Reverse Micelle Extraction of Monoclonal Antibodies

Monoclonal antibodies (mAbs) are large proteins the body uses to fight many diseases and infections, and hence they are needed in larger and larger quantities. At the moment they are used in minute quantities for mainly diagnostic testing, and hence are very expensive. Most of this cost is due to their dilute nature in the biological fermentation they are produced in, and their separation on very expensive Protein A chromatographic columns which are very selective for the dilute amounts. This proposal wants to develop a very cheap method for purifying these mAbs using a solvent with very small aggregations of surfactants in it (Reverse Micelles-RM) which can selectively separate these mAbs from their original source. We want to study how fast this occurs, how we can use them to purify mAbs, and how we can stop them precipitating on the phase boundary between the two phases (fermentation broth and solvent).

The demand for mAbs in the world is rising rapidly due to its increasing use in therapeutic applications. Hence, there has to be a significant increase in the output required if these demands are to be met. While production can be scaled up, the costly process of downstream separation using Protein A chromatography columns has to be reduced in cost to make the antibody widely available. Reverse micelles are small (5-10 nm)surfactant aggregates in a solvent phase - when they are contacted with a broth they are capable of selectively separating proteins, and this has been demonstrated for large proteins (>100kDa) and mAbs, although recoveries are lower. The aim of this work is to look at the kinetics of extraction of large proteins and mAbs using a range of system parameters such as surfactant concentration and type to optimise its separation, and examine mAb structure in the RMs using CD/PCS/FTIR. Back kinetics into an aqueous phase will be looked at, especially if the mAb precipitates at the interface, and strategies will be developed to recover the mAb from the precipitate. Finally, a Graesser contactor will be used to contact the two phases, and mass transfer performance will be assessed in order to scale up the extraction.