Induction and analysis of aggregates in a liquid IgG1-antibody formulation

Both mechanical stress methods can provoke aggregate formation. The method of stirring induces particles in the range of 10-25 μm comparable to shaking stress. However, stirred samples show a much higher absorbance and reveal a second particle species in DLS analysis, suggesting that stirring stress induces a higher amount of smaller protein aggregates. Addition of polysorbate 80 protects the antibody against aggregation. Only in stirred samples a slight increase in sub-visible particles and turbidity was noted. However, a greater extent of aggregation products was detected by DLS as compared to surfactant-free formulations. Thus, polysorbate 80 appears to stabilise small aggregates and prevents further proceeding of the aggregation process. The induction of aggregates by stirring stress in Reacti VialsTM analysed by absorbance measurement seems to be a good combination for high-throughput formulation studies.