Sensitive and antifouling impedimetric aptasensor for the determination of thrombin in undiluted serum sample

A highly sensitive and attractive antifouling impedimetric aptasensor for the determination of thrombin in undiluted serum sample was developed. The aptasensor was fabricated by co-assembling thiol-modified anti-thrombin binding aptamer, dithiothreitol and mercaptohexanol on the surface of gold electrode. The performance of aptasensor was characterized by atomic force microscopy, contact angle and electrochemical impedance spectroscopy. In the measurement of thrombin, the change in interfacial electron transfer resistance of aptasensor was monitored using a redox couple of Fe(CN)(6)(3-/4-). The increase in the electron transfer resistance was linearly proportional to the concentration of thrombin in the range from 1.0 to 20 ng/mL and a detection limit of 0.3 ng/mL thrombin was achieved. The fabricated aptasensor displayed attractive antifouling properties and allowed direct quantification of extrinsic thrombin down to 0.08 ng/mL in undiluted serum sample. This work provides a promising strategy for clinical application with impressive sensitivity and antifouling characteristics. (C) 2012 Elsevier B.V. All rights reserved.