Rapid analysis of nucleic acids from biological samples has been advanced by the development of microfluidic technologies capable of extracting nucleic acids from cell lysates and other sources. Rapid extraction methodologies can be combined with amplification techniques such as polymerase chain reaction (PCR) to provide useful quantities of nucleic acids from minute samples of blood, tissue, cultured cells, or other biological materials. These microfluidic technologies have been widely adopted in biomedical research laboratories, permitting, for example, high-throughput screening of cloned DNA “libraries” from cultured bacteria or other host cells.
The need for devices, systems, and methods for extracting nucleic acids from biological samples is well-recognized, and particular devices and methods are known in the art. Commonly used methods for extracting DNA on such a small scale exploit the tendency for DNA to bind to materials such as silica gel, silica membranes, porous glass, or diatomaceous earth. One such system provides a microcentrifuge tube containing the DNA binding media (known as a “spin column”). The sample is loaded into the tube and spun in a centrifuge, whereby the DNA is captured and the liquid phase containing contaminants passes through to the bottom of the tube. Such a procedure is disclosed in, for example, U.S. Pat. No. 6,821,757, to Sauer et al. Although spin column technology has been widely adopted by the research community, the resulting DNA is often of low quality for use in downstream applications such as PCR, and the need to pipette multiple samples into open tubes results in a significant risk of sample contamination. Moreover, such methods are time-consuming when performed manually and very expensive to automate.
One or more of the present inventors have disclosed particular methods and systems for extracting nucleic acids in U.S. Pat. No. 8,163,535, to Reed et al., which is hereby incorporated by reference in its entirety; and in U.S. patent application Ser. No. 12/948,566, to Reed et al., published as US 2011/0203688 A1 on Aug. 25, 2011, which is also hereby incorporated by reference in its entirety. These methods and systems employ a smooth glass surface for capturing nucleic acids and provide certain advantages over spin columns, including simplified work flow and resistance to contamination.
The successful use of rapid DNA extraction techniques in research has led to an interest in developing devices and processes through which this technology can be used in medical applications such as point-of-care diagnosis or testing of blood components. Recent progress toward more simple and compact devices has been reviewed by Malic et al., Recent Patents on Engineering 1:71-88, 2007. Despite these recent advances, there remains a need in the art for devices and processes by which high-quality DNA and RNA can be rapidly and economically extracted from samples containing nucleic acids.