WASEDA UNIVERSITY |
Application of Diamond for Biosensing
|
|||||||||
Semiconductor and Biotechnology The application of semiconductor technology for the bio technology is relatively new region of technology but the development of many techniques to detect the biomolecules has been demonstrated from a lot of research organizations. The fabrication of micro structure on many kinds of materials can be obtained by applying the semiconductor fabrication technique and the surface treatments such as plasma enhanced treatment confirm the change in the surface properties on materials. These techniques are supporting the IT society. In these days, many researcher are seeking the application of semiconductor technology to biotechnology. |
|||||||||
|
|||||||||
DNA sensor with diamond surface My research topic is the development of DNA sensor to detect the single-nucleotide-polymorphisms (SNPs). The DNA is fabricated by the sequence of four kinds of bases (A, T, G, C) and which codes the synthesis of protein. Generally, the two strands of complementary DNA makes the A-T or G-C pairs in these bases and form the double-helix structure (which is also called Watson-Click structure). The SNP is the site where the two bases in each DNA strands cannot fabricate the pair such as A and G or C and T etc. The existence of SNP is controlling the controlactability for such diseases and the affectability of some medicine. (See figure3. ) |
|||||||||
|
|||||||||
Figure5. Detection of DNA by the diamond electrolyte solution gate FET |
|||||||||
The detection of target DNA by the electrolyte solution gate FET is applied to detect the mismatched DNA. The hybridization efficiency of double strand DNA is degreased by the existence of mismatched site in target DNA which means the rate of immobilized double strand DNA is degreased when target DNA is mismatched. It indicates that the change in gate potential by the hybridization of mismatched DNA is smaller than that by the hybridization of complementary DNA and the mismatched DNA detection is determined by this difference of change in gate potential. Figure7. shows the result of mismatch detection on electrolyte solution gate FET. The difference of change in gate potential between complementary DNA and single-mismatched DNA is 3mV. [3] By advancement of this detection, the process of partially oxidation on gate surface is induced which cause the diamond surface more negative than the perfectly hydrogenated diamond surface. This negative charge originates the oxygen terminated surface can apply the repulsion force to DNA. The effect between the surface and DNA is degreased by this force and it makes the sensitivity of mismatched DNA increased. The difference of change in gate potential between complementary DNA and single mismatched DNA is increased to be 19mV by inducing this oxidation process. This difference is sufficiently large and it means the diamond electrolyte solution gate FET has sufficient sensitivity to discriminate mismatched DNA.[4] From now on, we investigate the interactions between diamond surface and DNA to develop the more sensitive detection method. And the interaction between RNA and binding protein will be inquired. References [1] G. J. Zhang, K. S. Song, Y. Nakamura, T. Ueno, T. Funatsu, I. Ohdomari, H.Kawarada,; Langmuir 2006, 22, 3728. |
|||||||||