Development of electrochemical aptasensor for point of care detection of cardiac Troponin I biomarker

In recent years, myocardial infarction (MI) has posed a threat to human health, leading to higher rates of mortality and morbidity. According to the latest “world health organization” data, published in May 2014, heart disease deaths in Iran reached 29% of total deaths [1]. Among different biomarkers, cardiac Troponin I (cTnI) shows the highest specifity with the lowest amount in healthy people. Following myocardial damage Troponin complex is broken up, releasing into the blood stream. After 4-8 hours, cTnI increases from 0.1 ng/ml to a detectable range as high as 100 ng/ml and remains elevated for 4-10 days after the onset of MI. Therefore, the awareness of the concentration of this biomarker, considered as “gold standard”, gives the healthcare team to make vital decision in order to prescribe the right medicine in right time [2]. Meanwhile, a method capable of evaluation the amount of this biomarker with very fast response and acceptable analytical criteria plays a significant role. In this regards, electrochemical biosensors such as aptasensors are important in early diagnosis of MI where time-consuming and expensive laboratory tests are replaced with a range of point of care, low cost and friendly used devices [3]. Aptamers with the specific target binding are a powerful alternative for antibodies which have opened new horizons to achieve such desirable sensors [4]. The present study tries to introduce a label free single-step detection of cTnI in human blood serum. The thiolated aptamer has been immobilized on surface of screen printed gold electrode. The impedance spectroscopy and differential pulse voltammetry have been applied to monitor the attachment of cTnI with aptamer and record the analytical signal. The aptasensor works on signal-off mode which decreases the electrochemical signal of redox probe due to the capture of cTnI by an aptamer (Figure 1). The sensor shows the favorable correlation between the concentration of cTnI and analytical signal which has been led to the promising detection limit. It 317 is anticipated that the high selective aptasensor for cTnI and enormous potential of massproduction could be readily applicable for the accurate early diagnosis of MI.