Process engineering approach to large-volume methacrylate monolith synthesis for plasmid purification

The purification of plasmid DNA is hampered by the low performance of conventional chromatographic adsorbents which possess small particle pore diameters. Most of these adsorbents are tailored for the high adsorption capacity of proteins with size less < 10 nm. In columns packed with such adsorbents, large molecules such as pDNA with sizes > 100 nm adsorb predominantly at the particle outer surface, thus resulting in a low binding capacity. A monolith is a continuous phase consisting of a single piece of a highly porous organic or inorganic solid material. The most important feature of this material is that all the mobile phase is forced to flow through its large pores. As a consequence, mass transport is enhanced by convection; dramatically reducing the long diffusion time required by particle based chromatographic supports. Therefore, chromatographic separation process on monoliths is practically not diffusion-limited. The large pores of these monoliths allow penetration of large pDNA molecules to the internal surface area at high flow rate with low pressure drop. Different types of monolithic supports are currently available based on preparation and chemistry. These are silica-based, polyacrylamide-based and gel-based monolithic resins. Polymethacrylate monolithic support is an optimal adsorbent for pDNA separation. These adsorbents have large pore diameters and thus no significant hindrance to convective mass transport. They are resistant to pH, non-toxic, economically favorable to synthesize and can be easily modified by functionalizing with anion-exchange, hydrophobic interaction or affinity ligand. The flexibility and the ease to tailor their pore and surface characteristics to the target pDNA molecule through alteration in synthesis conditions make them more attractive.