Electrochemical genosensors

The application of genosensors in food industry could lead to immense improvements in various food industry processes. These devices can be used in the raw material selection. 

Edited by Alberto Escarpa, Marta Cristina Gonzalez and Miguel Angel L tez. 2015 John Wiley Sons, Ltd. Published 2015 by John Wiley Sons, Ltd. 

Genosensors enable one to improve the detection of food contaminants, reducing the health risks and medical costs associated with food-borne illness. Some of the contaminants that can be found in food are bacteria, virus, parasites, seafood toxins, mycotoxins, pesticides, toxic metals, veterinary drug residues, undesirable fermentation products, and so on [3]. 

As DNA is more thermostable than many proteins, analyses using nucleic acid are less liable to be disrupted by processing of foodstuffs. 

There are a variety of methods to detect the DNA content of food, which can be used to unequivocally identify the nature of the product [4]. Among the various systems for nucleic acid detection, electrochemical DNA analysis can involve direct detection based on a guanine signal (label-free) [5] or an electrocatalytic mechanism (label-based). Quantum dots (QDs) [6,7], metal nanoparticles (NPs) [8,9], enzymes [10,11], and metal complexes [12, 13] can be employed as labels. This chapter focuses on electrochemical biosensing systems based on DNA hybridization events, which offer novel routes for food safety and security applications. Particularly, it describes in detail different approaches reported in the latest years on the immobilization of oligonucleotides on electrochemical transducers for sensing of various compounds with interest in food industry. In addition, some interesting applications in other fields that can easily be extended to that of food are also included. 

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Physical or electrochemical adsorption uses non-covalent forces to affix the nucleic acid to the solid support and represents a relatively simple mechanism for attachment that is easy to automate. Adsorption was favoured and described in some chapters as suitable immobilization technique when multisite attachment of DNA is needed to exploit the intrinsic DNA oxidation signal in hybridization reactions. Dendrimers such as polyamidoamine with a high density of terminal amino groups have been reported to increase the surface coverage of physically adsorbed DNA to the surface. Furthermore, electrochemical adsorption is described as a useful immobihzation strategy for electrochemical genosensor fabrication. 

In aspect of chip-based technology, electrochemical genosensors based on different materials and transducers have been recently developed in response to clinical demand of giving promising results [18-25]. Different sensor technologies provide a unique platform in order to immobilize molecular receptors by adsorption, crosslinking or entrapment, complexation, covalent attachment, and other related methods on nanomaterials [5,7,26]. 

An overview on the genosensor technologies for detection of nucleic acids (NA) immobilized onto different transducers by adsorption, cross-linking, complexation and covalent attachment is briefly summarized in Table 19.1. The applications of electrochemical genosensor technology are discussed in the following section. 

In recent years, electrochemical genosensors developed on the principle of nanotechnology have become one of the most exciting forefront fields in analytical chemistry due to the recent advances in... 

M.I. Pividori, A. Merkoci and S. Alegret, Electrochemical genosensor design immobilisation of oligonucleotides onto transducer surfaces and detection methods, Biosens. Bioelectron., 15 (2000) 291-303. 

Data presented here demonstrate the potential applicability of SPCEs genosensors in the diagnosis of a human infectious pulmonary disease. These electrochemical genosensors are stable and sensitive devices for the detection of specific nucleic acid fragments. Moreover,... 

Although the spectrum of NPs for labelling applications is relatively broad, this chapter discusses only the application of gold NPs (AuNPs) in electrochemical genosensors and immunosensors and some of the trends in their use for environmental and biomedical diagnostics between other application fields. 

Electrochemical genosensors using AuNPs tags, with potential biomedical and environmental applications... 

Several protocols with potential biomedical and environmental application have been developed. Table 38.1 summarises information of some typical electrochemical genosensors based on DNA hybridisation detection using AuNPs tags. 

The development of electrochemical genosensors and immunosen-sors based on labelling with NPs has registered an important growth, principally for clinical and environmental applications. The electrochemical detection of NP labels in affinity biosensors using stripping methods allows the detailed study of DNA hybridisation as well as immunoreactions with interest in genosensor or immunosensor applications. 

Thus, this review will focus on an electrochemical genosensor developed using carbon screen-printed electrodes as the transducers the methods to immobilize DNA probes... 

Keywords Carbon screen printed electrodes Genosensors Electrochemical adsorption Hybridization event Electroactive indicators Indicator-free electrochemical genosensor... 

In the development of electrochemical genosensors, carbon screen-printed electrodes have been coupled with modern electro analytical techniques such as square wave voltammetry or chronopotentiometry at constant current, and... 

Typically, the basic steps in the design of an electrochemical genosensor are (a) immobilization of the DNA probe, (b) hybridization with the target... 

Hybridization Biosensing based on the Guanine Signal (Indicator-Free Electrochemical Genosensor)... 

In conclusion, we believe that procedures based on electrochemical genosensors will be more and more applied to other screening genotyping, and in clinical as well as environmental and food analysis. 

Ozkan D, Erdem A, Kara P, Kerman K, Meric B, Hassmann J, et a . Allele-specific genotype detection of factor V leiden mutation from polymerase chain reaction amphcons based on label-free electrochemical genosensor. Anal Chem 2002 74 5931-6. 

Kerman, K., Vestergaard, M., Nagatani, N., Takamura, Y. and Tamiya, E. (2006) Electrochemical genosensor based on peptide nucleic acid-mediated PCR and asymmetric PCR techniques Electrostatic interactions with a metal cation. Anal. Chem. 78, 2182-2189... 

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Ozsoz, M., Erdem, A., Kerman, K., Ozkan, D., Tugrul, B., and Topcuoglu, N. (2003) Electrochemical genosensor based on colloidal gold nanoparticles for the detection of factor V Leiden mutation using disposable pencil graphite electrodes. Anal. Chem., 75,2181-2187... 

Castaneda, M. T., Merkofi, A., Pumera, M., and Alegret, S., (2007) Electrochemical genosensors for biomedical applications based on gold nanoparticles. Biosens. Bio-electron., 22, 1961-1967... 

E. Williams, M. 1. Pividori, A. Merkofi, R. J. Forster, and S. Alegret, Rapid electrochemical genosensor assay using a streptavidin carbon-polymer biocomposite electrode. Biosens. Bioelectron., 19, 165-175 (2003). 

Table 4.3 summarizes data reported between 2007 and 2009 for electrochemical genosensors based on dsDNA-intercalated electrochemical labels. 

DNA immobilization step plays the most important role in determining the performance of an electrochemical genosensor (DNA-based biosensor) [15]. Control of the DNA binding surface in terms of surface orientation and coverage is essential for the sensitive monitoring of DNA-DNA and compound-DNA interactions by electrochemistry. 

The specific determination of interaction between DNA and related molecules is of impotance in the design of the electrochemical genosensors for application in diagnosis tests and in the design of new drugs, especially for chemotherapy. 

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