AVS 50th International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoM

Paper BI-MoM6
A Comparison of Microcontact Printed and Solution Adsorbed Cytochrome c Protein Films on Indium Tin Oxide Electrodes

Monday, November 3, 2003, 10:00 am, Room 307

Session: Protein-Surface Interactions
Presenter: A. Runge, University of Arizona
Authors: A. Runge, University of Arizona
S. Saavedra, University of Arizona
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The immobilization of proteins on a surface in a controlled way that retains their function is one of the challenges in making a functioning biosensor. Electrochemical biosensors use redox active proteins to impart selectivity to the electrode surface on which they are immobilized (either adsorbed or covalently attached). The orientation of proteins on the surface is presumed to be important for proper functioning of the device. We are investigating using microcontact printing as a way of immobilizing cytochrome c onto indium tin oxide electrodes in order to determine how the method of immobilization affects the orientation and function of the protein. We are presenting the results of three different methods for forming protein films on indium tin oxide that have been characterized and compared using cyclic voltammetry and X-ray photoelectron spectroscopy. Preliminary results from surface sensitive polarized spectroscopic studies will also be discussed. Protein films formed by adsorption of cytochrome c out of solution and by microcontact printing with both hydrophobic and hydrophilic PDMS are compared in terms of total and electrochemical surface coverage, standard reduction potential and rate of electron transfer with the ITO surface. Plasma treatment of the PDMS stamps, which makes them hydrophilic, dramatically increases the surface coverage of printed films to the level of solution adsorbed films. We have demonstrated that a redox active protein can be microcontact printed onto an electrode surface with its capability for direct electron transfer with the surface intact. The total surface coverage of the different films were compared using X-ray photoelectron spectroscopy.