CTAB-Co-MOFs@AuPt NPs as signal probes for the electrochemical detection of carcinoembryonic antigen 15-3

Abstract

A sensitive electrochemical strategy for carcinoembryonic antigen 15-3 (CA15-3) detection is reported using CTAB-Co-MOFs@AuPt NPs as signal probes. The electrochemical strategy was designed as follows: First, the graphene aerogel@gold nanoparticles (GA@Au NPs) nanocomposites were employed to modify the sensing surface for promoting electron transfer rate and primary antibody (Ab₁) immobilization due to GA possesses a large specific surface area, eminent conductivity, and a 3D network structure. Cobalt metal-organic frameworks (CTAB-Co-MOFs) synthesized were then used as a carrier for AuPt NPs and secondary antibody (Ab₂) immobilization (notes: labelled-Ab₂). With sandwich immunoreaction, the labelled-Ab₂ was captured on the surface of the GA@Au NPs nanocomposites. Finally, differential pulse voltammetry (DPV) was employed to register the electrochemical signal of the immunosensor at the potential of - 0.85 V (vs SCE) in phosphate buffer saline (PBS) containing 2.5 mM H₂O₂. It was verified that the electrochemical reduction signal from Co³⁺ to Co²⁺ was recorded. The AuPt NPs could catalyze the reaction of H₂O₂ oxidizing Co²⁺ to Co³⁺, resulting in the amplification of the electrochemical signal. Under the selected conditions, the immunosensor can detect CA15-3 in the range 10 µU/mL to 250 U/mL with a low detection limit of 1.1 µU/mL. In the designed strategy, the CTAB-Co-MOFs were not only employed as carriers for AuPt NPs, but also acted as signal probes. The CTAB-Co-MOFs were investigated including SEM, TEM, XPS, and XRD. The application ability of the immunosensor was evaluated using serum sample, demonstrating the immunosensor can be applied to clinic serum analysis.

Keywords: Au Pt nanoparticles; Carcinoembryonic antigen 15–3; Differential pulse voltammetry; Electrochemical immunosensor; Metal–organic framework; Signal amplification.