Electrochemical immunoassay for the cancer marker LMP-1 (Epstein-Barr virus-derived latent membrane protein 1) using a glassy carbon electrode modified with Pd@Pt nanoparticles and a nanocomposite consisting of graphene sheets and MWCNTs

Abstract

We describe an electrochemical sandwich immunosensor with enhanced sensitivity for the determination of the tumor marker LMP-1. The capture antibody (Ab1) was immobilized on a composite consisting of graphene sheets and carboxylated multiwalled carbon nanotubes (GS-MWCNTs) in a chitosan matrix that was placed on the surface of glassy carbon electrodes (GCE). The detection antibody (Ab2) marked with thionine was fixed on a composite of HRP/Pd@Pt-MWCNTs. Following exposure to the antigen (LMP-1), an amplified signal was observed in differential pulse voltammetry because of the synergistic effect between the Pd@Pt NPs and HRP in the presence of added H2O2. The differential pulse voltammetry signal is best acquired at a working potential of −250 mV (vs. Ag/AgCl) in the presence of H2O2. Under optimized conditions, the calibration range extends from 0.01 to 40 ng mL−1 of LMP-1, and the detection limit is 0.62 pg mL−1 (S/N = 3). Hence, this immunosensor provides a promising tool for an early diagnosis of nasopharyngeal carcinoma.