Electrochemiluminescence detection of cardiac troponin I based on Au–Ag alloy nanourchins

Abstract

In this work, an Au–Ag alloy nanourchin (Au–Ag alloy NU) based electrochemiluminescent (ECL) sensor for the measurement of cardiac troponin I (cTnI) was developed. The as-prepared Au–Ag alloy NUs exhibited higher specific surface area and better conductivity owing to their unique urchin-like morphology, which resulted in excellent electrocatalytic activity towards H₂O₂ in the luminol–H₂O₂ ECL system. We have found that the Au–Ag alloy NUs could enhance the ECL signal in the luminol–H₂O₂ solution. Based on these facts, a facile and label-free ECL immunosensor has been constructed for the analysis of cTnI, a cardiac biomarker, with a wide linear range of 3.5 pg mL⁻¹–350 μg mL⁻¹. This novel ECL immunosensor has good stability and reproducibility, showing potential application in clinical diagnostics. In addition, a non-enzymatic electrochemical sensor for H₂O₂ was also fabricated, with a wide linear detection range of 100 nM–200 μM, a low limit of detection of 45 nM and a fast response time (less than 2 s).