FUNCTIONAL-CHARACTERIZATION OF A CONDUCTING POLYMER-BASED IMMUNOASSAYSYSTEM

Experiments have been performed to characterize the electrical propert ies and functionality of a poly(3-hexylthiophene)-coated platinum elec trode developed as a sensor for immunoassay read-out. Admittance measu rements were performed on the coated electrodes as a function of frequ ency. The admittance spectra obtained show that the sensor is capaciti ve in nature. A circuit model is presented for comparison to other con ducting polymer systems. Dynamic sensor response is characterized by o xidizing the polymer via a hydrogen peroxide-iodide pathway. Hydrogen peroxide is introduced either by direct injection or through a glucose -glucose oxidase reaction to determine electrode functionality and sen sitivity. Sensor response to chemical oxidation is measured as a funct ion of frequency and applied signal amplitude. System response is line ar in frequency from 1 Hz to 70 Hz and in excitation amplitude up to a pproximately 600 mV. System sensitivity is analyzed based on oxidant g eneration from the enzyme-initiated pathway, sensor baseline drift, an d the noise band on the quiescent sensor current. (C) 1998 Elsevier Sc ience S.A. Published by Elsevier Science S.A.