Design And Preparation Of Multifunctional Nanomaterials For Biomedicine Application

The design and assembly of multifunctional nanomaterials and their application inbiomedicine have attracted much attention in the multi/interdisciplinary subject intersected bychemistry, materials and biological medicine. Controlled assembly of various building blocksat the nanoscale level is the key factor to realize the combination of analysis, diagnosis andtherapy, controlled and image drug release. Thus, in this thesis, several types of fluorescentnanoparticles, multifunctional nanomaterials, and controlled drug release systems with variousbuilding blocks have been designed and prepared, such as silica, upconversion nanomaterials,gold particles, organic dyes, conjugated polymer, photosensitizers, and drug molecules etc. Theresults are summarized as follows:1. To combine the complementary strengths of nonporous and mesoporous silicananoparticles, uniform and monodisperse core-shell nano-vehicles comprising a nonporoussilica core and a mesoporous silica shell were designed and synthesized. Meanwhile, aone-step self-assembly process which allowing photosensitizers molecules to be physicallyentrapped inside the hexadecyltrimethylammonium bromide （CTAB） micelle channels ofsilica mesopores was developed, which enhanced the efficiency of production of1O2。2. A novel multifunctional core-shell nanocomposite material with a nonporous fluoresceinisothiocyanate （FITC） doped silica core and a mesoporous silica shell containinghematoporphyrin （HP） was developed. This architecture allowed simultaneous fluorescenceimaging and photosensitization treatment. The photosensitizer molecules are covalentlylinked to the mesoporous silica shell and exhibited excellent photo-oxidation efficiency.The mesoporous silica nanovehicle acted not only as a carrier for the photosensitizers butalso as a nanoreactor to facilitate the photo-oxidation reaction. The doping of FITC into thenonporous core was well protected from the damage by singlet oxygen, and theirfluorescent label capability was demonstrated by cell imaging experiments.3. A unique assembly approach was developed to fabricate conjugated polymer andphotosensitizer-doped mesoporous silica nanoparticles with effective F rster resonanceenergy transfer （FRET） frompoly[（9,9-di（3,3’-N,N’-trimethylammonium）-propylfluorenyl-2,7-diyl）-alt-co-（1,4-phenylene）]（PFP） to porphyrin-based photosensitizers （PSs）. PFP and silica nanoparticles formed a complex through electrostatic interactions, and efficient energy transfer from PFP toporphyrin-based PSs occurred upon irradiation. PS-doped mesoporous silica nanoparticlesshowed three-to four-fold enhanced emission with the excitation of the maximumabsorption wavelength of PS in the presence of PFP in comparison to the case without PFP.4. A novel pH-responsive hybrid nanoparticles was designed and prepared by using acetalgroup linked poly（N-isopropylacrylamide） capped fluorescent mesoporous silicananoparticles which comprise of a RuBpy doped silica core. The hydrolysis of acetal linkerat acidic environment made the poly（N-isopropylacrylamide） work as a gatekeeper tocontrol the release of guest molecules from mesoporous silica under different pH’s.Fluorescence imaging also demonstrated that pH-responsive hybrid nanoparticles could beefficiently taken up and activated by Hela cells.5. A versatile triggered release system was designed and prepared by capping thecyclodextrin-modified gold nanoparticle （CD-Au） onto the mesoporous silica （MS）, whichcombine the merits of multidrug loading and sequential release by light initiation orcompetitive binding. Cyclodextrin-modified gold nanoparticle anchoring on the surface byforming inclusion complexes with quinoline/adamantine linked to MS by o-nitrobenzylester. Moreover, CD-Au acted not only as gate to lock RuBpy molecules in the pores ofMS, but also provide abundant CDs as carriers to deliver fluorescein. The release ofmultidrug from mesoporous silica-based nanocontainer was demonstrated by cell imagingexperiments.6. A series of upconversion luminescence materials （NaYF₄: Yb, Er） with differentmorphology were synthesized by the hydrothermal, solvethermal and thermaldecomposition approach. The ratio of green to red emission intensities were related to thecapping ligand, phase transition and crystallite size. In addition, NaYF₄: Yb, Tm and goldcomposite were also prepared via host-guest interaction between cyclodextrin and oleicacid, which interacted with cyclodextrin on the surface of NaYF₄: Yb, Tm.