DNA based electrochemical biosensors

Nucleic acid recognition layers can be combined with electrodes to form new and important types of affinity biosensors as DNA based electrochemical biosensors. Genosensors or DNA hybridization biosensors are analytical devices for detection of specific DNA target sequences upon hybridization of the target with complementary probe immobilized on the solid substrate. Electrochemical DNA biosensors rely on the conversion of the DNA base pair recognition events into a useful electrical signal [1]. Recognition of electrochemical DNA hybridization is accomplished via two methods including direct and indirect. In direct DNA hybridization detection that carry out without any label, the signal induces owing to the inherent oxidation of adenine and guanine bases in DNA strands directly [2]. Whereas, in indirect method the oxidation or reduction signal of an electroactive indicator causes detection of hybridization event. Electrochemical indicators for detection of hybridization have usually small molecular weight and different affinities for ssDNA relative to dsDNA. In particular, DNA hybridization biosensors offer considerable promise for obtaining sequence-specific information in a simple, faster and cheaper manner, compared to traditional hybridization assays. Such new strategies hold enormous potential for clinical diagnosis of genetic of infectious diseases, for environmental monitoring or other investigations. The genetic disorders detection is obviously of importance for preventive health care. Numerous of these disorders are created by mutations happened in double stranded DNA (dsDNA) in our body cells, consists of the blueprint of our genetic makeup. The dsDNA is formed, when all the bases of which two complete complementary single strands DNA (ssDNA) bind to each other. If one mismatch happens in the base pairing process, single base-pair mismatch, single nucleotide polymorphism or SNP, is created which can lead to many disorders. In this works, I introduce some compound such as: brilliant cresyl blue, Indigo Carmine, ethyl green, ketamine and tyrosinase as new electroactive labels in electrochemical DNA oligonucleotide sensors based on various working electrodes [3-5], new PNA or DNA biosensor based on p53 tumor suppressor gene corresponding oligonucleo-tide [6] and proposed genosensor for recognition and determination of thalassemia gene [7], DNA damage detection [8], introduction of some drug as a G-Quadruplex-Binding Ligand [9] and electrochemical DNA-based biosensors for determination of some heavy metal ions [10].