Synthesis of discrete and dispersible hollow mesoporous silica nanoparticles with tailored shell thickness for controlled drug release

By employing poly (tert-butylacrylate) (PTBA) nanospheres as the dissolvable core templates, we develop a new method to synthesize hollow mesoporous silica nanoparticles (HMSN). Both the PTBA core and the structure-directing surfactant, cetyltrimethylammonium bromide (CTAB), can be easily and synchronously removed through solvent extraction in ethanol, which ensures the complete structure and ideal dispersibility of the products compared with the previous template synthesis that often needs calcination to remove the templates. Given that hollow core diameter and shell thickness are the key properties of HMSN, the hollow core diameter and shell thickness can be tailored precisely. In addition, as novel inorganic nanomaterials with a tuned structure, HMSN show notable biocompatibility and efficient doxorubicin (DOX) loading. In in vitro tests, the release rate of DOX-loaded HMSN exhibit a surprising shell-thickness-dependent and a pH responsive drug release character, suggesting that HMSN are a very promising drug delivery system for shell-thickness-controlled drug release. The results of intracellular tracking and cytotoxicity assays further demonstrate the potential and efficiency of HMSN as a drug delivery system.