Study On The Preparation Of PH Stimuli-Responsive Mesoporous Silica Nanocontainers And Properties For Controlled Release

Nanocontainers are nano-scale hollow materials, which have numerous properties in uptaking and releasing. As an ideal nanocontainer, mesoporous silica nanoparticles (MSN) have been investigated for the application in biochemical field, because of their large capacity, ease surface modification and excellent biocompatibility. Especially, MSNs-based responsive can regulate the release of encapsulated guest molecules by external stimuli, such as pH, temperature activity, photoirradiation and redox. Among these stimuli, pH activation has been researched widely. In this thesis, focusing on the construction of pH-responsive nanocontainers-carriers, we designed acidic and basic dual stimuli-responsive hollow mesoporous silica nanoparticles and investigated their preparation and controlled release properties of drug and corrosion inhibitor molecules, including the following aspects.The hollow mesoporous silica nanoparticles (HMSs) were prepared by using polystyrene microspheres (PS) as hard templates. The supramolecular nanovalves in the form of the bistable pseudorotaxane molecules were installed on the surface of the HMSs and achieved the acidic and basic dual stimuli-responsive release effects of guest molecules, including drug molecules, gemcitabine (Gem) and corrosion inhibitor molecules, benzotriazole (BTA) and caffeine (Caf). The morphology and structure of HMSs were characterized by scanning electron microscope/transmission electron microscope (SEM/TEM), X-ray diffraction assay (XRD), Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. The surface functionalization of HMSs was demonstrated by solid state NMR spectra (SS NMR), Fourier Transform Infrared Spectrometer (FTIR), thermogravimetric analysis (TGA), elemental analysis and Zeta potential. The release performances of guest molecules at different pH values were monitored by UV-vis spectrophotometer. The results showed that the intelligent nanocontainers constructed by the supramolecular self-assembly technology realized "zero premature release" at neutral condition and remarkable release at acidic or alkaline conditions. The specific controlled release characteristics make the intelligent nanocontainers to act as drug carriers in the organism realizing pH-responsive controlled release. Also as active components in the smart anticorrosion coatings, perceiving the localized acidification in the corrosion microanodic region and the localized alkalization in the corrosion microcathodic region, and releasing corrosion inhibitor molecules to prevent the spread of corrosion. Moreover, the HMSs could be improved the loading of the guest molecules to some extent by changing shell thickness and surface functionalization.