Real-time imaging of monoclonal antibody film reconstitution after mechanical stress at the air-liquid interface by Brewster angle microscopy.

Monoclonal antibodies (mAbs) represent an important part of biological pharmaceutics. A serious challenge in their development is the formation of protein particles, which are often formed through protein aggregation at the air-liquid interface and then introduced into solution by interfacial stresses. In this paper, protein films formed at the air-liquid interface by two mAbs were disrupted by puncturing them with a microscopic needle, and the subsequent reconstitution of the film was observed in real-time by Brewster angle microscopy. Our results indicate that film reconstitution pace depends on mAb bulk concentration. Numerical modeling gives a quantitative prediction of the surface reconstitution. By extrapolating the model to concentrations typical for pharmaceutical formulations (>30 mg/mL) reconstitution timescales of the protein films can be estimated to be shorter than 0.01 s. Moreover, the effect of polysorbate 80 addition on protein film was studied. Film reconstitution measurements revealed that polysorbate 80 inhibits the film reconstitution process and breaks up the previously formed film.