A simple electrochemical strategy for the detection of the cancer marker CA19-9 by signal amplification using copper organic framework nanocomposite

Abstract

In this work, label-free electrochemical immunosensing of the cancer biomarker carbohydrate antigen 19-9 (CA19-9) is reported using [Fe(CN)₆]^3−/4− as a signal probe and a copper organic framework (Cu-BTC) nanocomposite for the amplification of the signal. The immunosensor was fabricated by the following process. First, the Cu-BTC nanomaterial with a larger surface area and good biocompatibility was synthesized to improve the dispersion of gold nanoparticles (Au NPs). Then, nitrogen-doped graphene (N-GR) was combined with Cu-BTC to form the nanocomposite. The synthesized Cu-BTC@N-GR@AuNPs@CS nanocomposite was employed to modify the surface of the immunosensor to accelerate the electron transfer rate and improve the immobilization amount of CA19-9 antibodies (Ab). Various techniques, including TEM, SEM and XPS were used to characterize Cu-BTC and nanocomposites. Differential pulse voltammetry (DPV) was used to measure the electrochemical response of the immunosensor in [Fe(CN)₆]^3−/4−. The signal intensity of the immunosensor was linearly changed upon increasing the concentration of CA19-9 antigen from 10 μU mL⁻¹ to 100 U mL⁻¹, and a detection limit of 4.2 μU mL⁻¹ was achieved. Furthermore, the immunosensor showed good stability, reproducibility and specificity, indicating its potential application in clinical analysis.