Synthesis Of Sevetal Inorganic Nanomaterials For Biomedical Applications

In this dissertation, versatile methods have been used to design multifunctionalbiocompatible and biodegradable nanomaterials. The multifunctional systems havebeen used for gene therapy, drug delivery, photothermal therapy, flurescent imaging,and magnetic resonance imaging (MRI). The therapeutic and diagnostic effects havebeen investigated in cells and animals. The main results can be summarized asfollowing:1. Superparamagnetic CaCO3mesocrystals have been synthesized to deliverAu–DNA nanoparticles and DOX as a multidelivery system (MDS) for cancer therapy.The porous CaCO3particles are able to encapsulate functional nanoparticles andmolecules for multiple applications. The superparamagnetic CaCO3 , which acts as acarrier, demonstrates its advantages for successful transfection in gene and drugdelivery in vitro. The multistage delivery approach and biodegradability propertiesprovide protected and enhanced targeted co-delivery of gene and drug in tumor tissuesof mice.2. A versatile selected etching strategy has been designed for synthesizingmesoporous hollow or core-shell structures. This mild approach for preparing hollowand core-shell structures with mesoporous silica shells is based on the porous CaCO3nano-templates. The versatility of this method is demonstrated by encapsulatingquntum dots, Fe3O4@silica and Au nanoparticles for the formation of hollowmesoporous silica nanospheres, Fe3O4@silica@mesoporous silica (MS) and Au@MS.This strategy could be generally applicable to encapsulate many other functional coreswith diameters smaller than the pore sizes of CaCO3 nano-templates. Thebiocompatibility, photothermal property and MRI application of these products havebeen explored. Furthermore, the potentialities of these hollow or core-shellnanospheres in biomedical application of drug/gene delivery, photothermal therapyand diagnosis can be expected.3. A mild approach has been developed for preloading DOX in hollowmesoporous silica (HMS) spheres by using porous CaCO3 spheres as templates. Withbiocompatible mesoporous silica shell, the DOX in HMS@DOX hollow spheresexhibit greatly enhanced therapeutic effects over the drug itself towards tumor cell.This might be caused by the protection of DOX extracellular by HMS@DOX, the pH-sensitive release and the enhanced intracellular delivery. The approach is suitablefor preloading drugs that would be resistant to the ammonia solution used for silicaformation and the weak acidic solution used for CaCO3 dissolution. Furthermore, theHMS@DOX has great potential application in cancer therapy, which worth moreinvestigations in the future.