Novel gold-decorated polyaniline derivatives as redox-active species for simultaneous detection of three biomarkers of lung cancer

Two kinds of novel redox-active species, gold-decorated polyaniline derivatives (Au-PANI derivatives) including gold-poly(o-aminophenol) (Au-PoAP) and gold-poly(p-phenylenediamine) (Au-PpPD), which can produce oxidation peaks at -0.2 V and 0.25 V, respectively, were synthesized by a one-pot method using o-aminophenol and p-phenylenediamine as monomers, and chloroauric acid as the oxidant. The gold nanoparticles in the composite make a prominent contribution to its conductivity. These two Au-PANI derivatives together with gold-poly(o-phenylenediamine) (Au-PoPD, oxidation peaks at -0.5 V) were used as redox-active species for simultaneous electrochemical detection of three biomarkers, namely carcinoembryonic antigen (CEA), cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) and neuron-specific enolase (NSE), which are typical biomarkers of lung cancer. The present immunosensor exhibited a wide linearity range of 0.01 to 100 ng mL(-1) and limits of detection 6.3 pg mL(-1) for CEA, 8.5 pg mL(-1) for CYFRA21-1 and 7.9 pg mL(-1) for NSE. In addition, for the clinical serum sample, the data from this immunosensor are consistent with those from enzyme-linked immunosorbent assay (ELISA).