Simultaneous electrochemical detection of multiple tumor markers using metal ions tagged immunocolloidal gold

• The multiple tumor biomarkers were sensitively detected.
• The signals of different metal ions were distinct without the signal amplification.
• Present method performed well on the detection of clinical serum specimens.

In this work, a sandwich-format electrochemical immunosensor has been fabricated in the aim of simultaneous detection of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) using metal ions tagged immunocolloidal gold nanocomposites as signal tags. The capture anti-CEA and anti-AFP were immobilized onto the chitosan–Au nanoparticles (CHIT–AuNPs) membrane modified glassy carbon electrode through glutaraldehyde (GA). The metal ion labels could be detected directly through differential pulse voltammetry (DPV) without metal pre-concentration, and the distinct voltammetric peaks had a close relationship with each sandwich-type immunoreaction. Under the optimized conditions, the multiplexed immunoassay exhibited good sensitivity and selectivity for the simultaneous determination of CEA and AFP with linear ranges of 0.01–50 ng mL−1. The detection limits for CEA and AFP are 4.6 pg mL−1 and 3.1 pg mL−1, respectively. The method was successfully applied for the determination of AFP and CEA levels in clinical serum samples, and the results were in good agreement with standard enzyme linked immunosorbent assay (ELISA). This approach gives a promising simple and sensitive immunoassay strategy for clinical applications.