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

Paper BI-MoA7
Protein Adsorption on Mixed Polyethylene Glycol/Methyl Terminated Alkane Thiol Self-Assembled Monolayers

Monday, October 25, 1999, 4:00 pm, Room 613/614

Session: Protein Solid-Surface Interactions I
Presenter: T. Kim, University of Washington
Authors: T. Kim, University of Washington
K.D. Hauch, University of Washington
J.W. Rogers, Jr., University of Washington
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Polyethylene glycol(PEG) functionality has been used in many settings to resist protein adsorption.@footnote 1@ In this work, PEG and methyl terminated alkane thiols were used to form mixed self-assembled monolayers(SAM) on gold.@footnote 2@ These surfaces were used to study fibrinogen(Fg) adsorption. The molar percent of PEG thiol in the assembly solution was varied from 0-100% to vary the amount of PEG thiol on the surface. The mixed SAM's were examined with XPS. The atomic composition of the surfaces assembled from pure methyl thiol and pure PEG thiol agreed with expected values. An increase in ether bonds was seen as the PEG thiol ratio in the assembly solution was increased indicating an increase of PEG thiol in the mixed monolayer. The adsorption of I-125 labeled human Fg from dilute plasma (2 hr, 37 degrees Celsius) was measured. Fg adsorption on the SAM's ranged from 11-70 ng/cm^2, significantly lower than the control, polytetrafluorinated ethylene. The pure PEG thiol monolayer adsorbed 12 times less Fg than the control and 7 times less than the pure methyl SAM. We have demonstrated that the surface composition of the SAM is influenced by the composition of the assembly solution. Increased PEG thiol in the SAM reduced Fg adsorption with the pure PEG monolayer exhibiting the lowest values. Future work will include further surface characterization of the SAM's, adsorption studies with other proteins, and examination of choline or saccharide terminated thiols. @FootnoteText@ @footnote 1@ Lopez, G.P., et. al. Glow discharge plasma deposition of tetraethylene glycol dimethyl ether for fouling-resistant biomaterial surfaces. J. Biomed. Mater. Res. 1992, 26, 415-439 @footnote 2@ Ulman, A. Formation and Structure of Self-Assembled Monolayers, Chem. Rev. 1996, 96, 1533-1554