I propose herein a method by which proteins may be detected and quantitated in a label-free fashion, i.e. without the need for reporter molecules. The method is based upon field-effect detection - the electrical monitoring of molecular adsorption through the measurement of the change in surface potential that results from binding of charged biomolecules to complementary sites on a sensor surface. Previously, field effect sensors have been used to detect DNA. However, detection of proteins by this method has not yet been achieved, since the size of the surface-bound receptors prevents the target proteins from approaching the sensor sufficiently closely. My proposed solution is based on the recent discovery that the organic solvent glycerol can serve as a substitute for water as a suitable medium for a variety of proteins. I propose to exploit the lower dielectric constant of glycerol compared to water's to increase the characteristic length of detection to an extent that protein sensing becomes possible. I will initially test this approach by fabricating field effect sensors for the model protein subtilisin in glycerol. If successful, l will develop arrays of such sensors for the purpose of high throughput parallel detection, and examine the generality of my results for a wide range of proteins.
