Electrochemical Aptasensors Based on a Competitive Assay

In literature no many examples of electrochemical enz5mie-labeled aptasensors based on a competitive assay are present. The advantages of a competitive format (direct and indirect) are mainly related to the fact that only one aptamer is required (considering that two or more aptamers are not selected for many target anal ftes) and the time necessary for the assay is faster. 

A disposable electrochemical competitive assay for detection of IgE was proposed by Papamichael et al. [16]. In this work the IgE antigen was immobilized on the surface of screen-printed electrodes, then a competition step between IgE bound to the electrode surface and IgE in solution for the biotinylated aptamer was left to occur. At this point the streptavidin-alkaline phosphatase conjugate 

Centi et al [18] described various approaches for the development of electrochemical aptasensors for the detection of thrombin using magnetic beads as solid support and carbon 

Very high specificity toward neomycin B was observed with respect to other very similar antibiotics. Application of the method to the analysis of real samples was also demonstrated by testing neomycin spiked whole milk with a recovery of 102% and 109%, respectively, for two different neomycin concentrations. 

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