AVS 46th International Symposium
    Biomaterial Interfaces Group Monday Sessions
       Session BI-MoA

Paper BI-MoA6
Protein Resistant Surfaces Based on Reactions of Thiol-Terminated Polyethylene Oxides with Gold

Monday, October 25, 1999, 3:40 pm, Room 613/614

Session: Protein Solid-Surface Interactions I
Presenter: J.L. Brash, McMaster University, Canada
Authors: J.L. Brash, McMaster University, Canada
Y.J. Du, McMaster University, Canada
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Gold is a relatively inert metal but has strong specific interactions with sulfur functions, particularly thiol. Thiols that contain bioinert or bioactive moieties (eg bioactive peptides containing a terminal cysteine) can thus be chemisorbed to gold films to provide correspondingly bioinert or bioactive surfaces. High surface densities of ligands should be possible due to the abundance of thiol binding sites in the surface. Thiolated gold surfaces thus have great potential in the design of biocompatible materials. We have used this approach in the development of a variety of surfaces based on:(1) suppression of non-specific protein adsorption, (2) selective/exclusive adsorption of a target protein from the contacting biological fluid. In the present work, surfaces have been developed consisting of HS-polyethylene oxides (HS-PEO, expected to minimize non-specific protein adsorption) chemisorbed to gold films deposited on polyurethane or silicon. PEOs of varying MW and architecture (linear, star) were reacted with mercaptoacetic acid to attach terminal thiol groups. HS-polypropylene oxides (HS-PPO) were used as controls, not expected to reduce protein adsorption. Chemisorption of the PEOs and PPOs to gold was verified by XPS. The adsorption of fibrinogen and albumin from buffer and plasma was studied by radioiodination methods. It was found that: (a) protein adsorption is low on all the modified surfaces and decreases with increasing molecular weight of the PEO, (b) with MeO as the terminal group at the free end of PEO, the suppression of protein adsorption is less than when OH is the terminal group, (c) chemisorbed PPO suppresses the adsorption of fibrinogen and albumin but not as effectively as PEO. In ongoing work we are investigating surfaces with heparin attached to the free chain end of chemisorbed PEO.