Silk scaffolds achieved using pickering high internal phase emulsion templating and ionic liquids

We describe a convenient route to the preparation of silk scaffolds that does not require silk fiber dissolution and regeneration. We prepare the silk scaffolds via a single step pickering-high internal phase emulsion (HIPE) method. Additionally, we find that the use of biocompatible ionic liquids significantly improves the compressive properties of the HIPEs.

Silk powder: production, characterisation, and application

 For the first time, produced silk particles with unique properties in the range of 7 µm – 200 nm using milling process which opens up new opportunities for silk particle for diverse applications especially drug delivery and tissue scaffolds.

Programmed function of the tammar mammary gland; the role of milk proteins in gut development

 This thesis aimed to exploit the unique reproductive strategy of marsupials such as the tammar wallaby to prove that milk may regulate postnatal growth and development of organs such as the stomach.

Comparative analysis of caveolins in mouse and tammar wallaby: role in regulating mammary gland function.

Recent studies using the mouse showed an inverse correlation between the Caveolin 1 gene expression and lactation, and this was regulated by prolactin. However, current study using mammary explants from pregnant mice showed that while insulin (I), cortisol (F) and prolactin (P) resulted in maximum induction of the β-casein gene, FP and IFP resulted in the downregulation of Caveolin 1. Additionally, IF, FP and IFP resulted in the downregulation of Caveolin 2. Immunohistochemistry confirmed localisation of Caveolin 1 specific to myoepithelial cells and adipocytes. Comparative studies with the tammar wallaby showed Caveolin 1 and 2 had 70-80% homology with the mouse proteins. However, in contrast to the mouse, Caveolin 1 and 2 genes showed a significantly increased level of expression in the mammary gland during lactation. The regulation of tammar Caveolin 1 and 2 gene expression was examined in mammary explants from pregnant tammars, and no significant difference was observed either in the absence or in the presence of IFP.

Surface energy of silk fibroin and mechanical properties of silk cocoon composites

Silkworm cocoons are biological composite structures protecting the silkworms against environmental damage and physical attack by natural predators. In particular, some outdoor reared silk cocoons exhibit outstanding mechanical properties that are relevant to the higher level protection required to enhance the survival chance of silkworms while supporting their metabolic activity. The performance of composite materials strongly depends on the adhesion between the fiber reinforcement and matrix, with the surface properties of the fibers playing a key role in determining the level of adhesion achieved. For this reason it is important to study the surface properties of silk fibroin to further understand the composite properties of the cocoons. In this work, both the mechanical properties of the silk cocoons and silk fibroin were studied. The surface topography was examined using scanning probe microscopy (SPM), which revealed distinct longitudinal ridges and striations along the fiber axis of the four silk fiber types. The fibers were found to exhibit heterogeneity in surface energy as evidenced from inverse gas chromatography (IGC) measurements. The combination of excellent mechanical properties and the more energetically heterogeneous surface nature of the wild A. pernyi silk fibroin fibers correlates well with the excellent mechanical properties of the A. pernyi cocoons. This journal is

Effect of solvent on ionic liquid dissolved regenerated antheraea assamensis silk fibroin

We report on the dissolution of semi-domestic silk type Antheraea assamensis using ionic liquids. We investigated the impact of different coagulating solvents, including isopropanol and water on the structure and the morphology of the regenerated silk. We found that the water regenerated silk film showed a high β-sheet content and a native silk-like XRD pattern.

Relationship between processing, surface energy and bulk properties of ultrafine silk particles

Silk particles of different sizes and shapes were produced by milling and interactions with a series of polar and non-polar gaseous probes were investigated using an inverse gas chromatography technique. The surface energy of all silk materials is mostly determined by long range dispersive interactions such as van der Waals forces. The surface energy increases and surface energy heterogeneity widens after milling. All samples have amphoteric surfaces and the concentration of acidic groups increases after milling while the surfaces remain predominantly basic. We also examined powder compression and flow behaviours using a rheometer. Increase in surface energy, surface area, and static charges in sub-micron air jet milled particles contributed to their aggregation and therefore improved flowability. However they collapse under large pressures and form highly cohesive powder. Alkaline hydrolysis resulted in more crystalline fibres which on milling produced particles with higher density, lower surface energy and improved flowability. The compressibility, bulk density and cohesion of the powders depend on the surface energy as well as on particle size, surface area, aggregation state and the testing conditions, notably the consolidated and unconsolidated states. The study has helped in understanding how surface energy and flowability of particles can be changed via different fabrication approaches.