Quantitative and qualitative analyses of DNA fragments based on electrical charge detection on a portable electrophoresis device

A concept regarding DNA fragments electrophoretic analyses by directly detecting electrical charges is proposed. The arrival time and voltage of charged DNA fragments with different charge-to-mass ratio could be detected using the custom-made micro electronic circuits. These time and voltage information imply the size and intensity information acquired from the conventional slab gel image by fluorescent labeling. A prototype of the portable electrophoresis device consists of a flow channel with the dimension of 35 mm (length) /spl times/ 0.5 mm (width) /spl times/ 0.2 mm (depth) on an acrylic substrate, and the detection circuit with amplification gain of 10,000 and analogous filter bandwidth between 0.1 Hz and 10 Hz has been developed. A simple experiment was carried out to demonstrate the feasibility of proposed idea. The volume of 2/spl mu/l of the DNA ladder (1 Kb Plus DNA ladder, Invitrogen, U.S.A.) with the diluted concentration of 0.1/spl mu/g//spl mu/l was loaded into the reservoir when applying the electrical field of 12.5 V/cm to both end of the flow channel, which was only filled with TBE solution. The preliminary results showed that the developed electrophoresis device can pick up the electrical signals of un-separated DNA fragments with total mass of 0.2 /spl mu/g , and the magnitude is 0.6 V . Micro flow channels fabricated by an excimer-laser machine and low-noise amplifier with high gain, e.g. 100,000 are being processed. Moreover, HEC (hydroxyethylcellulose) solution will be utilized as the media in the micro channels for DNA fragments separation.