A new method was developed to fabricate polymeric microspheres which were composed of homogeneous nanofibers by means of the combination of heterogeneous nucleation and controlled hydrolysis.According to the role of heterogeneous nucleation of multimethyl-benzilidene sorbitol (TM6) and its influences on the crystalline morphology of poly(butylene adipate)(PBA)

the PBA microspheres were first fabricated by means of single emulsion solvent evaporation (O/W) or double emulsion solvent evaporation (W/O/W)

and then the influences of the nucleating agent TM6 on the morphological change of microspheres in the course of enzymatic degradation were studied.The results indicated that the PBA microspheres with porous structure were fabricated via the W/O/W method.The porous structure of microspheres is favorable for the diffusion of lipase buffer solution into the porous inner of microspheres

leading to the homogenous hydrolysis of PBA chains in microspheres

and finally resulting in the microspheres with nanofibrous structures.By means of W/O/W method

the PBA microspheres with homogeneous nanofibers in whole microspheres were fabricated when 3 wt% TM6 was added in PBA solution and the microspheres were degraded in lipase buffer solution for 5 h.The cell experiments revealed that the nanofibrous structure can greatly improve the adhesion

spread and in-growth of MG-63 cells on microspheres.These microspheres composed of nanofibers show great potentials for large-scaled cell proliferation in bioreactors.