Electrochemistry of Nucleic Acids
The present boom in electrochemical studies of nucleic acids (NAs) is closely related to DNA sequencing techniques, which are indispensable in genomics. In the first half of the 1960s, it was believed that in difference to the RNA nucleotide sequencing,(1) sequencing of large genomic DNA would not be possible. Methods of DNA renaturation/hybridization were, however, available since 1960.(2, 3) The capacity of DNA to form molecular hybrids was used to test the genetic relatedness of some organisms, to study the specificity of hybridization of DNA with mRNA(2-4) and for other purposes.(5) The discovery of sequence-specific restriction endonucleases by the end of the 1960s(6) opened the door to specific cleavage and manipulation of DNA.(7) In about a decade, Maxam and Gilbert(8) and Sanger et al.(9) invented the technology underlying DNA sequencing based on gel electrophoresis, that is, an intrinsically slow method. Shortly afterward, solid-supported DNA hybridization using membrane blotting was applied for DNA analysis.(10) This technology has become popular among biochemists and molecular biologists(11) but with the arrival of genomic sequencing,(7) other techniques suitable for automated parallel DNA analysis have been developed. In the early 1990s, array technologies based on the immobilization of multiple specific DNA fragments or ODNs onto solid surfaces and the detection of DNA duplexes resulting from hybridization with complementary target DNA (tDNA) appeared as promising tools for DNA sequencing. Such detection required fluorescence or radioactive labeling of DNAs. These array technologies have greatly influenced genomics and proteomics and further development in this field still continues, seeking faster, more sensitive and specific and/or label-free methods based on various principles, including electrochemical (EC) ones. We believe that NA electrochemistry can still offer a number of interesting approaches, which can be particularly useful in decentralized DNA analysis.