Synthesis And Application In Biocompatible Nanomaterial Of Lanthanide-Titanium-Oxo Clusters

TiO2 nanoparticles could produce light toxicity and that destroy the cancer cells,so they can be used as photodynamic therapy(PDT)agents in biomedical fields.However,there are some limitations for such agents.Most of the preparation methods are complicated and the surface states of the photosensitizer(PS)molecules are difficult to be controlled.The stacking of the PS molecules on particle surface will cause self-quenching of the activity.Titanium-oxo-clusters(TOCs)are analogues of nano TiO2 but with uniform size,precise structures and high solubility.TOCs doped by metals at atomic level or modified by functional ligands can be used as precursors for preparation of nano TiO2 with predictable structures and unique properties.TOCs have been used in various applications.However,no biomedical research studies of such TOCs have been documented until now.As one of the branches of TOCs,lanthanide-titanium-oxo-clusters(LnTOCs)with photocatalytic and luminescent properties have attracted increasing attention over the past few years.On the other hand,multifunctional biomaterials with effective imaging system and photoinduced reactive oxygen species(ROS)system are desirable for effective PDT.Therefore,it is very necessary to develop a convenient method to prepare imaging and PDT-active nano TiO materials from LnTOCs.In this thesis,we emphasize the synthesis of novel LnTOCs and preparation of water stable nano particles using the LnTOCs to further investigate their application in biomedical fields.The main contents of the thesis are as follows:(1)In chapter 1,the current research of the water-soluble TOCs and LnTOCs were summarized;the applications of TOCs in biochemistry and the latest research progress of nano TiO2 as a photodynamic therapy(PDT)agent were introduced.The idea and significance of this work were expounded.(2)In chapter 2,three LnTOCs formulated as[Ln2Ti602(C204)4(NO3)2(O'Pr)20]'2HO'Pr(Ln = La'(1),Ce(2),Eu(3))were synthesized.The crystal structures and their degradation products(1'-3')were carefully characterized.1'-3' are Ln-TiO-C2O4 materials obtained by dealkoxy reactions.The improvements in photocurrent conversion and photocatalytic activity of dye-degradation are attributed to the synergistic effects of lanthanide metal and oxalate doping in TiO catalysis.(3)In chapter 3,three isostructural LnTOCs formulated as H2@[Ln2Ti8(?3-O)8(?2-O)4(AC)16]·24CH3CN·23H2O,Ln=Eu(4),Tb(5),Yb(6)were prepared by solvothermal method.The compounds are easily soluble in water forming the stable solution of the cluster aggregates(LnTOC-a).Using the fluorescent 4-a solution,high sensitivity and selectivity for biomolecule ascorbic acid were found.The work demonstrates also the excellent biocompatibility of 4-a.(4)In chapter 4,two novel structures of LnTOCs formulated as[Ln2Ti8(?3-O)6(Ac)18(O'Pr)8]·4CH3CN,Ln=Eu(7),Tb(8)were synthesized.Using EuTOC,water soluble fluorescent nano materials 7-n were obtained by a new explored organic-inorganic phase transfer technique.The 7-n solution showed selective fluorescence sensor properties for VB12.The 7-n has good biocompatibility and fluorescent labeling performance in HeLa cells.(5)In chapter 5,paramagnetic Gd3+was incorporated into TOC,compound 9 formulated as[Gd2Ti8(?3-O)6(Ac)18(O'Pr)8]·4CH3CN was prepared by solvothermal method.Photosensitizer,tetra(p-benzoato)porphyrin(TBP)was incorporated with the GdTOC and a red light excitable nano-aggregation,9-n-TBP were obtained.To evaluate the PDT efficiency,concentrations of 'O2 produced by 9-n-TBP and the toxicity for HeLa cells under red laser irradiation were examined.The results showed that the 9-n-TBP have the potential to be a PDT agent.Moreover,magnetic resonance imaging(MRI)showed that the image brightness of the material was comparable to that of commercial reagents.