Study On Preparation And Anti-tumor Properties Of Cobalt Sulfide-based And Carbon-based Nanomaterials

Despite the rapid development of biomedicine,cancer remains one of the major malignant diseases that threaten human life.Due to the inevitable toxic side effects and limitations of traditional anti-tumour therapies(chemotherapy,surgery and radiotherapy),the development of new,efficient and safe anti-tumour modalities has become an important part of research in this field.Light therapy,as a temporally and spatially controlled and minimally invasive treatment,has gained much attention.In addition,chemodynamic therapy is becoming a hot topic in anti-tumour research because of its high selectivity,specificity and biosafety by modulating the tumour microenvironment to achieve tumour growth inhibition.To further enhance the anti-tumour effect,in this thesis,we focus on transition metal cobalt sulphide based and carbon-based nanomaterials with broad absorption in the NIR-II region as the main object of research and synergise phototherapy with chemodynamic therapy to investigate their anti-tumour properties and summarise the mechanism of action,to provide theoretical support for the development of highly effective anti-tumour nanoparticle.The specific research contents are as follows:(1)Jauns Co₉S₈@C@PEG nanoparticles were synthesized by hydrothermal method.Through the morphology characterization and property testing,it was found that the material has good light absorption ability in the NIR-II region,and the photothermal conversion rate can reach 51.5%,as well as good photothermal stability and photothermal imaging ability.In addition,it can produce reactive oxygen species under nil-II light conditions to achieve photodynamic therapy.Due to the Fenton-like catalytic capacity of cobalt ions,the material exhibits catalase and peroxidase activities,which can catalyze the formation of O₂ and hydroxyl radical(·OH)from overexpressed H₂O₂ in the tumour,which not only alleviates tumour hypoxia but also achieves chemodynamic therapy.Given the heterostructure of Co₉S₈@C@PEG,photogenic charge separation can be effectively promoted,and the performance of chemodynamic therapy and the activity of nano-enzyme can be significantly improved.The nanomaterial can be used for in vivo MRI analysis because it contains Co element with 3d unpaired electrons.Therefore,Co₉S₈@C@PEG nanomaterials have realized the integration of collaborative phototherapy and chemodynamic therapy guided by nuclear magnetism and photothermal imaging,showing a good tumour inhibition effect.(2)The ultrathin Mo S₂ nanosheets were synthesized by hydrothermal method,on which Co₃S₄ nanodots with high dispersion were prepared,and Mo S₂/Co₃S₄@PEG nanostructures were synthesized.The nanocomposite has a high capacity for light absorption and photothermal conversion(39.8%)in the NIR-II region.Combined with the analysis of energy band structure,it was found that the nanocomposite had specific Z-Sheme charge transfer characteristics,retained high redox capacity of each component,and realized NIR-II photostimulated water decomposition to produce oxygen and reactive oxygen species.It not only alleviates tumour hypoxia but also improves photodynamic therapy performance.In addition,the catalase and peroxidase activities of the nanocomposite can further supplement oxygen and increase the concentration of hydroxyl radical in the tumour area to achieve tumour inhibition.Mo S₂/Co₃S₄@PEG nanocomposite have become a nano-integrated platform for synergistic therapy(phototherapy and chemodynamic therapy)under the guidance of dual-mode imaging(MRI and PI),showing good anti-tumour effects(3)The synthesis of nitrocarbon dot nanoparticles was confirmed by a series of structural characterisations,which successfully introduced a large number of-NO₂functional groups.The carbon nanoparticles have a high capacity for light absorption and photothermal conversion in the NIR-II region(27.6%).It is also capable of producing reactive oxygen species under NIR-II light for photodynamic therapy.In addition,it generates NO in the presence of GSH,leading to tumour vasodilation and enhanced oxygen transport.At the same time,NO produces ONOO^-radicals with higher toxicity to kill tumour cells through in situ binding of reactive oxygen species.Cellular experiments combined with mouse experiments have confirmed the good anti-tumour effect of this in situ NO-releasing and synergistically enhanced phototherapy nanosystem.