Objective      To explore the preparation conditions of poly(DL-lactide-co-glycolide) (PLGA) nanoparticles

and validate the entrapment efficiency and activity of basic fibroblast growth factor (bFGF) loaded by PLGA nanoparticles.       Methods      Bovine serum albumin (BSA)-loaded PLGA nanoparticles were prepared with a double emulsion method. First

the effects of the concentration of PLGA

mass ratio of PLGA and BSA

volume ratio of water phase and oil phase

and type of internal water phase on the particle size and entrapment efficiency were studied. Then the optimal conditions were selected to prepare bFGF-loaded PLGA nanoparticles

and the activity of bFGF was validated by proliferation of mesenchymal stem cells (MSCs).       Results      Under the optimal conditions

the entrapment efficiency of BSA-loaded PLGA nanoparticles was 70.0%

the particle size was 373±12 nm

and the Zeta potential was 27.1±0.6 mV. The protein was sustained-released

and the phenomenon of burst release was not obvious. Biological activity of bFGF loaded by PLGA nanoparticles was maintained

and the bFGF-loaded PLGA nanoparticles could better promote the proliferation of MSCs than bFGF solution.       Conclusion      PLGA nanoparticles prepared with the double emulsion method can be used to load growth factors to control their release and maintain their biological activity.