Nanospheres for DNA separation chips

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We report here a technology to carry out separations of a wide range of DNA fragments with high speed and high resolution. The approach uses a nanoparticle medium, core-shell type nanospheres, in conjunction with a pressurization technique during microchip electrophoresis. DNA fragments up to 15 kilobase pairs (kbp) were successfully analyzed within 100 s without observing any saturation in migration rates. DNA fragments migrate in the medium while maintaining their characteristic molecular structure. To guarantee effective DNA loading and electrofocusing in the nanosphere solution, we developed a double pressurization technique. Optimal pressure conditions and concentrations of packed nanospheres are critical to achieve improved DNA separations.

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Figure 1: The new system using nanospheres and a double pressurization technique.
Figure 2: Effectiveness of DNA separations carried out using conventional polymers versus nanospheres with pressurization methods.
Figure 3: Visualization of single DNA molecules.


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This work was partially supported by a grant funding Core Research for Evolutionary Science and Technology from the Japan Science and Technology Agency, a grant from the New Energy and Industrial Technology Development Organization of the Ministry of Economy, Trade and Industry, Japan, a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Technology, Japan, and the 21st Century COE Program, Human Nutritional Science on Stress Control, Tokushima, Japan. We thank Chie Kuwahara, Ryosuka Kodaka and Fumiko Aboshi of the Tokyo University of Science and Eduardo Jule of the University of Tokyo for preparing the nanospheres. The authors would like to thank Tomoaki Hino, Ken Hirano, Fung Xu, Mohammad Jabasini, Hideya Nagata, Yasuko Tanaka and Emi Endo of the University of Tokushima for technical and secretarial assistance.

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Correspondence to Mari Tabuchi.

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Tabuchi, M., Ueda, M., Kaji, N. et al. Nanospheres for DNA separation chips. Nat Biotechnol 22, 337–340 (2004) doi:10.1038/nbt939

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