Published online 6 June 2006
Methods Online |
Purification and preconcentration of genomic DNA from whole cell lysates using photoactivated polycarbonate (PPC) microfluidic chips
gorzata A. Witek1,21 Center for Biomodular Multi-Scale Systems, Louisiana State University Baton Rouge, LA 70803, USA 2 Department of Chemistry, Louisiana State University 232 Choppin Hall, Baton Rouge, LA 70803, USA
*To whom correspondence should be addressed. Tel: 1 225 578 1527; Fax: 1 225 578 3458; Email: chsope{at}lsu.edu
Received August 1, 2005. Revised September 7, 2005. Accepted March 16, 2006.
We discuss the use of a photoactivated polycarbonate (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 immobilization 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 µg/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 subsequent assays with no substantial loss in recovery, no observable carryover and no need for ‘reactivation’ of the PC surface with UV light.