Amperometric immunoassay for the tumor marker neuron-specific enolase using a glassy carbon electrode modified with a nanocomposite consisting of polyresorcinol and of gold and platinum nanoparticles

A glassy carbon electrode was modified with a redox-active nanocomposite consisting of polyresorcinol, gold nanoparticles (NPs) and platinum NPs. This nanocomposite possesses the following outstanding advantages: (1) strong electrochemical signal towards H 2 O 2 at 0.92 V (vs Ag/AgCl); (2) good conductivity; and (3) ease of immobilization of antibody without the use of coupling agents. Based on these properties, a label-free amperometric immunoassay for the tumor marker neuron-specific enolase (NSE) was developed. The immunoelectrode has a linear response in the 10 pg·mL −1 to 100 ng·mL −1 NSE concentration range and a 7.8 pg·mL −1 detection limit (at an SNR of 3). The method was applied to the quantitation of NSE in human serum samples and showed satisfactory accuracy compared to an electrochemiluminescence immunoassay, a commonly used method in clinical applications. A novel multifunctional substrate was synthesized by a one-pot method using resorcinol as monomer, and HAuCl 4 and H 2 PtCl 6 as co-oxidizing agents. It was used to fabricate an ultrasensitive amperometric immunosensor for tumor biomarker.