Continuous precipitation of antibodies using oscillatory flow reactor: A proof of concept

Antibodies are among the most important drugs in the pharmaceutical industry. Their increasing demand has pressured the industry to increase upstream antibody titers, making downstream processing the new manufacturing bottleneck. Precipitation is an attractive alternative to current purification platforms by reducing costs, increasing yields and decreasing the scale-up process complexity. In the present work, continuous precipitation of antibodies using an oscillatory flow reactor (OFR) was explored. The combination of cross-linking (zinc chloride, ZnCl2) and volume exclusion (polyethylene glycol, PEG) agents was examined for precipitation of antibodies from an artificial IgG and FBS mixture, mimicking the supernatant of antibody-producing cells. The PEG/ZnCl2 ratio was first optimized in batch and further implemented in the OFR under continuous operation, where the influence of mixing intensity (frequency, amplitude and flow rate) was investigated. Continuous precipitation carried out in the OFR with 14% PEG6000 and 4 mM ZnCl2 enabled the recovery of over 99% of antibodies with 90% purity, demonstrating the implementation viability of this operation for the initial capture of antibodies. It must be also highlighted that precipitation did not affect the secondary structure of the antibody according to circular dichroism measurements.