An ultra sensitive and selective impedance sensor based on protein-imprinted polymer

Abstract

By now molecularly imprinted polymers (MIPs) are still inferior to their biological rivals (antibodies etc). Here we report an MIP of polyacrylamide simultaneously showing antibody-like sensitivity and selectivity to the protein template. The MIP contains massive recognizing cavities with a powerful affinity to the protein template (bovine hemoglobin, BHb). Those cavities are surrounded by charged groups, each pairing with one of the surface charges of BHb. Hence a small piece of membrane electrode made of the MIP becomes a giant array of molecule-size capacitors. It generates an electrochemical impedance sensor to determine BHb at a wide linear range and a very low detection limit. Although a precise value has not been acquired, an affinity constant is roughly estimated close or higher compared with that of antibodies. Finally it’s testified that the electrochemical sensor can directly respond to about 90 protein molecules in a solution of 5 μL. Predictably this type of antibody-resembling MIPs is very promising to recognize and deal with charged molecules or other objects.