This NSF award by the Chemical and Biological Separations program supports work by Professor Andrew L. Zydney in the Department of Chemical Engineering at The Pennsylvania State University to examine the use of membrane ultrafiltration for the large-scale purification of plasmid DNA. A number of clinical trials are currently underway on the use of plasmid DNA as a gene therapy agent or a DNA-based vaccine. However, one of the critical issues for the successful commercialization of this technology is the cost and challenge associated with the large-scale purification of plasmid DNA. Preliminary results obtained in our laboratory have demonstrated that plasmid transmission through ultrafiltration membranes is a strong function of the filtrate flux due to elongation of the plasmid within the flow field above the membrane. Our underlying hypothesis is that this flux dependence, and the associated differences in elongational flexibility of the different plasmid isoforms (linear, open-circular, and supercoiled), can be exploited to achieve high-resolution plasmid purification using membrane systems. Experimental studies will examine the behavior of different membranes, including both neutral and charged polymers, as well as the effects of solution environment and operating conditions on the ultrafiltration behavior of plasmid DNA. Data will be analyzed using appropriate models that account for the elongation of the plasmid due to flow. These results will provide fundamental insights and practical guidelines for the development of membrane systems for the removal of host cell proteins and the separation of different DNA isoforms. In addition, this research program will provide graduate and undergraduate students hands-on experience dealing with membrane processes for biomolecule purification, giving them an ideal background to pursue careers in the biotechnology and pharmaceutical industries.
