Hybridization of DNA

Such layer structure does not allow ns to say a priori that hybridization of DNA will be possible, for it is protected by the octadecylamine layer. In order to control for this possibility, fluorescence measurements were performed. The first indication that hybridization was successful is that after the process, the sample surface became wettable, while before it and after cold hybridization it was not wettable at all. The results of the fluorescence measurements are summarized in Table 10. The results of the specific hybridization are three times more with respect to unspecific hybridization and one order of magnitude more with respect to cold hybridization. Thus, it appears that during a normal hybridization (100% homology) some structural changes and redistribution of the layer takes place. As a result, DNA becomes available for the specific reaction. Such a model also explains why the fluorescence level after unspecific hybridization (10% homology) is higher with respect to cold hybridization. Because the molecules have some mobility when the film is warmed, some DNA from the film could be hybridized on itself, while during cold hybridization this is impossible. 

The synthesis of conductive metallic nanowires that bridged two microelectrodes separated by a gap of 12-16 im was demonstrated by the growth of a silver nanowire on a DNA template that bridged the gap (Fig. 12.26).92 Short thiolated nucleic acids (12 bases long) were attached to the microelectrodes, and these acted as sticky ends for the hybridization of /.-DNA that bridged the gap. The association of Ag+ to the phosphate groups of the template, followed by their reduction with hydroquinone under basic conditions, resulted in the formation of Ag° nanoclusters on the DNA template. The subsequent enlargement of the Ag° seeds by the catalytic reduction of Ag+ by hydroquinone, under acidic conditions, yielded continuous Ag nanowires with a width of ca. lOOnm. The nanowires revealed nonlinear I—V... 

The hybridization of DNA strands from different sources forms the basis for a powerful set of techniques essential to the practice of modem molecular genetics. A specific DNA sequence or gene can be detected in the presence of many other sequences, if one already has an appropriate complementary DNA strand (usually labeled in some way) to hybridize with it (Chapter 9). The complementary DNA can be from a different species or from the same species, or it can be synthesized chemically in the laboratory using techniques described later... 

Other known oligonucleotide analogs include oligomers in which the heterocyclic bases have been modified [155] or replaced by other types of compound [156], Solid-phase syntheses of hybrids of DNA with peptides [157-163], with carbohydrates [164,165], and with PNA (peptide nucleic acids, see Section 16.4.1.2 [166-168]) have also been reported, and several strategies have been developed that enable the preparation of oligonucleotides with a modified 5 - or 3 -terminus [169-174] or of cyclic oligonucleotides [122,175], Various techniques for the parallel solid-phase synthesis of oligonucleotides have been developed for the preparation of compound libraries [176-181],... 

ELECTROCHEMICAL DETECTION OF THE HYBRIDIZATION OF DNA STRAND RELATED TO BRCA1 BREAST CANCER GENE USING A TWO STRANDS ASSAY FORMAT... 

For environmental applications, hybridization of DNA with other polymers is a recommendable approach for creating water-insoluble DNA ma-... 

Osmium tetroxide is an electroactive marker of the polynucleotide chain and is a good probe of the DNA structure since dsDNA is modified by osmium to a much lesser extent than single-stranded polynucleotides. The limit of detection of osmium-labelled DNA was below 5 ng cm-3 after 2 min accumulation time [66]. Adsorptive stripping linear sweep voltammetry of osmium tetroxide labelled DNA at a mercury electrode [66, 67] was shown to be a good sensor for hybridization of DNA. 

DNA chip technology is based on the hybridization of DNA probe sequences. For a proper hybridization, the probes have to be immobilized selectively on a modified 5 -end or 3 -cnd and in high yields. Since probes will be immobilized in large excess relative to the labeled targets, the kinetics of hy-... 

Zhang et al. reported a nanocomposite membrane of shuttle shaped ceria nanocrystals (Guo et al., 2008), SWNTs, and ILsl-butyl-3-methyli-midazolium hexafluorophosphate (BMIMPFg), which was incorporated on the glassy carbon electrode for electrochemical sensing of the immobilization and hybridization of DNA (Zhang et al., 2009). The electron transfer resistance (Pgt) of the electrode surface increased after the immobilization of probe ssDNA on the Ce02-SWNTs-BMIMPF6 membrane and rose further after the hybridization of the probe ssDNA with its complementary sequence. 

Hoogsteen The hydrogen bonds formed in the hybridization of DNA chains to form a... 

Kuhn H, Demidov W, Coull IM, Eiandaca MI, Gildea BD, Frank-Kamenetskii MD. Hybridization of DNA and PNA molecular beacons to single-stranded and double-stranded DNA targets. 42. J. Am. Chem. Soc. 2002 124 1097-1103. 

Fig. 23.9. Controlled deposition and hybridization of DNA on hydrophobic SU-8 surface patches (a—d) and defined displacement of DNA from such areas (e-f). (a) Schematic drawing of the individually labeled and cholesterol-modified DNA...

Electrochemical impedance measurements were also used to detect the hybridization of DNA on Si/Si02 chips and great emphasis has been put by Cloarec et al. [112] on the immobilization of single strands on the substrates in order to obtain reproducible sensors. The adsorption of dsDNA and nucleotides on a glassy carbon surface has also been evaluated by electrochemical impedance spectroscopy by Oliveira Brett et al. [113,114]. 

Beattie W G, Meng L, Turner S L, et al. (1995). Hybridization of DNA targets to glass-tethered oligonucleotide probes. Molecular Biotechnol. 4 213-225. 

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