Evaluation of silica resins for direct and efficient extraction of DNA from complex biological matrices in a miniaturized format

For DNA purification to be functionally integrated into the microchip for h igh-throughput DNA analysis, a miniaturized purification process must be de veloped that can be easily adapted to the microchip format. In this study, we evaluate the effectiveness of a variety of silica resins for miniaturize d DNA purification and gauge the potential usefulness for on-chip solid-pha se extraction. A micro-solid-phase extraction (mu SPE) device containing on ly nanograms of silica resin is shown to be effective for the adsorption an d desorption of DNA in the program-nanogram mass range. Fluorescence spectr oscopy as well as capillary electrophoresis with laser-induced fluorescence detection is employed for the analysis of DNA recovered from solid-phase r esins, while the polymerase chain reaction (PCR) is used to evaluate the am plifiable nature of the eluted DNA. We demonstrate that DNA can be directly recovered from white blood cells with an efficiency of roughly 70%, while greater than 80% of the protein is removed with a 500-nl bed volume mu SPE process that takes less than 10 min. With a capacity in the range of 10-30 ng/mg of silica resin, we show that the DNA extracted from white blood cell s, cultured cancer cells, and even whole blood on the low microliter scale is suitable for direct PCR amplification. The miniaturized format as well a s rapid time frame for DNA extraction is compatible with the fast electroph oresis on microfabricated chips. (C) 2000 Academic Press.