Bimodal　mesoporous　silicas　(BMMs)　have　been　proved　to　be　a　good　drug-loaded　carrier.　However,　it　did　not　provide　stimuli　sensitivity　or　controlled　release　performance　yet.　In　the　present　work,　a　＂smart＂　mesoporous　silica-based　pH-dependent　[poly(methacrylic　acid)]-silica　hybrid　nanoparticles　(P/NN-BMMs)　drug　delivery　system　was　developed　and　evaluated　with　ibuprofen　(IBU)　as　a　model　drug.　P/NN-BMMs　were　prepared　by　coating　poly(methacrylic　acid)　(PMAA)　onto　amino-modified　surface　of　BMMs　via　the　graft　to　strategy.　The　structure　and　texture　of　resultant　hybrid　nanoparticles　were　determined　with　X-ray　diffraction,　scanning　electron　microscopy,　transmission　electron　microscopy,　Fourier　transform　infrared,　thermogravimetric　analysis,　N-2　sorption　isotherms,　and　elemental　analysis.　The　PMAA　acts　as　a　molecular　switch　to　achieve　controlled　drug　release　and　the　amount　of　grafted-PMAA　can　remarkably　affect　its　performance.　The　drug-loading　rate　is　decreased　markedly　with　the　increasing　of　the　amount　of　grafted-PMAA,　meanwhile,　the　drug-loading　kinetics　on　P/NN-BMMs　fits　Korsmeyer-Peppas　model.　In　addition,　the　drug-release　amount　from　drug-loaded　P/NN-BMMs　is　pH　dependent,　showing　an　increasing　tendency　with　the　increase　of　pH　value.　(C)　2015　Wiley　Periodicals,　Inc.　and　the　American　Pharmacists　Association