Competitive bulk and surface hybridization. In presence of dsDNA in solution, competitive bulk hybridization occurs. Solutions with wild type and mutated DNA lead to competitive surface hybridization.
DNA microarrays (“chips”) are devices for the parallel analysis of nucleic acids (NA) mixtures allowing the identification of the different sequences present in the sample. A DNA chip comprises of an array of microscopic “spots” each carrying numerous single-stranded (ss) oligonucleotides of known sequence known as probes. The array is placed in contact with a mixture of labeled NA known as targets. Each target preferentially hybridizes, forms a double helix, with the complementary probe. The composition of the mixture is deduced form the label intensity of the different spots. To appreciate the necessity for DNA chips recall that the human genome comprises of approximately 30,000 genes. The challenge is to simultaneously monitor their levels of expression in different cells and under different conditions as well as to study the role of million or so of single nucleotide polymorphisms. Massively parallel method of analysis is necessary in order to meet these objectives. During the ten years since the invention was announced the production of DNA chips became an industry and their use in biomedical research is now routine. On the other hand, this technology confronts two major problems: (i) The results obtained using DNA chips of different origins exhibit significant disagreements. (ii) The results are obtained in arbitrary units and do not allow to specify the concentration of the targets in the solution. These difficulties are partially due to incomplete understanding of the hybridization behavior at the surface. Thus, our researchs, in collaboration with E. B. Zhulina, aims to formulate a detailed theory of the thermodynamics and kinetics of hybridization in DNA chips having in mind quantitative analysis of experimental results.
Maj : 13/10/2011 (307)