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Endotoxin inactivation via steam‐heat treatment in dilute simethicone emulsions used in biopharmaceutical processes
Author(s) -
Britt Keith A.,
Galvin Jeffrey,
Gammell Patrick,
NtiGyabaah Joseph,
Boras George,
Kolwyck David,
Ramirez José G.,
Presente Esther,
Naugle Gregory
Publication year - 2014
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1002/btpr.1903
Subject(s) - chemistry , biophysics , aqueous solution , gibbs free energy , chemical engineering , chromatography , thermodynamics , biology , organic chemistry , physics , engineering
Simethicone emulsion is used to regulate foaming in cell culture operations in biopharmaceutical processes. It is also a potential source of endotoxin contamination. The inactivation of endotoxins in dilute simethicone emulsions was assessed as a function of time at different steam temperatures using a Limulus amebocyte lysate kinetic chromogenic technique. Endotoxin inactivation from steam‐heat treatment was fit to a four‐parameter double exponential decay model, which indicated that endotoxin inactivation was biphasic, consisting of fast and slow regimes. In the fast regime, temperature‐related effects were dominant. Transitioning into the slow regime, the observed temperature dependence diminished, and concentration‐related effects became increasingly significant. The change in the Gibbs free energy moving through the transition state indicated that a large energy barrier must be overcome for endotoxin inactivation to occur. The corresponding Arrhenius pre‐exponential factor was >>10 12 s −1 suggesting that endotoxins in aqueous solution exist as aggregates. The disorder associated with the endotoxin inactivation reaction pathway was assessed via the change in entropy moving through the transition state. This quantity was positive indicating that endotoxin inactivation may result from hydrolysis of individual endotoxin molecules, which perturbs the conformation of endotoxin aggregates, thereby modulating the biological activity observed. Steam‐heat treatment decreased endotoxin levels by 1–2 logarithm (log) reduction (LRV), which may be practically relevant depending on incoming raw material endotoxin levels. Antifoam efficiency and cell culture performance were negligibly impacted following steam‐heat treatment. The results from this study show that steam‐heat treatment is a viable endotoxin control strategy that can be implemented to support large‐scale biopharmaceutical manufacturing. © 2014 American Institute of Chemical Engineers Biotechnol. Prog ., 30:1145–1160, 2014