Use of advanced analytical tool to predict protein solution properties

Antibody therapeutics, which comprise the largest share of the market in biologics, are often required as highly concentrated liquid formulations. In many cases, at such high protein concentrations, the solutions phase separate or display poor rheological properties, which limits their manufacturability. As such, approaches are needed for predicting the concentrated solution behaviour from models based on measurements made on dilute protein solutions, which is essential for early-stage drug development when not much protein material is available. In this studentship we mainly tackle the problem of predicting the concentrated solution viscosity, which remains an unresolved problem. The problem is solved using using a combination of experimental and computational tools derived from biophysics and soft matter physics.
The main goal of the studentship is to determine the relationship between a dilute solution viscosity parameter called the Huggin's coefficient and the concentrated solution viscosity, which is motivated by our preliminary study indicating there exists a strong correlation between these properties. Most approaches for correlating high concentration viscosity measurements with dilute solution properties rely on thermodynamic measurements of protein-protein interactions. Our main premise is that dilute solution measurements of protein-protein interactions (PPIs) are not sensitive to hydrodynamic properties of the protein solutions, which are a key factor in determining the viscosity. We expect combining PPI measurements with values of the Huggin's coefficient, which is much more sensitive to hydrodynamic interactions, will lead to improved predictors of high concentration viscosity. The project is broken up into three workpackages. In the first workpackage (WP1), we will build up an experimental dataset of Huggin's coefficient values and concentrated solution viscosity measurements, complemented with dilute solution PPI measurements to establish correlations between the dilute and concentrated solution parameters. This workpackage will also include analytical ultracentrifugation (AUC) in sedimentation velocity (SV) mode to obtain directly the hydrodynamic contribution to protein-protein interactions in dilute protein solutions. With these measurements complete, in the second workpackage (WP2) we will develop models for predicting the Huggin's coefficient from other dilute solution properties to elucidate the role of hydrodynamic interactions in controlling viscosity at low protein concentrations. Once we understand the relationship between hydrodynamic interactions and dilute solution viscosity, in the third workpackage (WP3) we will focus on developing models for predicting the concentrated solution viscosity and to establish the molecular basis for the correlations with dilute solution parameters such as k_H.
We expect the main deliverables will be
- A correlation relating k_H to concentrated solution viscosity along with an understanding of its limitations in terms of PPI measurements.
- Predictive models for calculating concentrated solution viscosity from measurements of k_H and other dilute measurements of PPIs.
- An improved molecular understanding for the causes of high concentration viscosity and the mechanisms of viscosity-reducing excipients to guide rationale design of formulations