(407f) Protein Stability At the Silicone Oil-Water Interface Using Single Molecule TIRF and Interfacial Tensiometry

Therapeutic protein solutions have become a popular strategy
in disease treatment.  However, protein aggregation is a significant problem
that must be understood and minimized in order to develop safer and more
effective treatments. Aggregation at the silicone oil-water interface is of
particular interest due to increased aggregation seen within prefilled glass
syringes coated with silicone oil. In this presentation, the authors
investigate the aggregation behavior of three model proteins (lysozyme, insulin,
and IgG) at the silicone oil-water interface. Single molecule total internal
reflection fluorescence microscopy (SMTIRFM) and interfacial tensiometry were
used to identify the aggregation mechanics of the three proteins on the
molecular level as well as demonstrate a connection between the microscopic
data and bulk solutions. SMTIRFM captures molecular interactions by directly
observing fluorescently-labeled proteins within a developing non-fluorescent protein
layer allowing the collection of molecular interfacial diffusion rates as well
as absolute adsorption kinetics. By directly capturing molecular interactions,
SMTIRFM delves into within the regime where interfacial tensiometry does not measure
any change in interfacial tension, known as the lag phase of protein adsorption.