A label-free immunosensor for the detection of nuclear matrix protein-22 based on a chrysanthemum-like Co-MOFs/CuAu NWs nanocomposite

Abstract

In this study, a new, simple, and label-free electrochemical immunosensor was presented for the detection of nuclear matrix protein-22 (NMP-22). In order to accurately monitor very small amounts of NMP-22, it was advantageous to use highly efficient nanomaterials as signals. For this reason, we synthesized a chrysanthemum-like nanocomposite (Co-MOFs/CuAu NWs), using Co-based metal–organic frameworks (Co-MOFs) as carriers and copper gold nanowires (CuAu NWs) wrapped around their surface, which was applied for modifying a glassy carbon electrode (GCE). The Co-MOFs/CuAu NWs possessed outstanding catalytic capabilities, which served as signal materials and simultaneously carried the anti-NMP-22 antibody (Ab). When different concentrations of the NMP-22 antigen (Ag) were specifically attached to the immunosensor, the current responses decreased by varying degrees. The designed biosensor used the principle to establish a linear regression equation and achieve an accurate quantification of NMP-22. After optimization, the NMP-22 sensor exhibited a good linear response over a concentration range from 0.1 pg mL⁻¹ to 1 ng mL⁻¹, with a lower detection limit of 33 fg mL⁻¹ (based on S/N = 3). The proposed biosensor demonstrated the advantages of ultra-sensitivity, high specificity and acceptable reproducibility, suggesting that the proposed strategy has the potential for the quantification of NMP-22 in human urine samples. Moreover, the novel nanocomposite Co-MOFs/CuAu NWs are promising materials for electrochemical sensors to detect other biomolecules.