Label-Free Electrochemiluminescence Immunosensor for the Determination of Cardiac Troponin I Using a Cadmium Sulfide–Molybdenum (IV) Sulfide Nanocomposite Modified Glassy Carbon Electrode

A label free electrochemiluminescence (ECL) immunosensor for the determination of cardiac troponin I was developed using CdS-MoS2 composites as the electrochemiluminescence emitters. The CdS-MoS2 composites were synthesized by a hydrothermal method and used for the construction of the electrochemiluminescence biosensing platform. For the fabrication of the immunosensor, CdS-MoS2 composites, chitosan, cardiac troponin I antibodies, and bovine serum albumin were consecutively assembled on the glass carbon electrode. Under the optimum conditions, the label free electrochemiluminescence determination of cardiac troponin I was obtained. Due to the excellent electrochemiluminescence performance of CdS-MoS2 composites and high specificity of the immunoreactions, the sensor shows satisfactory selectivity and high sensitivity for cardiac troponin I determination. The detection limit was 1.0 pg mL−1 and the linear range was from 5.0 pg mL−1 to 100.0 ng mL−1. Moreover, the method was successfully used to determine cardiac troponin I in human serum samples with recoveries between 85.4 and 111.0%. This label-free immunosensor possesses many merits, including a simple sensing process, good electrochemiluminescence performance of the CdS-MoS2 composites, and high flexibility for extending the strategy for the determination of other biomarkers.