(201d) Analysis of Platelet Adhesion to in-Situ Albumin-Binding Surfaces Under Defined Shear Conditions

The adhesion of platelets to in-situ albumin binding surfaces was evaluated under flow. Briefly, in-situ albumin binding surfaces were prepared by derivatization of organosilane-grafted silicon surfaces with a linear peptide that was shown to selectively and specifically interact with human serum albumin over other serum proteins. Unmodified surfaces served as controls. The albumin binding affinity of surfaces prepared was first evaluated by exposing the surfaces to platelet poor plasma. Independent experiments were carried out at the following shear rates, 96 sec-1 and 320 sec-1, respectively, in a GlycotechTM circular chamber. Under the conditions evaluated, peptide functionalized surfaces were noted to preferentially bind human albumin (1200-1500 ng/cm2) with trace amounts of fibrinogen. In contrast unmodified control surfaces were noted to bind comparable amounts of albumin and fibrinogen. The adhesive response of platelets to the peptide functionalized surfaces under similar flow conditions was also evaluated. Under conditions of shear, rounded, disc-shaped platelet morphology was noted on peptide functionalized surfaces, whereas a spread-out morphology was observed on control surfaces, which had a higher level of adsorbed fibrinogen. The higher adsorption of albumin on peptide functionalized surfaces was observed to correlate with the platelet response on the surfaces evaluated.