Microchip for continuous DNA analysis based on gel electrophoresis coupled with co-injection of size markers and in-channel staining.

A continuous-flow microchip enabling high-accuracy DNA analysis was developed. Serial consecutive analysis for multiple amplified DNA samples was demonstrated. The sample segments were continuously introduced to the microchip from the PCR device which was interfaced to the microchip through capillary tubing. Electrokinetic co-injection of the DNA samples with size marker enabled reproducible and reliable injection of the DNAs into the gel-filled separation channel providing accurate size determination of the DNA samples. Cross-contamination between serially introduced DNA samples was minimized by plugging a washing solution segment following the previous sample segment between two sample plugs. Using this microchip, continuous separation of multiple samples was performed without any inconvenient and labor-intensive sample preparation steps such as sample mixing, staining, and gel loading which are necessary for conventional gel electrophoresis. It has taken about 4 min to separate single DNA sample and taken 37 min for three serially injected samples which implies that this microchip can be a platform device for fast as well as highly accurate DNA analysis.