Emulsion-ultrasonic spray method to prepare polylactic acid microspheres

Polylactic acid (PLA) microspheres are widely used in drug delivery and bone repair, among other applications. Herein, an ultrasonic spray-assisted emulsion method was developed to prepare PLA microspheres. The key factor affecting microsphere formation—duration of ultrasonic spray circulation—was discussed, and the effect of polyvinyl alcohol (PVA) concentration on microsphere morphology was evaluated. Compared with the emulsion solvent evaporation method by mechanical stirring, microsphere preparation time was shortened from 5 h to approximately 1.5 h based on ultrasonic cavitation effect, which converted the emulsion into micro-atomized droplets and accelerated solvent volatilization. Using this approach, microspheres formed when the PVA concentration was increased to 3 mg/mL, and the particle size decreased with increasing PVA concentration. Moreover, PLA microspheres could construct spaces in favor of cell growth. Altogether, this new method provides technical assistance for the preparation of polymer microspheres for tissue engineering.