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Updated: Feb 9, 2026

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of GoldIII
Published on: August 31, 2018
Rotational Rheology of Bovine Serum Albumin Solutions: Confounding Effects of Impurities, Mechanistic Considerations
Jian Hua Gu1, Rulin Qian2, Robert Chou3
1Drug Product Technology, Amgen Inc., MS 8-1-C, One Amgen Center Drive, Thousand Oaks, CA, 91320, USA. Jiang@amgen.com.
Purpose:
To show and rationalize the confounding effects on the rotational/oscillatory rheology of surface active impurities in commercial protein formulations such as bovine serum albumin, BSA.
Methods:
Bulk and interfacial rotational/oscillatory rheology were used to study the viscosity, complex viscosity, storage/elastic modulus, G' and loss/viscous modulus, G", as a function of time of aqueous formulations of BSA and their purified components.
Results:
Viscosity/time profiles at steady shear for different commercial BSA products and lots showed viscosity increase, decrease and time-independent profiles at low shear rates. All lots showed shear thinning. BSA monomer and dimers/aggregates, in general, showed similar profiles. Addition of low levels of surfactant or high shear rates rendered all solutions to be Newtonian-like. Interfacial viscosity studies paralleled those on the rotational rheometer. G' > G" with viscosity increase and G' < G" with viscosity decrease over time.
Conclusions:
We provide a rational explanation for the time-dependent and source-dependent rheological behavior of aqueous formulations of commercially available BSA proteins based on the migration of protein and surface active impurities to the air/water interface within the rheometer plates leading to the formation and breakdown of protein networks. Highly purified proteins is warranted in rheological studies of protein drug product candidates.
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