Electronic aptamer-based sensors

Willner, L, Zayats, M. (2007). Electronic aptamer-based sensors. Aw ew Chem Int Ed Engl 46(34), 6408-6418. 

Xiao, Y., Piorek, B. D., Plaxco, K. W., Heeger, A. J. (2005b). A reagentless signal-on architecture for electronic, aptamer-based sensors via target-induced strand displacement. J Am Chem Soc 127, 17990-17991. 

An electronic, aptamer-based small-molecule sensor for the rapid, label-free detection of cocaine in adulterated samples and biological fluids. J Am Chem Soc 128, 3138-3139. 

B. R. Baker, R. Y. Lai, M. S. Wood, E. H. Doctor, A. J. Heeger, and K. W. Plaxco, An electronic aptamer-based small-molecule sensor for the rapid label-free detection of cocaine in adulterated samples and biological fluids,/ Am. Chem. Soc., 128(10], 3138-3139 (2006]. 

Xiao, Y. Lubin, A. A. Heeger, A. J. Plaxco, K. W. Label-free electronic detection of thrombin in blood serum by using an aptamer-based sensor. Angew. Chem. Int. Ed. 2005, 44, 5456-5459. 

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. 

A very interesting biosensor was developed based on a similar principle for the detection of cancer cells [34]. The aptamer selected for acute leukaemia cells was fixed onto a gold electrode and electrochemical impedance spectroscopy (EIS) technique was used to characterize the surface with [Fe(CN)6] as a redox probe. Upon binding of the aptamer-modified electrode with leukaemia cells, the electron-transfer resistance of [Fe(CN)6] on the sensor surface increased substantially. A linear relationship was observed between the electron-transfer resistance and the concentration of the leukaemia cells in a range 1 x lO to 1 x 10 cells/mL with a detection limit of 6 x 10 cells/mL and high selectivity. 

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