Aptasensors changes

Figure 7.4 Label-free aptasensors based on CNT-FETs. (A) The aptamers are attached onto the sidewalls of a single-walled carbon nanotube which connects the source (S) and drain (D) electrodes. The binding of the target protein changes the electrical properties of the CNT-FETs significantly. (B) CNT-FET devices at high resolution. (See insert for color representation.)...

An electrochemical sensor with a nonlabeled redox probe shakes off probes labeled on the apatmers but still requires that the probes indicate changes on the sensing interface. One commonly nsed probe, methylene bine (MB), belongs to the phenothiazine family and is an aromatic cationic dye showing optically and electrochemically active properties (Tuite and Norden, 1994). Usually, MB can bind with dsDNA or tRNA via intercalation, electrostatic absorption, or G-base binding, which has been nsed widely in DNA sensors and recently, in aptasensors (Tuite and Norden, 1994 Bang et ah, 2005). 

Electrochemical Aptasensors Based on the Aptamer Conformational Changes... 

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. 

Electrochemical aptasensors based on target binding-induced aptamer conformational changes... 

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