Synthesis and characterization of nanofibrous hollow microspheres with tunable size and morphology via thermally induced phase separation technique

Abstract

In this paper, we present a facile thermally induced phase separation (TIPS) technique for the synthesis of size and morphology controllable poly(L-lactic acid) (PLLA) nanofibrous hollow microspheres (NHMs). The effects of propanetriol (PT) volume, polymer concentration, dropping rate, stirring speed and addition sequence on the physical properties of NHMs including particle size and surface morphology were systematically investigated. The results revealed that the obtained NHMs became more round in shape and more uniform in size with the increase of the PT volume. When the concentration of polymer solution was increased to 4%, the obtained NHMs showed a homogeneous nanofibrous structure, while their size became bigger and more uniform than those of prepared in lower polymer concentrations. The increased dropping rate of PT resulted in the packed nanofibrous structure and decreased microsphere size, whereas the increased stirring speed led to a reduced microsphere size. The uniformity and morphology of microspheres are also strongly influenced by the addition sequence. Furthermore, the in vitro cytotoxicity assay demonstrated that NHMs possess good biocompatibility. As a result, the synthesized NHMs would have significant potential in a variety of biomedical applications such as drug delivery and tissue regeneration.