A highly sensitive label-free electrochemical immunosensor based on AuNPs-PtNPs-MOFs for nuclear matrix protein 22 analysis in urine sample

A reliable and non-invasive electrochemical immunosensor for nuclear matrix protein 22 (NMP22) was presented based on reduced graphene oxide-tetraethylenepentamine (rGO-TEPA) and gold nanoparticles‑platinum nanoparticles-metal organic frameworks (AuNPs-PtNPs-MOFs) nanomaterial . rGO-TEPA is a promising template to enhance the loading ability of electrode for its large specific surface area and abundance in amino groups. AuNPs-PtNPs-MOFs nanomaterial was synthesized by NaBH 4 reduction method and applied to immobilize biomolecules due to their good biocompatibility, well conductivity , and excellent H 2 O 2 electrocatalytic ability. The electrochemical response signal was primarily originated from the obstruction of immobilized NMP22 antigen towards electrocatalytic reduction of H 2 O 2 and the signal was recorded by differential pulse voltammetry . Under optimum conditions, the immunosensor showed a sensitive response towards NMP22 at a broad concentration range from 0.005   ng·mL −1 to 20   ng·mL −1 . Two strong linear ranges could be observed at 0.005   ng·mL −1 to 0.5   ng·mL −1 (R 2   =   0.9833), and 0.5   ng·mL −1 to 20   ng·mL −1 (R 2   =   0.9909), with a low LOD of 1.7   pg·mL −1 (S/N   =   3). Satisfactory reproducibility, stability and selectivity were obtained for NMP22 detection in real urine samples compared with standard ELISA assay, demonstrating the good analytical performance and potential non-invasive clinical application of this label-free electrochemical immunosensor.