(675e) Partitioning and Mass Transport for Continuous Two-Phase Extraction of Viral Vaccines

Biomanufacturing is trying to push past batch processing to continuous processes, an extremely beneficial technological leap that reduces costs, labor, and the footprint of the manufacturing plant. Aqueous two-phase extraction (ATPE) is a promising solution to enable this advance. The gentle environment afforded by ATPE is especially conducive to the purification of fragile whole-particle viral vaccines that are easily inactivated and too large to fit into the pores of conventional chromatography resins. Previously, we achieved over 80% recovery of two model viral products in the polymer phase of a PEG/citrate ATPE with high host cell protein and DNA removal in both batch and continuous modes. However, two major challenges to implementation exist: 1) optimization of efficient ATPEs for new viral vaccines is time and resource intensive, and 2) scale-up is hampered by a lack of understanding of the mass transport of viral particles in ATPE. To solve these problems, we designed two unique microfluidic channels. The first contains internal static mixer elements to increase interfacial area between the phases and hasten partitioning, allowing us to screen for optimum extraction conditions by changing the flow rates of our components. This greatly decreases development time and uses only microliters of solutions. A second microdevice allows direct observation of the transport of fluorescently tagged protein and virus particles across the interface of our ATPE. Using this device and a two-film transport model, we determined diffusion coefficients in each phase and the mass flux across the interface of porcine parvovirus. Combined, these tools represent a pathway to rapidly identify ATPEs for purification of new viral vaccine candidates and collect transport parameters required for scale up of continuous systems, all in a fraction of the time required for earlier manual optimizations. These findings will enable the design and scale-up of continuous downstream processes that provide the highest recovery possible using a small footprint and cost-effective equipment.