Droplet-based Extraction of Hepatitis B Virus DNA in a Capillary

A novel capillary droplet-based DNA-extraction method was developed, using the principle of water-in-oil droplet formation in a highly hydrophobic polytetrafluoroethylene capillary. By sequentially introducing droplets containing a sample or reagents, all the steps related to Hepatitis B virus DNA extraction from blood, including sample injection, DNA binding, magnetic bead rinsing, and DNA elution were continuously implemented in the capillary. Experimental results showed that Proteinase K lysis and elevated elution temperature facilitated higher extraction efficiency. Under optimized conditions, an extraction was completed within 25 min with microliter level consumption of the sample or reagent. The droplet-based method achieved an extraction efficiency of about 60%, which was comparable to that of conventional methods, with the relative standard deviation of extraction efficiency for the droplet-based method being relatively higher. In summary, the herein-developed droplet-based DNA-extraction method is simple, fast, and economic, thus having the potential to be integrated into a micro-total analysis system for nucleic acids.