Purification and preconcentration of genomic DNA from whole cell lysates using photoactivated polycarbonate (PPC) microfluidic chips

We discuss the use of a photoactivated polycar- bonate (PPC) microfluidic chip for the solid-phase, reversible immobilization (SPRI) and purification of genomic DNA (gDNA) from whole cell lysates. The surface of polycarbonate was activated by UV radiation resulting in a photo-oxidation reaction, which produced a channel surface containing carboxylate groups. The gDNA was selectively captured on this photoactivated surface in an immo- bilization buffer, which consisted of 3% polyethylene glycol, 0.4 M NaCl and 70% ethanol. The methodology reported herein is similar to conventional SPRI in that surface-confined carboxylate groups are used for the selective immobilization of DNA; however, no magnetic beads or a magnetic field are required. As observed by UV spectroscopy, a load of 7.6 ± 1.6 mg/ml of gDNA was immobilized onto the PPC bed. The recovery of DNA following purification was estimated to be 85 ± 5%. The immobilization and purification assay using this PPC microchip could be performed within 25 min as follows: (i) DNA immobilization 6 min, (ii) chip washout with ethanol 10 min, and (iii) drying and gDNA desorption 6 min. The PPC microchip could also be used for subs- equent assays with no substantial loss in recovery, no observable carryover and no need for 'reactivation' of the PC surface with UV light.