| Popis: |
Lipid particles have been widely utilized as drug delivery carriers as a result of their biocompatibility, bioavailibility and biodegradability. Lipid particulate drug carriers are often spherical, but more complex shapes have attracted more attention due to novel delivery benefits. Elongated particles are of increasing interest, for example, to improve deposition of active ingredients to the human lung. Manufacture of elongated particles normally involves shaping technologies such as microfluidic flows, film stretching processes, and particle-scale moulding or sculpting. Such methods can be expensive and be limited in scale. Here, we use two methods to produce elongated lipid particles with size scales able to improve the delivery efficiency from a flow. We study behaviour of the shapes in simple shear flow and compare with more common shapes. A hot emulsion method is used to crystallize a lipid emulsion, with careful choice of surfactant and co-surfactant to cause a unique dewetting phenomenon and generate elongated particles. The method can easily control the shape of the elongated particles, and allow tuning of shape, size and aspect ratio. Because of its simplicity, this method can be easily adapted to larger scales. The size and shape distribution of the particles are characterised and their behaviour in simple shear flow has been studied to understand their likely delivery traits. Building on the high-temperature process, a low-temperature emulsification method is also developed, allowing direct production of elongated particles via the same dewetting mechanism but without the need for extensive heating and cooling. The solvent emulsification method produces elongated particles similar to the hot emulsion process, but also produces novel shape gradient particles with oscillatory radial dimensions. The novel shape occurs due to instabilities during coupled evaporation and solidification and exhibits a more complex curvature than most elongated particles available. |
