsorption was greatly reduced on these surfaces and that they adsorbed significant quantities of plasminogen from plasma. After incubation with plasma and treatment with t-PA the surfaces were able to dissolve nascent plasma clots formed around them.