Continuous Segmented-flow Polymerase Chain Reaction for High-throughput Miniaturized DNA Amplification

A continuous segmented-flow method for sequential DNA amplification is described in order to provide a basis for high-throughput genetic analysis. The approach allows an immediate distinction between amplified and nonamplified products. A mixture of sample and reagents are loaded in the form of small segments one after another in a 15-m-long narrow-bore Teflon tube, coiled such as to be repeatedly exposed to three different temperature zones. After having passed the heated zones, the samples are mixed with an intercalating dye by flow injection and sequentially detected on-line by laser-induced fluorescence. The aqueous samples travel as separate segments in a continuous flow of an immiscible, organic liquid. Perfluorodecalin was shown to be particularly suitable due to its hydrophobicity and inert properties. To reduce carryover between samples, an intermediate water plug between two consecutive samples was required. Selected regions from human genomic DNA were successfully amplified in 300-nL volumes after 30 passes through the heated zones. The total reaction time was approximately 45 min, and the detection interval between individual samples was 1 min. Automation and the possibility to further reduce sample volumes, as well as to employ many reaction columns simultaneously, should provide a platform for an extremely high throughput.