Sensitive electrochemical thrombin aptasensor based on gold disk microelectrode arrays

The construction of a sensitive electrochemical aptamer sensor (aptasensor) for thrombin detection is described. Among the advantages of using microelectrode-based devices are the possibility to work with small sample volumes and enjoying faster mass transport rates and lower interfacial capacitance than at macroelectrodes. Therefore, gold disk microelectrode arrays are an attractive transducer option for aptasensors. The morphology of the gold disk microelectrode arrays was inspected by scanning electron microscope. The interaction between a thrombin aptamer and thrombin on gold disk microelectrode arrays was demonstrated by differential pulse voltammetry using methylene blue (MB) as an electrochemical indicator. MB adsorbed to aptamers via their guanine base. When thrombin was introduced, it displaced the MB adsorbed to the aptamers and bound to them. This resulted in a decrease of MB peak current which correlated to the concentration of thrombin over a dynamic range spanning from 10(-5) to 10(-12) M. This method was able to linearly and selectively detect thrombin with a detection limit of 0.143 pM. (C) 2012 Elsevier B.V. All rights reserved.