BIOSENSORS 3 ELECTROCHEMICAL APTASENSORS

The potential use of aptamers as receptors in biosensors and bioassays has been extensively reviewed [1-7] and also several books have appeared in the last years [8,9]. In this chapter, the current status of research in electrochemical aptasensors is considered. Attention is focused on label-free and labeled aptasensors, and the anal3Aical capabilities of these devices are discussed. 

Hernandez EJ, Ozalp VC (2012) Graphene and other nanomaterial-based electrochemical aptasensors. Biosensors 2 1-14... 

In its simplest, QCM, format, protein-aptamer interactions were analyzed by Liss et al. (2002). They compared the interaction of IgE with DNA aptamer as well as with anti-IgE antibodies. Although the detection limit was similar in the two cases, the advantage of the aptasensor was its possibility of surface regeneration, which was impossible for an antigen-based biosensor. However, recently it has been shown that immobilization of anti-IgE on the dendrimer surface also allows us to regenerate an immunosensor (Svobodova et al., 2006). The QCM method was recently compared with the electrochemical biosensor assay of thrombin detection (Hianik et al., 2005, 2007). It has been shown that the sensitivity of thrombin detection was similar for the two methods. Mascini and co-workers showed that similar results in sensitivity and selectivity in the detection of Tat peptide with RNA aptamer can be obtained by the QCM and SPR methods (Tombelli et al., 2005b). 

Electrochemical biosensors based on DNA aptamers (aptasensors) are of growing interest due to their high sensitivity and selectivity. This is particularly due to unique properties of... 

Aptamer-based biosensors, also called aptasensor have gain a wide interest in the last years due to the advantages of aptamers compared to antibodies. Similar to antibodies, a variety of immobilization methods is available to bind aptamers to the sensor element. Aptasensors can be coupled to an electrochemical, optical or mass-sensitive transducer [13]. One of the successful examples for aptasensor was the detection of thrombin which was widely investigated [14]. Xiao et al. [15] have made an interesting development a redox compound (methylene blue) was inserted into the thrombin aptamer. When the target bound to the aptamer, the induced conformation change inhibited the electron transfer from the methylene blue to the electrode. This change could be detected amperometrically. 

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