Electrochemical nanosensors for biomolecule detection

Abstract

Sensor devices, methods and kits for detection of biomolecules are provided. According to various embodiments, the devices, methods and kits provide enhanced sensitivity through the measurement of electrochemical impedance and related properties. Certain embodiments employ nanostructured electrode elements including nanotubes, nanoparticles, nanowires, and nanocones. In a particular embodiment, single walled carbon nanotubes disposed in interconnected networks are used as electrodes. The device, methods and kits described herein have application for detection and measurement of biomolecular species including polynucleotides, proteins, polysaccharides and the like.

1 . A method of detecting the presence, concentration or amount of a biomolecular analyte species in a sample using a device or assembly comprising a first capture species immobilized relative to a base, the first capture species configured to have a binding specificity for the analyte; a working electrode disposed in communication with the base, the working electrode configured to provide effective electrical communication with a communicating aqueous fluid; and a catalyst complex including a catalyst fixed to a second capture species, the second capture species configured to have a binding specificity for the analyte, and the catalyst having an activity for a selected reporter substrate to produce a product species, the product species configured to interact with the working electrode so as to produce a detectable change in an electrical property of the working electrode, the method comprising:
 (a) exposing the immobilized first capture species to analyte species present in a sample, under condition sufficient to permit binding of the first capture species to the analyte species so as to immobilize at least some of the analyte species relative to the base;   (b) exposing the catalyst complex to the analyte species, under condition sufficient to permit binding of the second capture species to the analyte species, so as to bind the catalyst complex to at least some of the immobilized analyte species;   (c) following carrying out in any operative order the analyte-immobilization operation (a) and the catalyst-complex-binding operation (b):
 (i) removing any unbound catalyst complex; and 
 (ii) exposing the immobilized catalyst complex to the reporter substrate under condition sufficient to permit reaction of the reporter substrate with the catalyst to produce the product species; and 
   (d) making at least one electrical measurement indicating the change in charge transfer due to the interaction of the product species with the working electrode so as to detect the presence, concentration and/or amount of the analyte species in the sample.