Genosensors label-based detection

A novel label-free electrochemical genosensor for the detection of catechol-o-methyltransferase (COMT) Val 108/158Met polymorphism based on the guanine signal change by using a disposable CGE in connection with differential pulse voltammetry... 

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. 

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. 

Amperometric or voltammetric biosensors typically rely on an enzyme system that catalyt-ically converts electrochemically non-active analytes into products that can be oxidized or reduced at a working electrode. Although these devices are the most commonly reported class of biosensors, they tend to have a small dynamic range due to saturation kinetics of the enzyme, and a large overpotential is required for oxidation of the analyte this may lead to oxidation of interfering compounds as well (e.g., ascorbate in the detection of hydrogen peroxide). In addition to the use in enzyme-based biosensors, amperometric transducers have also been used to measure enzyme-labelled tracers for affinity-based biosensor (mainly immunosensors and genosensors). Enzymes which are commonly used for this purpose include horseradish peroxidase (HRP) [17] and alkaline phosphatase (AP) [18,19,21]. 

Li, C., Li, X., Liu, X. and Kraatz, H.-B. (2010) Exploiting the interaction of metal ions and peptide nucleic acids-DNA duplexes for the detection of a single nucleotide mismatch by electrochemical impedance spectroscopy. Anal. Chem., 82 (3), 1166-1169. Mohan, S., Nigam, P., Kundu, S. and Prakash, R. (2010) A label-free genosensor for BRCAl related sequence based on impedance spectroscopy. Analyst, 135 (11), 2887-2893. 

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