IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Friday Sessions
       Session BI-FrM

Paper BI-FrM10
An Electroactive Substrate for Direct Transduction of Biorecognition

Friday, November 2, 2001, 11:20 am, Room 102

Session: Biosensors
Presenter: J. Yan, The University of New Mexico
Authors: J. Yan, The University of New Mexico
P. Hampton, The University of New Mexico
G. López, The University of New Mexico
Correspondent: Click to Email
Direct electrochemical transduction of biorecognition on well-defined and protein-resistant electrode surfaces has recently attracted enormous attention. Herein, we report the design and characterization of self-assembled monolayers (SAMs) presenting protein binding ligands, electroactive probe molecules and protein-resistant oligo(ethylene glycol) moieties that allow direct electrochemical transduction of biorecognition at modified electrodes. The electroactive compound, N-(11-mercaptoundecyl)-N'-carboxymethyl-4,4'-bipyridinium dibromide (1), was selected and synthesized because of the known environmental sensitivity and reversibility of the redox chemistry of the viologen groups (i.e., 4,4'-bipyridyl dications) and potential to derivatize the acid terminus with biological molecules. Mixed SAMs of compound 1 and (1-mercaptoundec-11-yl)tri(ethylene glycol) (2) on gold were prepared by coadsorption from a solution of 1 and 2 (@chi@@sub 2@ = 0.6). N-(5-aminopentyl)biotinamide was subsequently attached to the surface through amide bonds. Cyclic voltammetric, ellipsometric and X-ray photoelectron spectroscopic measurements confirmed the attachment of the biotin ligands and the efficiency of the SAM in preventing nonspecific protein binding. Incubation of the biotin-modified SAM in a phosphate buffered saline (PBS, pH 7.4) containing 30 µg/ml anti-biotin for 2 h resulted in a significant negative shift in the redox potential of viologen moieties and a decrease in the peak currents and the charging currents. Incubation of the biotin-modified SAM in PBS containing biotin-blocked anti-biotin for 2 h, however, showed no change in the redox potential, peak currents and charging currents, indicating that the adsorption was biospecific.