Synthesis of polymeric particles of different shapes

Abstract

Biodegradable polymeric particles have been greatly researched on and used in a wide array of applications. These particles are of exceptional interest in drug delivery systems in a bid to move away from conventional methods of treatment. While particle size has been actively researched on for the past two decades, particle shape has only recently gained increasing attention. Initial studies have shown that shape may have a significant impact on carrier performance. However, the understanding the role of particle shape has been hindered by the lack of controlled fabrication techniques. In this study, solvent evaporation and film stretching method are investigated. PLGA is used for this study as it is one of the most successful polymers used in the production of particles for delivery. For solvent evaporation method, overhead stirrer stirring speed and polymer concentration is studied. It can be observed that sufficiently high stirring speed would result in a high mechanical force which distorts the polymeric particles. At low stirring speeds, the change in shape is due to the non uniform solvent evaporation rate within the emulsion droplet. In the film stretching method, effect of initial particle size, thickness of film, effect of different methods of liquefaction and effect of aspect ratio of stretching is investigated. Different stress applied to particles of different size and film of different thickness result in different resultant shapes with film stretching. Viscosity of particles and extent of stretching of particles also result in formation of different shapes. Scanning electron microscopy (SEM) is used to observe the different shape of the particles obtained. It is evident from the images that changing the parameters in each of the method investigated resulted in different shapes.