PhD Dissertation Defense

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Sanjukta Guha Thakurta

Wednesday, October 21, 2009
2:00 p.m.
Room 205 Othmer Hall

Advisor: Dr. Anu Subramanian

Design and Development of in-situ albumin binding surfaces
"Evaluation in the paradigm of blood-biomaterial compatibility"

Abstract:

Biocompatibility of natural and synthetic implant materials as blood contacting devices is crucial to host response. The aspect of hemocompatibility concentrates on minimizing thrombotic and thromboembolic response of foreign materials in contact with blood. The initial layer of surface adsorbed proteins plays a pivotal role in the adhesion and subsequent aggregation of platelets and in the activation of the coagulation cascade. Therefore, an improved surface architecture is required to gain control over the initial protein adsorption events, thereby extending the sustainability of an implantable device.

In general, surfaces with an ability to bind endogenous albumin has been known to minimize platelet adhesion and activation. While the scope of applicability is broad, in this study silicon-based surfaces were selected as model surfaces. A densely packed uniformly distributed silane monolayer was achieved on silicon based surfaces with -NH2 functionality, upon a careful optimization of hydroxylation and the subsequent silanization with 2 vol% of 3-Aminopropyltriethoxy Silane (APTES). Two linear peptides with affinity for albumin over other serum proteins were selected to create affinity surfaces. Silanized surfaces covalently immobilized with albumin binding peptides were evaluated in the paradigm of blood-biomaterial compatibility. When compared to control surfaces, albumin binding surfaces prepared in this study: (a) possessed 2.0 to 3.0 microgram/cm² of surface bound albumin with minimal surface adsorbed fibrinogen, (b) depicted low levels of adhered platelets and supported a rounded platelet morphology, (c) displayed delayed clotting, (d) showed reduced platelet adhesion and activation under shearing, and (f) exhibited faster adsorption kinetics. In conclusion, in-situ albumin binding surfaces selectively and specifically interacted with albumin without being severely displaced by other serum proteins, thereby substantiating surface passivation.