Preparation of natural pyrethrum-polylactic acid microspheres with different particle sizes and surface morphology

Controlled-release technology has been widely studied in the field of medicine, but it is rarely used in pesticides. The objective of this study was to obtain pyrethrin-polylactic acid microspheres with different particle sizes and morphologies. By adjusting the concentration of polylactic acid and the rotation speed, a series of microspheres can be prepared simply and efficiently by using the single emulsion-solvent evaporation method. The result of laser particle size analyzer showed that the average diameter of the microspheres ranged from 13.5 to 142.4 mu m. The FESEM observation revealed that the obtained microspheres were spherical with pores on the surface. And as the particle size decreases, the area of the surface pores becomes larger and shallower. The spectrum of FTIR indicated the presence of pyrethrin in the prepared microspheres. (C) 2020 Elsevier B.V. All rights reserved.