AVS 49th International Symposium
    Biomaterials Tuesday Sessions
       Session BI+SS-TuA

Paper BI+SS-TuA7
Novel Immunosensor Interfaces based on Mixed Self-Assembled Monolayers of Thiols on Gold

Tuesday, November 5, 2002, 4:00 pm, Room C-201

Session: Molecular Recognition Surfaces
Presenter: F. Frederix, IMEC, Belgium
Authors: F. Frederix, IMEC, Belgium
M. Boesmans, IMEC, Belgium
K. Bonroy, IMEC, Belgium
W. Laureyn, IMEC, Belgium
A. Campitelli, IMEC, Belgium
M.A. Abramov, KULeuven, Belgium
W. Dehaen, KULeuven, Belgium
G. Maes, KULeuven, Belgium
Correspondent: Click to Email
The two components that make up a biosensor are the biological recognition layer, which selectively binds the analyte, and the transducer which translates this recognition event into an electrical signal. The increasing miniaturization of biosensor transducers (and thus of their active areas) and the demand for sensitivity, require a fully evaluated and optimized covalent immobilization of antibodies. Our research is therefore not only focusing on the transducer but also on the biological interface. This biological recognition layer mainly determines the specificity, stability, reproducibility, and durability of the biosensor as a whole. Our strategy is to achieve the above-mentioned properties based on mixed Self-Assembled Monolayers on gold. The realization of a biological recognition interface encompasses various aspects. Cleanliness and structural properties of the gold surface are very important for perfect SAM formation and were therefore optimized. Novel thiols able to couple antibodies or to mitigate non-specific adsorption were synthesized and evaluated, along with new molecules for blocking. The mixed monolayer formation of these novel thiols was characterized using contact angle measurements, XPS, cyclic voltammetry, and GA-FTIR. The immobilization of proteins on mixed SAMs is the most important step in the realization of immunosensors because it determines the activity of the antibodies and therefore the sensitivity. Random and orientated immobilizations of (chemically modified) antibodies on mixed monolayers of thiols were compared using Surface Plasmon Resonance. The enhanced sensitivity (< 0,1 ng/mL) and selectivity (no non-specific adsorption) were compared to commercially available biological recognition layers. In summary, we will show the importance of the biological recognition layer for the global performance of a biosensor and how the sensitivity can be drastically enhanced by modifications on the biological interface of an immunosensor.