Sandwich assay electrochemical aptasensors

Electrochemical methods of detection affinity interactions at the surfaces are rather effective due to their relative simplicity and low cost. Amperometric aptasensor based on sandwich assay was proposed by Ikebukuro et al. [42]. They used two aptamers selective to thrombin. 

Ikebukuro et al. [12] first reported an electrochemical aptasensor for the detection of thrombin based on a sandwich-based assay. Two different aptamers specific for thrombin were used the 29-mer thiolated aptamer and the 15-mer aptamer labeled with glucose dehydrogenase [GDH]. The thiolated aptamer was immobilized onto gold electrodes thrombin at different concentrations and then the enzyme-labeled aptamer was added to the aptamer-modified electrodes. The electric current generated by the addition of glucose was measured at 0.1 V vs. Ag/AgCl in a buffer containing... 

Another example of electrochemical aptasensor based on Au-NPs as labels for the detection of thrombin is reported by Zheng et al. [28]. The assay was based on a sandwich format, in which the aptamerl (15-mer DNA aptamer with an amino group at its 5 end) was immobilized onto carboxyl functionalized magnetic beads. Such aptamer-coated magnetic beads were used for capturing and separation. Thrombin and Au-NP-labeled aptamerll were then added to... 

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