Molybdenum Disulfide Supported on Metal–Organic Frameworks as an Ultrasensitive Layer for the Electrochemical Detection of the Ovarian Cancer Biomarker CA125

Metal-organic frameworks (MOFs) are composed of metal ions/clusters and organic ligands, showing accessible functional sites, ultra-high porosity, and large specific surface area. Tricopper benzene-1,3,5-tricarboxylate (CuBTC), as a three-dimensional MOF architecture with an open and robust micro-/nanoconfiguration, possesses excellent catalytic performance and superior electric conductivity as compared to bulk MOF. In this study, CuBTC was used as a substrate on which molybdenum disulfide (MoS₂) was in situ constructed by a hydrothermal reaction to enhance the electron- and ion-transfer capability. Then, gold nanoparticles (AuNPs) were electroreduced on a CuBTC@MoS₂-modified electrode by linear sweep voltammetry for strengthening the connection between CA125 antibodies (CA125 Ab) and the substrate material. Due to the synergistic effect of CuBTC@MoS₂ and AuNPs, our biosensor showed excellent electrochemical performance. Subsequently, CuBTC@MoS₂-AuNPs/CA125 Ab-functionalized electrodes were used for the detection of the ovarian cancer biomarker CA125 from 0.5 mU/mL to 500 U/mL by differential pulse voltammetry. The results showed that the peak current decreased with the increase of concentration, and there was a logistic regression relationship between peak current variation and concentration. As interfering substances, carcinoembryonic antigen, human epididymis protein 4, and bovine serum albumin were applied for specific analysis. Our biosensor showed an obviously large response signal for CA125 detection than those observed for other interfering substances. Finally, serum samples collected from five patients were tested on our sensors with good consistency toward clinical standards, showing high practicability. This work demonstrated a tactic for simultaneously integrating the nanostructure, electroconductivity, and biocompatibility to construct advanced biosensors for cancer biomarkers.