Label-free Electrochemical Immunosensor for Cardiac Troponin T Based on Exfoliated Graphite Nanoplatelets Decorated with Gold Nanoparticles

This paper describes the application of exfoliated graphite nanoplatelets (xGnP) decorated with gold nanoparticles (AuNP) for the development of a label-free electrochemical immunosensor for the determination of human cardiac troponin T (TnT), an important cardiac biomarker in the diagnosis of acute myocardial infarction (AMI). Heparin-stabilized AuNP (AuNP-Hep) were synthesized, characterized and supported on xGnP. The material obtained (AuNP-Hep-xGnP) was used as a platform to immobilize the anti-TnT by adsorption and this was then applied in the construction of an immunosensor. Under optimized conditions, using differential pulse voltammetry (DPV) and an incubation time of 20min, the proposed immunosensor showed linearity in the range of 0.050 to 0.35 ng mL(-1) TnT, with a calculated limit of detection of 0.016 ng mL(-1). The interday precision (n=7) showed a coefficient of variation of 6.5%. Some potential interferents commonly present in blood plasma samples were investigated and the degree of interference was found to be low (less than 10%), demonstrating adequate selectivity for analytical applications. The biosensor was successfully applied in the determination of TnT in fortified samples of human blood plasma.