Mw of organic phase with different mixing procedures. Group a: only PLGA; group b: PLGA was dissolved in EA; group c: PLGA was dissolved PLGA in EA and BA; group d: PLGA and NTX were dissolved together in the mixture of EA and BA; group e: PLGA was dissolved in EA, followed by the addition of NTX, stirring for 5 min, and finally the addition of BA; group f: PLGA was dissolved in EA, followed by the addition of BA, stirring for 5 min, and finally, the addition of NTX; group g: NTX was dissolved in BA, followed by the addition of EA, stirring for 5 min, and finally, the addition of PLGA; group h: PLGA was dissolved in EA, NTX was dissolved in BA, and the two solution were mixed. EA: ethyl acetate, BA: benzyl alcohol. Compared with group a, *p < 0.05.