Electrochemical Aptasensors

Abstract

This review presents electrochemical aptasensors reported in the literature. Their development has been growing as evidenced by the increasing number of scientific publications on this subject since 2004. Aptasensors are presented according to their transduction mode, including the most described amperometric and impedimetric devices as well as FETs and the first very recently reported potentiometric aptasensor. Signal-on (positive readout signal) and less sensitive signal-off (negative readout signal) aptasensors are reviewed based on target binding-induced conformational change of aptamers or on target binding-induced strand displacement or even on both processes. Aptamerlabeled and aptamer label-free devices are presented separately.

Voltammetric aptasensors for protein disease biomarkers detection: A review

“…The bioreceptor will be responsible for the selectivity/specificity of the sensor response to a given target or group of targets of interest, thus minimizing the interference from other substances in complex mixtures (Viswanathan and Radecki, 2008). On the other hand, the transducer determines the sensitivity of the biosensor and is responsible for converting the biological signal into a measurable signal (Monošík et al, 2012;Sassolas et al, 2009). The selectivity and sensitivity of the bioreceptor and transducer make the biosensors an attractive analytical tool in several areas and applicable to a large variety of samples including body fluids, food, cell cultures and environmental samples Grieshaber et al, 2008;Sassolas et al, 2009).…”

“…Biosensors that use DNA or RNA aptamers as bioreceptors have been named "aptasensors" Hianik and Wang, 2009;Radi, 2011;Sassolas et al, 2009). The aptasensors emerged in the early 1990s with the discovery and introduction of aptamers as sensing probes (Ellington and Szostak, 1990;Tuerk andGold, 1990 cited in Cheng et al, 2009).…”

“…The large scale production of aptasensors is subject to some hurdles that must be overcome, such as the aptamer stability during immobilization and the signal detection in complex biological samples, mainly due to the interferences from other molecules that are also present in those samples (Hianik and Wang, 2009;Hianik et al, 2007). In biosensing applications, DNA aptamers are suitable for designing reusable aptasensors, whereas RNA aptamers allow single shot measurements since they are more susceptible to nucleases attack (Sassolas et al, 2009;Strehlitz et al, 2008). However, some chemical modifications can enhance nuclease resistance (i.e.…”

“…Therefore, the selected method should ensure that the binding affinity and selectivity of the aptamers in solution are kept in order to obtain the maximum activity whenever they are immobilized as the bioreceptor (Balamurugan et al, 2008;Velasco-Garcia and Missailidis, 2009). The immobilization methods usually applied are physisorption (physical adsorption), chemisorption (chemical adsorption), streptavidin/avidin/neutravidin-biotin interaction and covalent attachment via functional groups (Balamurugan et al, 2008;de-los-Santos-Álvarez et al, 2008;Sassolas et al, 2009;Zhou et al, 2011) (Fig. 3).…”

“…In the first method, no aptamer modification is required and the aptamer is immobilized on the electrode surface by means of electrostatic forces. This method is simple but, in general, it is not suitable for the development of reusable aptasensors due to the low stability resulting from the aptamers' desorption from the surface (Hianik and Wang, 2009;Paniel et al, 2013;Radi, 2011;Sassolas et al, 2009). In the other three methods, the aptamers are modified with a thiol group (-SH), a biotin protein and a chemical functional group (e.g.…”