Improved electrochemical immunosensor for myeloperoxidase in human serum based on nanogold/cerium dioxide-BMIMPF6/l-Cysteine composite film

An electrochemical immunosensing assay for myeloperoxidase (MPO) determination in human serum has been developed. Firstly, l-Cysteine was initially electropolymerized on an Au electrode to form l-Cysteine film. After that cerium dioxide (CeO2) dispersed in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) were immobilized on the l-Cysteine film. Then the negatively charged nanogold particles were adsorbed onto the membrane via the positive charge of CeO2, which aimed at assembling more antibody of MPO (anti-MPO). The resulting immunosensor showed a high sensitivity, broad linear response to the MPO concentration comprised between 10 ng/mL and 400 ng/mL with a detection limit of 0.06 ng/mL. Moreover, the surface morphology of the electrode was studied by means of a scanning electron microscope and the electrochemical properties of the fabricated immunosensor were further characterized by cyclic voltammetry. Also, factors influencing the performance of the resulting immunosensors were studied in detail.