A molecularly imprinted electrochemical sensor with tunable electrosynthesized Cu-MOFs modification for ultrasensitive detection of human IgG

Human IgG is one of the most important immunoglobulins in the human body. The present study described the fabrication of four kinds of layer-by-layer structures of copper metal-organic frameworks (Cu-MOFs) on the working electrode by electrodeposition, which were then applied as an electrochemical sensor for the sensitive determination of IgG in serum. First, MOFs synthesized using different deposition potentials are expected to have varied morphology and properties. Herein, four copper MOFs (Cu-MOFs) were electrosynthesized by a simple and direct reduction approach. The as-synthesized Cu-MOFs exhibit varied morphology and electrocatalytic behavior. Then, IgG was employed as a template in the electropolymerization of pyrrole-imprinted films on the surface of glassy carbon electrodes. Finally, the template protein was removed to form a molecularly imprinted film with the capability to qualitatively and quantitatively signaling of IgG. Under optimized conditions, the sensor for IgG exhibits a wide detection range of 0.01–10 ng mL⁻¹ with a limit of detection (LOD) of 3 pg mL⁻¹ (S/N = 3). Besides, other parameters including the selectivity, reproducibility (RSD 3.6%), and recovery rate (95.2–102.0%) are all satisfactory. The practicability of the sensor was verified by detecting IgG in human serum samples, which indicated that the sensor was suitable for potential clinical applications.