DNA detection on a power-free microchip with laminar flow-assisted dendritic amplification.

In this paper, we describe DNA detection experiments using our two original technologies, power-free microchip and laminar flow-assisted dendritic amplification (LFDA), which were previously applied to immunoassays. A microchip was fabricated by combining a poly(dimethylsiloxane) (PDMS) part having microchannel patterns and a glass plate modified with probe DNA. We carried out two kinds of experiments: the detection of 21-base biotinylated target DNA and the detection of single-nucleotide polymorphism (SNP) in 56-base unlabeled target DNA by sandwich hybridization with biotinylated probe DNA. For both of the experiments, the necessary solutions were injected into microchannels not by an external power source, but by air dissolution into the PDMS part. After a hybridization reaction, the LFDA was started by injecting FITC-labeled streptavidin and biotinylated anti-streptavidin antibody onto the reaction site. With a detection time of 20 min, the limit of detection (LOD) for the biotinylated target was 2.2 pM, and the LOD for the SNP was 10-30 pM, depending on the SNP type.