Sedigheh Hashemnia

In this research, a new sensor based on aptamer and MIP for the detection of cardiac troponin I (cTnI)was investigated. The carboxylated ZnO/MWCNT nanocomposite was prepared and served as immobilization surface to bind amine-modified aptamers to the GCE surfaceFor MIP preparation, Tetrabromophenol blue dye (TBPB) was polymerized around the immobilized aptamer/cTnI complexes by electropolymerization. After removal of cTnI, the cavities were produced and converted into a new hybrid receptor (aptamer/MIP). Various techniques such as scanning electron microscope (SEM), X-ray energy diffraction spectroscopy (EDX), element mapping pattern (MAP), infrared spectroscopy (FT-IR), dynamic light scattering (DLS), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the different modification levels. The results show the electrocatalytic behavior of GCE modified with Poly-TBPB towards ascorbic acid (AC) oxidation, in 0.1 M phosphate buffer (pH 7.4). The experimental results confirmed that the Aptamer/MIP-modified GCE was a better probe for the detection of CTnI in the presence of AC, than in the absence of AC in the electrolyte solution. Therefore, a calibration curve was prepared based on the anodic peak of TBPB in the presence of AC, showing a linear response in the concentration range of 5-10000 pM. The selectivity of the prepared sensor towards cTnI protein was investigated in the presence of cardiac troponin T (cTnT), myoglobin (Myo), human serum albumin (HSA) and C-reactive protein (CRP), as interfering substances. The anodic DPV peak of the sensor, shows no significant change in the presence of interfering species. The fabricated sensor shows excellent analytical performance as the response to cTnI and exhibits ae detection limit of 0.13 pM, which is much lower than the clinical cut off level of 400 pg/mL (16pM).