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

Abstract

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 20 min, 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.

Nanomaterials‐based Electrochemical Sensing of Cardiac Biomarkers for Acute Myocardial Infarction: Recent Progress

“…It is one of the most sensitive analytical methods used to detect trace analytes [23]. These characteristics lead to the development of electrochemical biosensors for different cardiac biomarkers such as myoglobin [10], troponin I [15], troponin T [2], thrombin [24], Creatine kinase-MB [25], etc.…”

“…There are different types of metal nanocatalysts with attractive electrocatalytic capacity suitable for the construction of cardiac biomarkers sensors. Metal nanoparticles are very important in the fabrication of electrochemical biosensors due to their higher surface area, high biomolecules adsorption capacity, excellent conductivity, biocompatibility, and good catalytic properties [2]. For example, gold nanoparticles (AuNPs) have become an ideal catalyst for biosensors because of their good electronic conductivity, easy preparation, and large surface area with a good biocompatibility suitable for biomolecules such as RNA, DNA, proteins, etc.…”

“…TnI and TnT are absent in the blood of healthy people because they are released into the bloodstream due to death of the myocardial cells and this makes them important biomarkers for AMI diagnosis [6]. The cTnT is one of the well-known cardiac protein markers and is released rapidly of the contractile apparatus in cardiac muscle within 2-4 h after AMI symptoms appearance and can be kept elevated for up to 14 days, thus it is regarded as a specific and sensitive biomarker for myocardial injury diagnosis [2,48]. On the other hand, the cTnI is considered as gold standard for the diagnosis of AMI not only because it is absent in skeletal muscles, but also its concentration in the bloodstream increases and remains elevated for 8 to 10 days, providing longer window of detection for myocardial infarction [4][5].…”

“…Acute myocardial infarction (AMI) or heart attack is the heart condition caused by the abrupt stop of blood circulation from the heart [1]. It is one of the world's leading causes of morbidity and death [2]. Thus, the development of the early and accurate diagnosis methods for AMI are needed to facilitate immediate treatment of patient and reduce possible risks [3].…”

“…These biomarkers are released into the bloodstream and the detection of their small changes in the blood can help to rapidly and correctly diagnose the corresponding disease [4,5]. Currently, the important cardiac biomarkers for the diagnosis of AMI are cardiac troponin I (cTnI) and T (cTnT), myoglobin (Mb), creatine kinase-MB (CK-MB), thrombin, and heart fatty acid binding protein (H-FABP) [2][3]8].…”