Fig. 4. In vitro pH-responsive release of DOX from (A) PAA-POSS@DOX NPs (red) and PAA@DOX NPs (black) for 24 h in pH 5.0 and pH 7.4 PBA buffer solution, 37.5 °C and (B) extended drug release profiles of PAA-POSS@DOX NPs by changing the release medium to PBS (pH 7.4 and 5.0) for 24 h.