Factors affecting the co-axial electrospraying of core–shell-structured poly( d , l -lactide- co -glycolide) microparticles

Abstract Co-axial electrospraying is a simple and versatile process, achieving liquid atomization through electrical forces, to produce core–shell-structured nano/microparticles. Despite its advantages in terms of preparing particles with sizes ranging from 300–500 µm down to 50–70 nm, the optimization of the co-axial electrospraying process remains a challenge. In this study, we investigated experimentally the effects of processing parameters on the size distribution of co-axially electroprayed poly( d , l -lactide- co -glycolide) (PLGA) microparticles. The effects of various parameters, including voltage, flow rate ratio, travel distance, and polymeric concentration, were examined using a factorial experimental design. It was found that the particle size of electrosprayed core–shell microparticles decreases with the voltage and travel distance, and it increases with the flow rate of the solutions and the PLGA concentration in the solutions. Furthermore, to verify the existence of proteins in the co-axially electrosprayed microparticles, PLGA was used as the shell, and recombinant enhanced green fluorescent protein (reGFP) was employed as the core material. Transmission electron microscopy (TEM) and laser scanning confocal microscopy (LSCM) were employed to confirm the core–shell structure of the microparticles. The experimental results demonstrated that under optimum conditions, core–shell-structured microparticles can be successfully prepared using a protein with high activity at the core.