Highly sensitive label-free electrochemiluminescence aptasensor for early detection of myoglobin, a biomarker for myocardial infarction

The authors describe an ultrasensitive electrochemiluminescence (ECL) based aptasensor for myoglobin, a biomarker for the early diagnosis of heart attack (myocardial infarction). A nanocomposite was prepared from reduced graphene oxide, ruthenium(II)-tris(2,2- bipyridyl), samarium oxide and chitosan and placed on the surface of a ccreen-printed carbon electrode (SPCE). The aptamer was immobilized via electrostatic interaction between the negatively charged aptamer and the positively charged nanocomposite which represents a remarkable immobilization platform. In the absence of myoglobin, the ECL signal of the ruthenium complex (generated at 1.2 V and peaking at 530 nm is weak. In the presence of myoglobin, a remarkable increase in ECL is observed due to the formation of the aptamer-myoglobin complex and the corresponding release of the labeled aptamercomplex from the surface. The response of the sensor is linear in the 0.05 to 25 nM myoglobin concentration range, with a 12 pM detection limit (at an S/N ratio of 3). The assay was successfully applied to the determination of myoglobin in spiked human serum and human urine samples where it gave recoveries that ranged from 96 to 105%, and from 95 to 103.7%, respectively. .