**4. Conclusions**

ASAs-loaded mPEG-PLA microspheres were successfully prepared using the W/O/W double-emulsion technique. The comprehensive results for the microspheres, including particle size, EE, LE, in vitro release and other tests, showed that mPEG10000-PLA microspheres performed excellently. The particle size of ASAs-loaded mPEG10000-PLA microspheres was 3.84 ± 0.30 μm, the EE was 75.12 ± 4.25%, and the LE was 5.17 ± 0.19%. The microspheres sustained release for 15 days in a simulated human environment, with beneficial biocompatibility at 40 μg/mL, and showed no toxicity to HL-7702 cells. It significantly inhibited auricle swelling in mice and pedal swelling in rats. These results indicate that mPEG-PLA is a carrier material suitable for controlled ASAs release.

**Author Contributions:** M.Y. and C.Y. conceived and designed the experiments; X.Z., Y.H., R.Y. and N.J. performed the experiments; X.Z., M.S. and H.L. analyzed the data; M.Y., H.L. and M.Y. contributed reagents/materials/analysis tools; X.Z. wrote the paper. X.Z. and H.L. contributed equally to this work.

**Funding:** This work was supported by the National Natural Science Foundation of China (Project Nos. 31460247, 81460542, 81760644), the Biodegradable Materials Innovative Research Team (in Science and Technology) at the University of Yunnan Province and the Innovation Team Based on Research and Application of Biological Functional Materials of Yunnan Minzu University (2017HC034), Yunnan Science and Technology Project - Major Science and Technology Specialities of Biological Medicine (2018ZF008). Graduate Innovation Foundation of Yunnan Minzu University (2018YJCXS268).

**Conflicts of Interest:** The authors declare no conflicts of interest.
