Water Proton NMR: A Tool for Protein Aggregation Characterization

Formulation stability is a critical attribute of any protein-based biopharmaceutical drug due to a protein's inherent tendency to aggregate. Advanced analytical techniques currently used for characterization of protein aggregates are prone to a number of limitations and usually require additional manipulations with the sample, such as dilution, separation, labeling, and use of special cuvettes. In the present work, we compared conventional techniques for the analysis of protein aggregates with a novel approach that employs the water proton transverse relaxation rate R₂(¹H₂O). We explored differences in the sensitivity of conventional techniques, size-exclusion chromatography (SEC), microflow imaging (MFI), and dynamic light scattering (DLS), and water NMR (wNMR) toward the presence of monoclonal antibody aggregates generated by different stresses. We demonstrate that wNMR outperformed SEC, DLS, and MFI in that it was most consistently sensitive to increases in both soluble and insoluble aggregates, including subvisible particles. The simplicity of wNMR, its sensitivity, and possibility of noninvasive measurements are unique advantages that would permit its application for more efficient and higher throughput optimization of protein formulations.