Principal areas of research:
- Develop approaches to control nucleation and crystallisation of small molecule organic organic solids (polymorphism).
- Develop biocrystallisation as a downstream bioseparation for purification and isolation of biopharmaceuticals
- Study the role of surface properties in processability and manufacturability of powders, including the effect of processing on powder properties.
- Developing methods to experimentally measure powder surface energy heterogeneity and models to determine surface energy distributions.
Area 1: Approaches to Control Nucleation and Crystallisation of Small Molecules
My research group has demonstrated how the interface can be engineered to control crystallisation of polymorphs. The engineered surfaces we prepare have a combined feature of topography and surface chemistry. In this area of work, a polymorphic occurrence domain concept, TiPOD concept has been proposed to account for the influence of the interactions at the interface on the crystallisation of polymorphs.
Area 2: Biocrystallisation as a Downstream Separation Step
Progress has been made in the upstream production of biopharmaceuticals, though bottlenecks in downstream separations (DSB) of biopharmaceuticals still remains. Crystallisation of proteins, including biopharmaceuticals, has evolved to a stage where it is feasible to develop biocrystallisation as a downstream bioseparation for purification and isolation (increasing titer concentrations). Our work has demonstrated a “selective nucleation” concept, and coupled with flow crystallisation, can allow for the development of continuous biocrystallisation as an alternative to conventional DSB.
Area 3: Surface Properties in Processability and Manufacturability
A crystalline particle is typically assumed to be spherical and isotropic in surface properties. My work has demonstrated the highly facet specific properties of crystalline solids (anisotropic), evidenced experimentally for the first time for pharmaceutical solids. This area of work leads to an insight into the effect of processing (eg milling, crystallisation) on powder properties, the impact on processing (eg seeding, granulation, drying), and on the product performance (dissolution rate, fine particle fraction).
Area 4: Surface Energy Heterogeneity
My research here has developed approaches to determine powder surface energy heterogeneity and thermodynamics models to describe the surface energy site distribution. This gas chromatographic based technique is a more robust approach and provides a more complete description of the powder surface energy.