"Graft to" Synthesis and Ibuprofen-Loading Performance of pH-Sensitive PMAA-Silica Hybrid Nanoparticles with Controlled Bimodal Mesopores.

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, N2 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.