A plastic microchip for nucleic acid purification

Abstract

A microchip for purifying nucleic acids from bacterial pathogens was designed and fabricated in plastic. The fabricated plastic microchips were tested for their ability to purify nucleic acids from the bacteria Listeria monocytogenes (L. monocytogenes), Escherichia coli (E. coli), and Salmonella typhimurium (S. typhimurium). These chips were constructed using rapid and low-cost plastic fabrication techniques including hot embossing and plastic casting. Silicon molds fabricated by photolithography and dry etching were used for chip prototyping. Zeonor plastic (poly (cycloolefin) resin) and epoxy microchips were fabricated using hot embossing and plastic casting, respectively. A low temperature sputtering technique was used to coat a layer of silicon dioxide onto the channel region for nucleic acid binding in chaotropic salt solutions. The purification channels contain an array of features to increase the surface area for DNA binding and purification. DNA was quantified with PicoGreen fluorescent dye and the quality of the material as a substrate for polymerase chain reaction (PCR) was tested using target specific primers. DNA could be recovered from the microchip and detected using PCR from a minimum of 10⁶ of L. monocytogenes, E. coli, and S. typhimurium cells, respectively. With the simplicity of the plastic chip’s fabrication and DNA purification, our microchip makes it ideal for a miniaturized DNA testing system.