Electrochemical Detection of Cardiac Biomarker Troponin I at Gold Nanoparticle-Modified ITO Electrode by Using Open Circuit Potential

摘要

Gold nanoparticles (GNPs) have been electrodeposited on indium tin oxide (ITO) and applied to detectmolecular interaction between antigen and antibody by measuring open circuit potential (OCP). As acapture protein for immunoassay, specific monoclonal antibody against human cardiac troponin I(cTnI) was modified on the GNP coated ITO electrode surface by self-assembly and characterized byelectrochemical techniques. This is a simple, stable, and repeatable approach. The modified electrodecan be used to detect human cTnI. In this study, we adopted a new strategy to get an electrical signaldue to the enzyme-based immunecatalytic reaction by measuring the changes of OCP. This novelapproach can be applied to a simplified and miniaturized diagnostic system. A linear dependence ofOCP changes according to cTnI concentrations is observed in the range of concentration from 1 to 100ng/ml. Because the clinical borderline of cTnI between normal and patient is 0.5 to 2.0 ng/ml, ourresults indicate that the new approach using OCP changes has a great potential for clinical diagnosticapplication.