A Sensitive Electrochemiluminescent Biosensor For Label-free Immunoassay Of C-peptide Based On AuNPs Functionalized ITO

The C-peptide is a co-product of pancreatic ?-cell during the secretion of insulin,its content in body-fluid closely relates to the condition of diabetes.This paper will report an immune-sensing strategy for simple and effective assay of C-peptide based on the label-free electrochemiluminescent(ECL)signaling,with high sensitivity,specificity,reproducibility and stability.An indium tin oxide(ITO)glass is employed as the conductive substrate,and the Au nanoparticles(Au NPs)was immobilized on it with(3-aminopropyl)trimethoxysilane as the linker,to construct the basal electrode.The character of fabricated electrode was investigated by electron microscope,cyclic voltammetry and electrochemical impedance spectroscopy.After immobilizing the C-peptide antibody which takes great advantage of Au NPs’ binding capacity,this immunosensor can quantify C-peptide using luminol as ECL probe.On account of the quenched ECL output in different degrees,the calibration can be established to report the C-peptide concentration within a wide linear range as four orders of magnitude from 0.05 ng m L-1 to 100 ng m L-1 and a detection limit of 0.0142 ng m L-1.As a proof of concept,the proposed strategy provided a promising and versatile platform for the clinical diagnosis,classification and research of diabetes.