Impedimetric detection development

An example of the selective detection of E. coli involved an impedimetric immunosensor developed using SAM-modified gold screen-printed electrodes (SPEs) [27]. In this... 

Although they have been successfully applied at the academic level, commercial devices are being developed [548,549]. Impedimetric immunosensors could potentially be used for qualitative purposes, such as, for example, in the detection of bacteria, pregnancy tests, allergy screening tests, etc [546]. 

Impedimetric biosensors represent a new and rapidly developing research area that permit the fast detection of biomaterials. Commercialization of such sensors is only beginning. More applications may be found in recent reviews [535, 543, 544, 546]. 

Another label-free impedimetric flow-injection immunosensor was developed for the direct detection of penicillin G [34]. Antipenicillin G was immobilized on a gold electrode modified with a SAM of thioctic acid. The real-time monitoring of impedance was carried out at the optimum frequency of 160 Hz. The detection limit of penicillin G in milk was reported to be 3.0 x 10 M. 

Figure 14.16 Scheme of the immunosensor reaction for the development of an impedimetric sensor for atrazine detection. An amount of the specific antibody is bounded on the coated antigen layer. The rest is evacuated of the IDyEs which is related to the atrazine concentration. Erom Ref [41 ] with permission from Elsevier... 

Figure 14.18 Nyquist plot of the impedance spectrum corresponding to the development of an impedimetric immunosensor for atrazine detection (a) Step I antigen immobilization and (b) Step II incubation step. The impedance spectra include three regions (i) diffusion control, (ii) first semicircle, and (Hi) second semicircle. From Ref [41] with permission from Elsevier...

Mantzila, A.G., Maipa, V., and Prodromidis, M.I. (2008) Development of a faradic impedimetric immunosensor for the detection of salmonella typhimurium in milk. Anal Chem., 80, 1169-1175. 

On the other hand, Ocafia et al. (2012) reported a simple, label-free impedimetric aptasensor for the detection of THR in PBS buffer solutions. In the design of the aptasensor, a graphite epoxy composite was used and the aptamers were immobilized onto the electrode surface by physical adsorption. A detection limit of 4.5 pM was achieved using EIS in the presence of the [Fe(CN) ] " redox probe. The aptasensor was regenerated for several cycles. Recently, Liu et al. (2015) developed an impedimetric aptasensor, using AuNPs for signal amplification and the redox probe [Fe(CN) ] , for detection and quantification of MUCl in PBS buffer solutions. 

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