posted on 2024-03-06, 10:29authored byCéline van Haaren, Bernadette Byrne, Sergei G. Kazarian
Throughout bioprocessing, transportation, and storage,
therapeutic
monoclonal antibodies (mAbs) experience stress conditions that may
cause protein unfolding and/or chemical modifications. Such structural
changes may lead to the formation of aggregates, which reduce mAb
potency and may cause harmful immunogenic responses in patients. Therefore,
aggregates need to be detected and removed or ideally prevented from
forming. Air–liquid interfaces, which arise during various
stages of bioprocessing, are one of the stress factors causing mAb
aggregation. In this study, the behavior of an immunoglobulin G (IgG)
at the air–liquid interface was investigated under flow using
macro attenuated total reflection Fourier transform infrared (ATR-FTIR)
spectroscopic imaging. This chemically specific imaging technique
allows observation of adsorption of IgG to the air–liquid interface
and detection of associated secondary structural changes. Chemical
images revealed that IgG rapidly accumulated around an injected air
bubble under flow at 45 °C; however, no such increase was observed
at 25 °C. Analysis of the second derivative spectra of IgG at
the air–liquid interface revealed changes in the protein secondary
structure associated with increased intermolecular β-sheet content,
indicative of aggregated IgG. The addition of 0.01% w/v polysorbate
80 (PS80) reduced the amount of IgG at the air–liquid interface
in a static setup at 30 °C; however, this protective effect was
lost at 45 °C. These results suggest that the presence of air–liquid
interfaces under flow may be detrimental to mAb stability at elevated
temperatures and demonstrate the power of ATR-FTIR spectroscopic imaging
for studying the structural integrity of mAbs under bioprocessing
conditions.