Biosensors are powerful tools aimed at providing selective identification of target compounds at ultratrace levels. The extremely high sensitivity and selectivity of biological recognition, combined with the nano-scale dimensions of electronic devices offers the potential for major improvements in the detection performance and requires the integration of many expertises including biotechnology, nanotechnology, electro-optics, and surface chemistry. In this proposal, the detection and identification of adsorbed proteins at the interface using surface modified nanogap capacitors as promising biosensors is described. Protein adsorption induces substantial changes in many physical properties at the interfacial regime, including the dielectric constant. By measuring frequency-dependent capacitance change, dielectric spectroscopy has been used to monitor fast and in situ biological recognition events such as antigen antibody complex formation at interfaces. Although it is a promising technique used in biosensor development, current dielectric spectroscopy is limited in terms of sensitivity and reproducibility due to the difficulty in reproducing ultra-narrow electrode gaps by mechanical methods. Recent advancements in silicon-based lithographic techniques, however, have allowed us to produce nano-scale devices with uniform and narrow gap sizes that improve the sensitivity and reproducibility of conventional capacitance measurements. Nanogap capacitors produced in this fashion will be used to detect selective identification of target compounds by monitoring changes in frequency-dependent capacitance. The experimental results obtained from capacitance measurements will be compared with the data derived from complementary surface analysis experiments under the identical adsorption conditions. This proposal not only describes our frontier proof-of-concept plan to use electronic devices produced by nanotechnology, but also provide a good example of how nanotechnology can be combined with biotechnology, and surface chemistry to overcome limitations encountered in conventional detection technology with the ultimate goal of aiding biosensor development.
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