DNA electrochemistry

The electrochemical behaviour of DNA and adsorption at different types of electrodes has been investigated for a number of years [23-25], first using a dropping mercury electrode and more recently solid electrodes. 

Electrochemical oxidation of natural and synthetic nucleic acids at carbon electrodes pyrolytic graphite [34], paraffin-wax-impregnated spectroscopic graphite [35] and glassy carbon [36, 37] has been studied. It was shown that at pH 4.5 the electrochemical activity of nucleic acids is conditioned by the presence of purine residues in polynucleotide chains. 

Moreover, natural nucleic acids give rise to two well-separated oxidation peaks in differential pulse voltammograms, which can be used to probe individual adenine-thymine (AT) and guanine-cytosine (GC) pairs in double helical DNA during its conformational changes [38]. Differences in signals obtained at carbon electrodes were observed according to whether, or not, the DNA was denatured [39]. 

A very different detection approach was used [40] based on the electro-catalytic oxidation of sugars and amines at a copper electrode surface. The ssDNA and dsDNA were detected in the picomolar concentration range. The electrochemical signal due to dsDNA was higher than due to ssDNA owing to the larger number of easily accessible sugars on the outer perimeter of dsDNA double helix compared to those on a ssDNA of the same size, in contrast to most electrochemical studies based on the electroactivity of the bases. 

However, flow injection direct amperometric detection at carbon paste electrodes [42] was used for measurements of nucleic acids down to the 0.5 ng level without time-consuming derivatization or hydrolysis steps. 

---

Different strategies of electrochemical sensing have been used for DNA electrochemical detection (1) direct DNA electrochemistry, (2) indirect DNA electrochemistry, (3) DNA-specific redox indicator detection, (4) DNA-mediated charge transport, and (5) nanoparticle-based electrochemistry amplification. 

Girousi, S. and Stanic, Z. (2011) The last decade of carbon paste electrodes in DNA electrochemistry. Curr. Anal. Chem., 7, 80-100. 

Acetonitrile and hydrogen cyanide are hy-products that may he recovered for sale. Acetonitrile (CH3CN) is a high polarity aprotic solvent used in DNA synthesizers, high performance liquid chromatography (HPLC), and electrochemistry. It is an important solvent for extracting butadiene from C4 streams. Table 8-1 shows the specifications of acrylonitrile, HCN, and acetonitrile. ... 

Electrogenerated chemiluminescence (ECL) has proved to be useful for analytical applications including organic analysis, ECL-based immunosensors, DNA probe assays, and enzymatic biosensors. In the last few years, the electrochemistry and ECL of compound semiconductor nanocrystallites have attracted much attention due to their potential applications in analytical chemistry (ECL sensors). 

A series of ferrocenylmethyl nucleobases has been synthesized and the interactions with DNA in aqueous solution have been studied by electrochemistry (109,110). The neutral (rf— C5H5)Fe(r/5 — CgH4CH2-) derivatives were prepared by alkylation of the corresponding base with (rf — Cr>H5)Fe(rf— C5H4CH2N(CH3)J (110). For thymine and cyto-... 

To solve and at the same time to deeply understand the quite complicated and multidisciplinary task of lield-effect-based DNA biosensors, many disciplines and research fields, scientists from bio- and electrochemistry, biophysics, device engineering, and analytics should work hand in hand. 

Y.D. Jin, Y. Shao, and S.J. Dong, Direct electrochemistry and surface plasmon resonance characterization of alternate layer-by-layer self-assembled DNA-myoglobin thin films on chemically modified gold surfaces. Langmuir 19, 4771—4777 (2003). 

S.M. Chen and S.V. Chen, The bioelectrocatalytic properties of cytochrome c by direct electrochemistry on DNA film modified electrode. Electrochim. Acta 48, 513-529 (2003). 

Directional walk of atoms 42 DNA 341 Dominant pole 265 Eddy-current damper 248 Elasticity theory 365—376 Electrochemical tip etching 282—285 Electrochemistry 323... 

The observation of currents attributable to the faradaic electrochemistry of nucleic acids was pioneered by Palecek and coworkers who studied DNA adsorbed on mercury or carbon electrodes [13]. The signals detected by Palecek were attributable to oxidation of the purines, which produced signals indicative of irreversible processes involving adsorbed bases. These reactions were used as a basis for electrochemical analysis of DNA. Kuhr and coworkers later showed that similar strategies could be developed for analysis of nucleic acids via oxidation of sugars at copper electrodes [14-16]. 

Consequently, the electrochemistry of the Fc marker can be observed, allowing for highly sensitive detection of complementary DNA (cDNA). The presence of single-nucleotide mismatch in the duplex causes, presumably, a blockage of the -conduction pathway through the base stack at the position of the base-pair... 

Like the currently popular area, called nanoscience , the field of supramolecular chemistry has rather hazy boundaries. Indeed, both areas now share much common ground in terms of the types of systems that are considered. From the beginning, electrochemistry, which provides a powerful complement to spectroscopic techniques, has played an important role in characterizing such systems and this very useful book goes considerably beyond the volume on this same topic by Kaifer and Gomez-Kaifer that was published about 10 years ago. Some of the classic supramolecular chemistry topics such as rotaxanes, catenanes, host-guest interactions, dendrimers, and self-assembled monolayers remain, but now with important extensions into the realms of fullerenes, carbon nanotubes, and biomolecules, like DNA. 

E. Palecek and F. Jelen, Electrochemistry of nucleic acids and development of DNA sensors, Crit. Rev. Anal. Chem., 32(3) (2002) 261-270. 

---