Synthesis And Applications Of Organic-inorganic Hybrid Nanoprobes In Tumor Imaging/Photothermal Therapy

Photothermal therapy（PTT）is a new type of non-invasive tumor treatment technology.It converts the energy of near-infrared laser into thermal energy through photothermal probes,generates high temperature and kills tumor cells at the lesion effectively.The introduction of imaging technology in photothermal therapy can increase the efficiency and accuracy of photothermal therapy.Therefore,nano-scale photothermal probes with both therapeutic effects and multi-modality imaging functions have became a research hotspot in tumor diagnosis and treatment.Inorganic nanoprobes and organic nanoprobes both have some disadvantages.For example,most of inorganic nanoprobes are nonbiodegradable and contain heavy metal elements.The organic nanoprobes have poor photothermal stability and can not realize nuclear magnetic resonance imaging and computed tomography imaging.Organic-inorganic hybrid nanoprobes make full use of the versatility（optical,acoustic,electrical,magnetic and thermal）and thermal stability of inorganic nanomaterials,and expand multimodal imaging technology.Therfore,it could greatly improves its sensitivity in tumor imaging.In addition,organic-inorganic hybrid nanoprobes have good biocompatibility and specificity,significantly improve the accuracy of tumor treatment,and reduce biological toxicity due to the introduction of organic nanomaterials.The organic-inorganic hybrid nanoprobes have the characteristics of strong absorption in the near-infrared region,good biocompatibility,low biological toxicity and good photothermal stability,and have attracted more and more attention.This paper reviews the development and applications of organic/inorganic nanocomposites in biological imaging and photothermal therapy.The folic acid（FA）modified polypyrrole-gold（PPy-Au-PEG-FA）nanoprobes and gadolinium modified Bi₂S₃@polydopamine(Bi₂S₃@PDA-Gd^Ⅲ)nano-composites have been synthesized in this thesis.Both of them showed good biocompatibility and strong absorption in the near infrared region.Besides,a series of biological studies are carried out.1.The PPy-Au NPs which have strong absorption in the near infrared region was constructed by combining the PPy NPs with Au NPs based on the electrostatic selfassmble technique,and then the FA molecules were modified on the nanomaterial by the functional PEG.The photoacoustic imaging and CT imaging properties and the photothermal conversion efficiency of the nanocomposite probes were examined.The cytotoxicity and photothermal cancer therapy in vitro of the nanocomposite probes were also investigated.Finally,the in vivo bioimaging and photothermal therapy properties of the nanocomposite probes have been evaluatedon Hela nude mice model.Studies have shown that the composite material is expected to become a nanoprobe for CT/photoacoustic imaging multimodality imaging and photothermal therapy.2.The Bi₂S₃@PDA-Gd^ⅢNPs composite nanoprobes were synthesized by polymerization of PDA on the Bi₂S₃ NPs,and then load the Gd^Ⅲions by the coordination between the-OH on the surface of PDA and Gd^Ⅲions.The in vitro photoacoustic imaging,CT imaging,magnetic resonance imaging properties of Bi₂S₃@PDA-Gd^ⅢNPs were examined.The photothermal conversion,the cytotoxicity and photothermal cancer therapy in vitro of the nanocomposite probes were also investigated.At last,the in vivo multimode bioimaging and photothermal therapy properties of the nanocomposite probe were evaluated on Hela nude mice model.Studies have shown that the composite material is expected to become a nanoprobe for CT/MRI/photoacoustic imaging multimodality imaging and photothermal therapy.