Magnetic mesoporous silica microspheres with thermo-sensitive polymer shell for controlled drug release

A controlled drug release system was designed based on the combination of three advantages into one entity, which was composed of Fe3O4 magnetic nanoparticle as the core, mesoporous silica as the sandwiched layer, and thermo-sensitive P(NIPAM-co-NHMA) copolymer as the outer shell. The hydrophilic comonomer content affected the volume phase-transition temperature (VPTT) of this composite microsphere and the behavior of the temperature-triggered drug release. Zn(II) phthalocyanine tetrasulfonic acid (ZnPcS4), a well-known photodynamic therapy (PDT) drug, was used as a model drug to assess the release system. The results demonstrated that the drug release behavior was dependent on the temperature and had a close correlation with the VPTT. Above the VPTT, the drug release rate was much faster than that below the VPTT, which showed a great potential application in tumor therapy.