Droplet enhanced microfluidic-based DNA purification from bacterial lysates via phenol extraction

Microfluidic platforms have been developed to demonstrate DNA purification via liquid extraction techniques at the microscale using an aqueous phase containing either protein, DNA, or a complex cell lysate and an immiscible receiving organic (phenol) phase. Initially, a serpentine device was used to investigate protein partitioning between the aqueous and organic phase, and DNA purification when both protein and DNA were mixed in the aqueous phase and infused conjunctly with the phenol phase. This two-phase system was studied using both stratified and droplet-based flow conditions. The droplet-based flow resulted in a significant improvement of protein partitioning from the aqueous phase into the organic phase due to the convective flow recirculation inside each droplet improving material transport to the organic–aqueous interface. A second device was designed and fabricated to specifically extract plasmid DNA from bacterial lysates using only droplet-based flows. The plasmid recovery using the microdevice was high (>92%) and comparable to the recovery achieved using commercial DNA purification kits and standard macroscale phenol extraction. This study presents the initial steps toward the miniaturization of an efficient on-chip DNA sample preparation using phenol extraction which could be integrated with post-extraction DNA manipulations for integrated genomic analysis modules.