Preparation Of Mesoporous SiO₂/Polymer Functional Multilayer Films And Their Drug Sustained Release Effect

The stable organic-inorganic composite multilayer films structure was prepared by layer-by-layer self-assembly(LbL)technique combined with covalent cross-linking method and its application in the field of protease immobilization was explored.In the dissertation,the “nano-net” superstratum strategy is developed to stabilize layer-bylayer films that incorporate nanoparticles.The superstratum immobilizes silica,magnetic nanoparticles or peptides and at the same time is permeable to small molecules.In addition,layer-by-layer self-assembly technique has also been used to prepare mesoporous silica core-shell nanoparticles containing PAA/PAH,and to study the application of nanoparticles in the field of drug sustained release and magnetic resonance.(1)The mesoporous silica material film acts as an inorganic layer of the support film,which can keep the morphology of the multilayer film from being damaged by adverse environments such as strong acid,strong alkali and strong oxidizing.The strategy does not directly cross-link the nanoparticles and polymers in the adjacent layer,thus circumventing the tedious processes of surface modification of the nanoparticles or polymers.A model drug,methylene blue,is then loaded in large amounts due to the porous structure of the silica particles,and could be released in a delayed manner up to 55 h.The retention strategy of the protein effectively retains the catalytic function of the protein,and the multilayer structure is sufficient to withstand the foaming catalytic reaction and the protein can be reused and immobilized.The spatiotemporal retention of proteins could be adjusted by varying the number of capping layers.It has been demonstrated that protein-based interfacial layers can be used to construct catalytically active interfaces and as an integrated motion device to drive a macro-floating device.(2)Mesoporous silica nanoparticles embedded in the multilayer membrane of covalent cross-linking can retain the FITC(fluorescein isothiocyanate)-labeled peptide,the space-time retention of the peptide may vary with the number of multilayers.It was demonstrated that the release rate of guest molecules such as tyrosine and adamantane modified peptides can be controlled by the number of layers of mesoporous silica nanoparticles and hyaluronic acid-cyclodextrin multilayer film.The layer-by-layer technique was exploited to adjust the magnitude of the host-guest interactions between adamantane and cyclodextrin.The effect depends on numerous complex and changeable growth profiles of the films and the number of bilayers.These composite films of mesoporous silica nanoparticles and hyaluronic acid-cyclodextrin(HA-CD)were constructed to load the fluorescent dyes and peptides.The release rates of these molecules would decrease with an increase in the number of layers.The laser scanning confocal microscope was utilized to obtain the diffusion coefficient of fluorescein isothiocyanate.Hybrid films could be applied to increase the loading of different kinds of molecules and could also be integrated into the lamination to delay the rate of release.(3)The monolayer polymer film cap is enough to prevent the release of Rhodamine 6G.Four layers of polymer film can prevent smaller molecules from releasing,such as Magnevist.Molecular releases of different sizes can be controlled by adjusting the number of layers of the multilayer cap.Multilayer cap can be damaged by ultrasound or high intensity focused ultrasound.After closing the ultrasound probe before the cap is destroyed,the drug molecule will release for a period of time and then stop releasing.