Poly(pyrrole) versus poly(3,4-ethylenedioxythiophene): implications for biosensor applications

The stability of poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(pyrrole) was investigated as the electroactive component in amperometric biosensors. PEDOT and poly(pyrrole) were synthesized chemically inside the pores of a track-etch membrane by immersing the membrane into a solution of the corresponding monomer and ferric chloride. This paper reports the detailed results on the stability of poly(pyrrole)- and PEDOT-coated track-etch membranes under physiological relevant conditions by means of amperometric and resistance measurements, FT-IR spectroscopy, ESR spectroscopy and scanning electron microscopy. The experiments demonstrated that poly(pyrrole) could only be used as an electroactive component in (bio)sensing for a very short period of time. In poly(3,4-ethylenedioxythiophene) an attractive candidate is found to replace poly(pyrrole) for continuous sensor applications, since its electrochemical stability is superior compared to the latter one.