With a multitude of successful trials of gene therapies and DNA vaccines achieved, the next challenge is developing them into commercial products, requiring large quantities of purified plasmids.

The current favored method for purifying DNA plasmids is ion-exchange chromatography. Unfortunately, these membranes restrict the amount of plasmid binding due to small pore size and other various reasons. Limited binding of DNA plasmids on ion-exchange membranes has encouraged scientists to explore alternate methods to separate these negatively-charged molecules.

Scientists discovered that anion-exchange membranes possess larger pore sizes which can trap DNA plasmids more efficiently and allow for a greater volume of plasmids to be pumped through the membrane in a shorter time period. Unfortunately, these membranes bind DNA plasmids too strongly to allow for a reasonable recovery percentage for an industrial production process.

A novel anion-exchange membrane has been created that consists of a polypropylene membrane support covered in a hydrogel containing pores 1 log larger than the average ion-exchange membrane. The hydrogel coating ensures that the surface is hydrophilic allowing for an effective binding and release of the DNA plasmids. Typically this membrane is soaked in a liquid buffer for 30 minutes resulting in a 50-73% recovery of plasmids. Recovery can be improved dramatically to 76-89% by soaking the membrane in the liquid buffer for 16 hours. The extended soaking time creates larger, deeper, and more numerous pores in the membrane, trapping greater amounts of plasmid.

Alternate methods of DNA separation and purification have been developed using ion-exchange chromatography, anion-exchange membranes, and a patented AIRMIX(R) technology.