Electrochemical Detection of Peroxynitrite Using a Biosensor Based on a Conducting Polymer-Manganese Ion Complex

A peroxynitrite (ONOO-) biosensor has been developed through the preparation of a new manganese [poly-2,5-di-(2-thienyl)-1H-pyrrole)-1-(p-benzoicacid)](Mn-pDPB) complex. DPB monomer was first synthesized and polymerized for the purpose of providing a polymer backbone for complex formation with Mn2+ ion. The Mn-pDPB complex was characterized via Magnetomotive Force (MMF) simulation, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. The complex selectively enhanced the reduction process of ONOO- which was used as the analytical signal for chronoamperometric detection. A polyethyleneimmine (PEI) layer was coated on the complex surface to increase selectivity and stability. The chronoamperometric calibration plot showed the hydrodynamic range of 2.0 x 10(-8)-5.0 x 10(-7) M. The detection limit was determined to be 1.9 (+/- 0.2) x 10(-9) M based on S/N = 3. The microbiosensor, fabricated on a 100 mu m diameter Pt tip, was applied in a real rat plasma sample for the detection of spiked concentrations of ONOO-. The reliability and long-term stability of the microbiosensor was also examined with YPEN-1 cells in vitro, and the results shown were promising.