Genosensors label-free detections

In literature two possibilities for the detection of a DNA hybridization event in the case of carbon SPE genosensor are reported to use electroactive indicators or to detect the guanine moiety signal per se (label-free). 

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. 

Label-free electrochemical hybridization genosensor for the detection of hepatitis B virus genotype on the development of lamivudine resistance. Anal Chem 77, 4908-4917. 

D. 0. Ariksoysal, H. Karadeniz, A. Erdem, A. Sengonul, A. A. Sayiner, and M. Ozsoz, Label-free electrochemical hybridization genosensor for the detection of hepatitis B virus genotype on the development of lamivudine resistance, Ana/y. Chem. 77(15), 4908-4917 (2005). 

The label-free DNA biosensor approach comprises the direct detection of changes of some electrical parameter from the hybridisation event. The first reported use of this kind of genosensor was by Wang et al In this work, the hybridisation event was detected by monitoring the decrease of the guanine peak of an immobilised DNA probe. 

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... 

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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