Fabrication Of Multifunctional Mesoporous Silica-based Nanomaterials For Bioapplicaiton

The rapid development of nanoscience and nanotechnology has greatly promoted the widely application of nano-materials in the field of biology and medicine. In recent years, mesoporous silica(m Si O2) nanomaterials caused widely attention in biomedical field due to their tunable pore sizes, the stability of the skeleton structure, easily modified internal and external surface and good biocompatibility, and their abundant pore can store a variety of drug molecules, which can be controlled released. In addition, m Si O2 as the body material, combined with the object of different functional materials, such as gold, silver nanoparticles, magnetic nanoparticles quantum dot, fluorescent molecular, target biological molecules have good developing prospects in fluorescence imaging, magnetic resonance imaging and drug targeting delivery.In this thesis, we synthesized multifunctional m Si O2-based nanoparticles and explored its role in biological applications such as drug transport, controlled drug release and so on.(1) Fabrication of fluorescent polyethylenimine(PEI) modified m Si O2 coated Fe3O4 yolk-shell nanocapsules as small interfering RNA(si RNA) carrier, which could specific silence the gene of β-acitin inside the Hela cells, achieveing the fluorescent tracer and magnetically guided si RNA delivery. The results indicated that our PEI-Fe3O4@fm Si O2 yolk-shell nanocapsules as si RNA delivery nanocarriers could efficiently deliver the si RNA into cytoplasm, and then the delivered si RNA could be released and effectively silence the targeted m RNAs.(2) We developed a simple, universal, green and mild method to synthesize m Si O2 coated Fe3O4 yolk-shell nanocapsules. First, a layer of PEI was coated on the surface of PEI-Fe3O4@m Si O2 core-shell nanoparticles. Then PEI-Fe3O4@m Si O2 core-shell nanoparticles were etched at 50 °C in water to get uniform PEI-Fe3O4@fm Si O2 yolk-shell nanocapsules. This method can be extended to the synthesis of nanocapsules with m Si O2 shell and different cores. After grafting targeted groups and loading anticancer drug(DOX), we tested the synergistic effect of specific chemical and magnetic targeting in liver cancer cells.(3) Poly(acrylic acid)(PAA) was assembled on the surface of Au nanoparticles to obtain Au-PAA Janus nanoparticles. Then, the TEOS was selectively hydrolyzed among the net of PAA to get small Si O2 nanoparticles, which accumulate to the m Si O2 nanoclusters. After that, Au branches were grown on the bare surface of gold to get octopus-type Au-PAA/m Si O2 Janus nanoparticles. As expect, PAA/m Si O2 has high drug loading and p H sensitivity. The drug molecular can be released in acid solution. Moreover, with 808 nm NIR laser irradiation, the drug release from the octopus-type Au-PAA/m Si O2 Janus nanoparticles can be promoted to reach dual-modle drug release. Finally, we have demonstrated the synergistic chemo-photothermal effect on cancer cells killing in vitro and in vivo.(4) Synthesis of Ag@m Si O2 nanoparticles was carried out in one pot to get uniform Ag@m Si O2 nanoparticles. Then, the surface was modified with specific acid-sensitive nanovalve to explore the synergistic effect of silver nanoparticles and drug molecules for the inhibition of Francisella Tularensis.