Overoxidized polypyrrole incorporated with gold nanoparticles as platform for impedimetric anti-transglutaminase immunosensor

摘要

Overoxidized polypyrrole (OvoxPpy) doped with gold-nanoparticles (GNP) on a glassy carbon electrode (GCE) was used as a platform to construct a novel label-free impedimetric immunosensor for anti-transglutaminase (anti-tTG). Field emission scanning electron microscopy results confirmed the deposition of GNP with good surface coverage across the OvoxPpy substrate. The average diameter of the nanocomposite was 100 nm. The platform (GNPOvoxPpyGCE) was conductive and exhibited reversible electrochemistry (E°' = 395mV) in (pH 7.4) PBS. The electrochemical characterization of the platform was studied by cyclic voltammetry (CV) and square wave voltammetry (SWV). OvoxPpy CE had a peak separation, δE_p, value of -80mV. The GNP OvoxPpy GCE GCE showed enhanced interfacial charge transfer with δE_p, being -30mV. The SWV results corroborated CV findings which show enhanced peak current through GNP. The immunosensor was prepared by immobilizing 40 μL tTG (0.3mgmL~(-1)) onto the platform by drop coating. Electrochemical impedance spectroscopy (EIS) measurements indicated that the immunosensor system (BSATGGNPOvoxPpyGCE) markedly improved the conductivity and response of the anti-tTG immunosensor. The impedimetric immunosensor exhibited a charge transfer resistance (R_(ct))-dependent dynamic linearity of10~(-6) to 10~(-4) M for target anti-tTG (r = 0.9808), and detection limit of 5.22 x 10~(-6) M.