Metal-phenolic Coordination Oligomeric-embedded Biodegradable Silica Nanoparticles For The Drug Carriers And Catalyst

In this dissertation,biodegradable silica nanoparticles were designed as drug carrier and catalyst,which were based on doping metal-phenolic coordination oligomers(MPCOs)into SiO2 networks.The paper is divided into four chapters:The first chapter was introduction.The synthesis methods of silica nanomaterials and polyphenols-metal nanomaterials were introduced,with their application in nano-biomedicine and catalysis.In addition,the basis and significance of thesis were briefly discussed.In chapter two and three,using the strong coordination ability between polyphenol molecules(TA and EGCG)and metal ions,biodegradable SiO2 nanoparticles were synthesized by doping MPCOs into SiO2 networks,which can increase the silica porosity and weaken the density of silica through the hydrogen-bond interaction of phenolic hydroxyl and silanol.Results from in vitro and in vivo degradation experiments demonstrated that the prepared silica nanoparticles could be degraded in acid or intracellular condition within 7 days.The released polyphenol molecules can play the assistant therapy role and the released metal ions could be used as imaging reagent.Cytotoxicity experiments showed that when the photosensitizer Ce6 or DOX were used as loading model drugs,all the inhibition rate toward cancer cells could be reach to 75%.Data from in vitro magnetic resonance imaging experiments showed that after degradation with pH=5.0+10 mM GSH,the r2 value of SiO2-TA-Mn nanocomposites was up to 50.08 mM-1·S-1.Therefore,all the above results indicated that biodegradable silica nanocomposites could be synthesized by doping MPCOs into SiO2 networks.The obtained nanocomposites can be used as potential drug carriers because of their degradability,high inhibition of cancer cell and simple synthesized method.In chapter four,using the reducing ability of hydroxyls from silica and polyphenol,the uniform monodispersed Au nanoparticles were synthesized in situ on the surface and internal pores of SiO2-TA-Fe nanoparticles.TEM,SEM and other means were used for characterization.Furthermore,the obtained Au-SiO2-TA-Fe nanocomposites were applied as catalyst in selective hydrogenation of 4-nitrophenol(4-NP).The results showed that the as-prepared Au-SiO2-TA-Fe nanocomposites exhibited excellent catalytic activity and stability in the catalytic reduction reaction of 4-nitrophenol due to the narrow size of Au nanoparticles.The catalytic efficiency could be 90%in 18 minutes.After 5 successive cycles of reactions,no obvious change could be seen in nanocomposites and the conversion still reached over 85%.