Polymeric particle formation through electrospraying at low atmospheric pressure

Abstract

Electrospraying is a simple and versatile technique capable of producing polymeric particles. However, most investigations carried out thus far have been performed at ambient atmospheric pressure without studying the influences of pressure on the formation of polymeric particles. Here, we report our investigation on the effects of varying the pressure and the solution concentration on the microstructures of electrosprayed polymeric particles. Pressures are varied from ambient atmospheric pressure to 380 mmHg below ambient pressure, and solution concentrations are varied over a range of 3-7 w/v %. By varying these parameters, we manipulated the rate of solvent evaporation and the solidification of the electrosprayed particles. The results show that changes to the pressure had significant effects on the microstructure and morphology of poly(epsilon-caprolactone) (PCL) particles. The average particle size became larger as the chamber pressure decreased. At a solution concentration of 5 w/v % and a pressure 150 mmHg below ambient pressure, uniform and spherical PCL particles were generated. Electrospun fibers were formed when a solution concentration of 7 w/v % was used. The developed technique can be applied to prepare polymeric drug delivery carriers though a low-pressure-assisted spray-drying method, and is particularly suitable for fabricating delivery microspheres encapsulated with temperature-sensitive drugs and biomolecules.

Electrospraying, a Reproducible Method for Production of Polymeric Microspheres for Biomedical Applications

“…The spherical morphology was obtained only for high polymer concentrations (9 and 10 %w/v), while flattened morphology and coalescence between particles was observed for decreased polymer concentrations (5 and 7.5 %w/v) ( Figure 2). These results are in accordance with previous studies, where polymer concentration was often shown to be the most critical parameter in the morphology of electrosprayed particles [33]. …”

“…Chloroform has a much lower boiling point of 61.2 °C, explaining the textured surface that was observed. Such texture was also seen in an even more pronounced way when electrospraying PCL with dichloromethane [33], which boils at 40 °C, corroborating this theory. In the case of in vivo implantation, it is noted that the topographical complexity of a biomaterial is preferred for cell attachment since it generates an increased number of anchoring sites for cells [38].…”

“…Initially, the electrospraying parameters chosen in this work were based on previous studies on optimization of electrosprayed particles [15,[26][27][28][29][30]33,36,37]. Temperature and relative humidity ranged from 22 to 24 °C, and 44 to 49% respectively.…”

“…PCL is highly permeable to small drug molecules and degrades through its ester linkages. As compared to PLGA-based polymers, it also presents the advantage of a lesser acidic environment being generated during degradation [31], however, only very few studies have investigated the production of electrosprayed PCL particles [33][34][35]. As aforementioned, the type of polymer will give different characteristics of electrosprayed particles and due to the complexity and inter-dependence of variables involved in the process, PLGA production parameters might not be translatable to PCL.…”

Preparation of High-Payload, Prolonged-Release Biodegradable Poly(lactic-<i>co</i>-glycolic acid)-Based Tacrolimus Microspheres Using the Single-Jet Electrospray Method

“…Our results were consistent with previous findings, such that the polymer concentration was the most pivotal factor determining the topography of particles. 32) Decreasing the flow rate produced particles with more widely dispersed size ranges. High flow rate resulted in particles with somewhat uniform size distribution; however, a few fibers were observed.…”