Microchip zone electrophoresis for high-throughput analysis of monoclonal antibody charge variants.

A high-throughput screening assay on a microfluidic chip was developed for the determination of charge variants of monocolonal antibodies (mAbs) in pI range of 7-10. This method utilizes microchip zone electrophoresis for rapid separation (<90 s) of mAb charge variants that are labeled fluorescently without altering the overall charge. The microfluidic assay achieves between 8- and 90-fold times faster separation time over conventional methods while maintaining comparable resolution and profiles of charge variant distributions. We further characterized the assay with respect to (i) the effect of pH on resolution, (ii) the effect of excipients and buffering agents, (iii) the performance of the assay compared to conventional methods, and (vi) the reproducibility of charge variant profiles. Finally, we explored the utility of the assay with four case studies: (i) monitoring C-terminal lysine modification of a mAb, (ii) quantifying the extent of deamidation of a mAb, (iii) providing charge variant information on which to base clone selection, and (iv) making process parameter-related decisions from a "design of experiment" (DoE) study. The results of these case studies demonstrate the applicability of the microfluidic assay for high-throughput monitoring of mAb quality in process development of biopharmaceuticals.