Analytical Sciences

Highly Sensitive and Direct Detection of DNA Fragments Using a Laser-Induced Capillary Vibration Effect

Tamao ODAKE,*  Kin-ichi TSUNODA,* Takehiko KITAMORI,**^,*** and Tsuguo SAWADA**

*Department of Chemistry, Gunma University, Kiryu 376-8515, Japan
**Department of Applied Chemistry, School of Engineering, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-8656, Japan
***Integrated Chemistry Project, Kanagawa Academy of Science and Technology, Sakado, Takatsu, Kawasaki 213-0012, Japan

A pulsed laser-induced stationary wave capillary vibration detection method was applied to the sensitive detection of capillary gel electrophoresis, and the direct detection of non-labeled nucleic acids, such as DNA sequencing products, was demonstrated. An excimer laser operating at 248 nm was used as a CVL excitation source, and polynucleotides were sensitively detected without derivatization. From an investigation on the endurance of several matrixes to pulsed laser irradiation, a polyacrylamide without a cross-linker (0%C) was found to have adequate endurance, and it exhibited no serious damage during an analysis. A cytosine-terminated sequence reaction product was detected with a sensitivity close to that of laser-induced fluorometry (LIF). These results suggest the feasibility of the highly sensitive detection of ultramicro amounts of biological materials without a pre- or post-column derivatization, which has usually been required in sensitive detection procedures, such as LIF. Furthermore, the feasibility of a novel DNA sequencing method is also suggested.

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