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

In recent years, myocardial infarction (MI) has posed a threat to human health, leading to higherrates 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]. Amongdifferent biomarkers, cardiac Troponin I (cTnI) shows the highest specifity with the lowestamount 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 detectablerange 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 thehealthcare 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 responseand acceptable analytical criteria plays a significant role. In this regards, electrochemicalbiosensors such as aptasensors are important in early diagnosis of MI where time-consuming andexpensive laboratory tests are replaced with a range of point of care, low cost and friendly useddevices [3]. Aptamers with the specific target binding are a powerful alternative for antibodieswhich 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 bloodserum. 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 theattachment of cTnI with aptamer and record the analytical signal. The aptasensor works onsignal-off mode which decreases the electrochemical signal of redox probe due to the capture ofcTnI by an aptamer (Figure 1). The sensor shows the favorable correlation between theconcentration of cTnI and analytical signal which has been led to the promising detection limit. It is anticipated that the high selective aptasensor for cTnI and enormous potential of massproductioncould be readily applicable for the accurate early diagnosis of MI.

Keywords:

Myocardial infarction , Cardiac troponin I , Label-free detection , Signal-off mode , Aptasensor