| Mesoporous silica nanoparticles(MSNs) have gained a significant interest due to their tunable particle size, stable framework, uniform pore size, high surface area, biocompatibility and unique porous structure. In the past decades, from the rise of the successful preparation of the MCM-41to various mesoporous silica materials obtained,this new species ofordered mesoporous silica molecular sieveshas exhibited a high potential acting as adsorbents, catalysts, therapeutic and diagnostic medical agents.In this thesis, the broad application of MSNs was discussed through prospects consist of three parts:morphological control, functional surface modification for control release and application in treating dentin hypersensitivity.Mesoporous silica with various species of morphologies were obtained using binary cationic-anionic surfactant as template after a facile hydrothermal treatment. CTAB and SDS were selected as cationic and anionic structure direct agent respectively. Mechanism of morphological control during this process was investigated by regulating the molar ratio of SDS/CTAB. Formation of the different stable morphologies were attributed to changes of the packing parameter which derived from the structural transition of SDS/CTAB assembly from micelle to bilayer commitment to the ascending ratio of SDS. This result plays a crucial role in guiding orientation synthesis using binary surfactants as structural direct agents.A relatively simplistic and adjustable approach was taken to synthesize MSNs with a thin controllable solid silica-cap(sSiO2) outer layer which prevented unwanted degradation for controlled drug release.Ibuprofen(IBU) was loaded into the MSNs (IBU@MSN) and used as the model cargo to acquire the release profiles. Despite the structural variations that resulted from different condensation rates, the sSiO2was shown to degrade slower than the MSN core due to its significantly lower specific surface area exposed to medium solution, which in effect acts as an efficient inorganic gatekeeper.The degradation rate of the sSiO2capping layer was found to directly correlate with the film thickness and allowed for the controlled release of loaded IBU. Additionally, calcium ions (Ca2+) which normally follow a burst release profile in water were loaded and used to further evaluate the efficacy of this system. This sSiO2-capped degradation strategy for controlled release could easily be extended to other pH or temperature responsive MSN systems and applications.The occlusion of dentinal tubules is considered to be an effective strategy to treat dentin hypersensitivity. This in vitro study introduced MSNs for tubular occlusion to achieve deeper sealing. Further, MSNs with independently encapsulated calcium and phosphates (as calcium and phosphate sources)(Ca2+/PO43-@MSNs) were introduced to achieve improved efficacy of tubular occlusion and remineralization. MSNs or Ca2+/PO43-@MSNs were proportionally mixed with distilled water to make their respective desensitizing slurries, which were used to treat dentin surfaces. The efficacy of tubular occlusion was evaluated using scanning electron microscopy (SEM) images and an image analyzer, and compared with that achieved with Green-OrTM—a commonly used desentizer. The results demonstrated that both MSNs and Ca2+/PO43-@MSNsalmost completely occluded dentinal tubules and formed a deeper seal which penetrated about83.5μm deep into the dentinal tubules. Significant differences in tubular occlusion were observed between Green-OrTM densitizer and MSNs or Ca2+/PO43-@MSNs. The novel MSNs-based nanomaterials showed great potential as a treatment option for dentin hypersensitivity... |
PDF Full Text Request