A facile strategy for designing hollow-porous polymer microparticles with tunable structures

Biodegradable hollow-porous microparticles have shown great potentials in chemical and biomedical areas owing to their distinctive structural attributes. Herein, a simple but instructive strategy was proposed to construct hollow-porous polylactic acid (PLA) microparticles in one-step based on electrohydrodynamic atomization technology. Hollow-porous microparticles with fusiform, red blood cell and spherical shapes were successfully fabricated with production rates of 70 mg/h, 30 mg/h and 105 mg/h. A formation map in terms of flow rate ratio and PLA concentration was obtained to demonstrate the operating regions. Effects of key operating parameters were studied, showing that high voltage (11.4 kV−12.4 kV) and low PLA concentration conditions (2.5 %−3.5 %) are preferred to get well-structured particles. The evolutions of Taylor cone and atomization state were also explored experimentally and numerically to further understand the process. The prepared microparticles exhibit excellent sustained release performance and high encapsulation rate (>90 %). This strategy offers a satisfactory one-step method for preparing various structured hollow-porous polymer particles as drug carriers.