Highly sensitive and direct detection of DNA fragments using a laser-induced capillary vibration effect

A pulsed laser-induced stationary wave capillary vibration detection method was applied to the sensitive detection of capillary gel electrophoresis, a nd the direct detection of non-labeled nucleic acids, such as DNA sequencin g 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 m atrixes to pulsed laser irradiation, a polyacrylamide without a cross-linke r (0%C) was found to have adequate endurance, and it exhibited no serious d amage during an analysis. A cytosine-terminated sequence reaction product w as detected with a sensitivity close to that of laser-induced fluorometry ( LIF) These results suggest the feasibility of the highly sensitive detectio n of ultramicro amounts of biological materials without a pre- or post-colu mn derivatization, which has usually been required in sensitive detection p rocedures, such as LIF. Furthermore, the feasibility of a novel DNA sequenc ing method is also suggested.