Abstract: A spiral-channel flow-through PCR microchip reactor with 35 cycles, which reduced the dispersion and flow resistance of reaction solution, has been developed. A PCR amplification of a 6 012 bp-base pair fragment from λ-DNA was successfully performed on the chip in₂6 min, which is much faster than the reaction time(3 h) with conventional PCR. By transporting the solutions through the capillary instead of PTFE tubing, the dead volume of the sequential injection(SI) system was reduced from 14 to 0.30 μL. The SI system is capable of automatic manipulation of microliter samples in the PCR system, including continuous PCR amplification, autosampling and microchannel washing. Seven samples could be continuously amplified in 1 h and no cross-contamination between samples in serial treatments was observed. The standard deviations of the amplified fragment sizes and peaks area analyzed by a microfluidic chip-based capillary electrophoresis system, for replicates number 7, were 0.4% and 6.7%, respectively.

Key words: PCR amplification, Sequential injection, PCR microchip, Long fragment gene