AVS 47th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeP

Paper BI-WeP16
A Novel Approach to Studying Structures and Orientation at the Protein-Self Assembled Monolayer Interface

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: L.F. Pardo, Clemson University
Authors: L.F. Pardo, Clemson University
T. Boland, Clemson University
Correspondent: Click to Email
Self-assembled monolayers (SAMs) have become an important tool in protein adsorption studies, partly because they represent chemically, well-defined model systems. However, specifics on how the structure and orientation of both the SAM and protein change during adsorption in situ remain unknown. The purpose of this study is to quantify these changes via analysis of protein adsorption onto SAMs by a novel technique using Evanescence Reflection Spectroscopy (ERS). This technique allows in situ characterization of the surface chemistry, providing quantitative information on structure and orientation at the interface only. In this study, model proteins, (polyserine and fibrinogen) were adsorbed onto, -OH, -COOH, and CH3 terminated SAMs of hexadecanethiols on gold. The surfaces were then characterized by FTIR and ellipsomentry. The IR measurements reveal significant differences were between protein structures in dry and wet states. The spectra of polyserine in the dry state show only amide II stretch (1507 cm-1) while the amide I stretch is absent implying that the polyserine lies flat on the SAM surface. Analysis of the IR spectra measured in PBS solution depicting peaks in the Amide I and II regions showed that polyserine extends away from the surface under aqueous conditions. Furthermore, information on the secondary structure of the solvated proteins adsorbed to the various SAMs was attained. The resulting of protein-SAM interfaces are dynamic and will undergo structural changes, desorption or surface reactions. The structural characterization of protein SAM interactions will be helpful when designing templates for tissue engineering applications.