AVS 50th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI+SS-WeA

Paper BI+SS-WeA3
Interaction of Protein Solutions with Biocompatible Organic Monolayers: An In Situ Neutron Reflectometry Study

Wednesday, November 5, 2003, 2:40 pm, Room 307

Session: Biomolecular Surface Science and Microfluidics
Presenter: R. Dahint, University of Heidelberg, Germany
Authors: R. Dahint, University of Heidelberg, Germany
D. Schwendel, University of Heidelberg, Germany
F. Schreiber, University of Oxford, UK
M. Grunze, University of Heidelberg, Germany
Correspondent: Click to Email
Oligo(ethylene glycol) (OEG) terminated self-assembled monolayers (SAMs) effectively prevent the adsorption of proteins from biological solutions. Yet, efforts are still being made to elucidate the mechanisms of protein resistance on a molecular level. For proteins deposited on the tip of an atomic force microscope (AFM), long range repulsive forces have been observed upon approaching protein resistant methoxy-terminated tri(ethylene glycol) undecanethiolate SAMs (EG3-OMe) on gold.@footnote 1@ However, as proteins adsorbed on the tip may undergo significant structural changes, it is not obvious that the same strength and type of interaction is experienced by freely moving, dissolved molecules. We, therefore, used neutron reflectometry to investigate protein/surface interactions employing biomolecules in their native state and natural environment. Room temperature measurements on protein resistant films of EG3-OMe in contact with bovine serum albumin (BSA) solutions reveal the presence of an extended protein depletion layer with a thickness of about 50 nm between the SAM and the bulk protein solution. The results are compared to the strength and range of repulsive forces measured by AFM. Temperature dependent studies on the EG3-OMe/water interface reveal, that a previously observed, density reduced water phase in the vicinity of the SAM cannot account for the protein resistant properties of the films. @FootnoteText@@footnote 1@ K. Feldman, G. Hähner, N. D. Spencer, P. Harder, M. Grunze, J. Am. Chem. Soc. 1999, 121, 10134.