Amperometric Detection of Glucose Using a Conjugated Polyelectrolyte Complex with Single-Walled Carbon Nanotubes

The conjugated polymer, poly[3-(3-N,N-diethylaminopropoxy)thiophene] (PDAOT), was synthesized and employed in the supramolecular functionalization of single-walled carbon nanotubes (SWNTs). Highly stable aqueous solutions of PDAOT-SWNT complexes were obtained after sonication under mildly acidic conditions. UV-vis absorption and Raman spectroscopy studies showed that the noncovalent functionalization did not change the nanotube structure and retained its inherent properties. The reactions of [Fe(CN6)] 3-/4redox couple on Au electrodes modified with PDAOT and the PDAOT-SWNT films were studied using electrochemical impedance spectroscopy and cyclic voltammetry. A lower electron-transfer resistance and higher current response were observed on the Au/PDAOT-SWNT electrode compared with the Au/PDAOT electrode.We prepared glucose biosensors by entrapping glucose oxidase (GOx) within the PDAOT andPDAOT-SWNTfilms.Underoptimized conditions, theAu/PDAOT-SWNT/GOxbiosensor exhibited fast current response to glucose with a detection limit of 5 μM and a sensitivity of 700 ( 26 μA/mM 3 cm . The responsiveness of the Au/PDAOT-SWNT/GOx biosensor can be attributed to the synergistic effect of the high conductivity and nondenaturingmicroenvironment of the PDAOTand the large active surface area and electrical conductivity provided by the SWNTs.