Construction And Evaluation Of Multimodal Imaging-Guided Photothermal Nanotheranostic Agents

Cancer remains the world’s most serious health problem.Multimodal imaging-guided photothermal therapy has shown great potential in cancer treatment through the integration of diagnosis and treatment.Therefore,nanotherapeutic agents with both therapeutic and imaging functions attract extensive attention.This thesis reviews the application and progress of functional nanomaterials in photothermal therapy and imaging of tumors.On this basis,three different nano-composites with photothermal conversion properties and imaging functions were designed and synthesized,and their applications in photothermal therapy and imaging of tumor cells were studied in vitro.The main contents are as follows:1.Co-precipitation method was used to prepare Fe₃O₄ nanoparticles.then polydopamine with good biocompatibility and photothermal conversion properties and gadolinium contrast agent in magnetic resonance imaging were modified onto the surface of Fe3O4 by layer-by-layer assembly.Fe3O4@PDA-NH2-DTPA-Gd nanocomposites with functions of T₁/T₂ dual-mode magnetic resonance（MR）imaging and photothermal therapy were prepared.The colloidal stability and cytotoxicity of Fe₃O₄@PDA-NH₂-DTPA-Gd nanomaterials were studied.Photothermal conversion properties and cell photothermal lethality of the nanomaterial were investigated.Finally,the MR imaging capability of the nanocomposite and the effect of in vitro cellular enhanced magnetic resonance imaging were explored.The results show that these nanocomposites are promising to serve as a multifunctional nanoplatform for cancer diagnosis and therapy.2.DTPA-OA of amphiphilic ligand was synthesized by amide reaction,and then chelated with gadolinium ion.Bi2S3-Gd nanomaterials were prepared by ligand exchange with hydrophobic Bi₂S₃ nanoparticles.A series of characterization results proved the successfully synthesis of Bi₂S₃-Gd nanomaterials.After that,the colliodal stability and hemolysis of Bi₂S₃-Gd nanomaterials were studied,the photothermal conversion performance and photostability of the nanomaterials were evaluated,and the cytotoxicity and cell photothermal lethality of the nanomaterials were investigated by MTT assay and living-dead cell staining method.Finally,the CT and MR imaging capabilities of Bi₂S₃-Gd nanomaterials were explored.The results showed that Bi₂S₃-Gd nanomaterials could be used as nanotheranostic agents for CT/MR imaging guided photothermal therapy of cancer.3.Hollow mesoporous silica coated bismuth sulfide（Bi₂S₃@hmSiO₂）nanomaterials were synthesized by hot water etching,and chemical drugs were loaded into the hollow mesoporous structure for the synergistic treatment of photothermal and chemotherapy.The photothermal conversion properties of the nanomaterials were investigated,and the drug loading and drug release capacity of the Bi₂S₃@hmSiO₂nanomaterials were studied.The results showed that Bi₂S₃@hmSiO₂ nanomaterials had a certain photothermal conversion effect,which will be further optimized to obtain better photothermal conversion ability and drug loading performance.