Electrochemical/electrical detection/device

With the arrangement shown above, the reaction proceeds spontaneously, in which electrons move from left to right and X ions from right to left so that the electroneutrality is maintained. This type of reactions which take place in an electrochemical manner is called electrochemical reaction. A device like the one shown above, which permits a spontaneous electrochemical reaction to produce a detectable electric current, is termed a galvanic cell. As shown in the above figure, oxidation occurs in one half-cell and reduction occurs in the other half-cell. The electrode at which oxidation occurs is referred to as the anode, while the electrode at which reduction occurs is termed cathode. 

As mentioned before, several electrochemical biosensors based on direct DNA detection or catalyzed oxidation of DNA G residues require the combination of nanomaterials, DNA-recognition, and electrical detection protocols, allowing them to improve the sensitivity of the devices. Other promising technologies for the analysis of DNA through the use of labels, as described in the following section, have been obtained. 

In general, low level detection is masked by the noise level inherent in any measuring device. Electrochemical methods are susceptible to electrical interference from external sources, variations in reference electrode parameters resulting from aging or contamination, and interference from redox... 

Electrochemical devices have proven very useful for sequence-specific biosensing of DNA. Electrochemical detection of DNA hybridization usually involves monitoring a current response under controlled potential conditions. The hybridization event is commonly detected via the increased current signal of a redox indicator (that recognizes the DNA duplex) or from other hybridization-induced changes in electrochemical parameters (e.g., conductivity or capacitance). Modern electrical DNA hybridization biosensors and bioassays offer remarkable sensitivity, compatibility with modern microfabrication technologies, inherent miniaturization, low cost (disposability), minimal power requirements, and independence of sample turbidity or optical pathway. Such devices are thus extremely attractive for obtaining the sequence-specific information in a simpler, faster, and cheaper manner, compared to traditional hybridization assays. 

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