Preparation Of Bismuth-based Materials And Application In Phototherapy Guided By Multimodal Imaging

Photosensitizer-based therapy has been identified as a safer way to treat many cancer indications,mainly divided into two treatments: photodynamic therapy and photothermal therapy.Photothermal therapy is to ablate the tumor by local thermal injury,and photodynamic therapy is to cause targeted regional chemical damage to ablate the tumor.Before using laser irradiation,we need to determine the concentration of photosensitizer in the target area,and we can introduce imaging technology to solve this problem.And imaging technology can not only be used to determine the concentration of photosensitizer in the target area,but also provide more accurate diagnostic information,so as to achieve the integration of cancer diagnosis and treatment.Bi-based materials have high X-ray attenuation coefficient,near-infrared absorption capacity and good photothermal conversion efficiency,so the research of Bi-containing nanomaterials has been extended from optical,chemical and engineering fields to biomedical fields.However,its absorption wavelength is often in the first window of near infrared,which has some problems,such as low penetration depth,large energy dissipation and high toxicity to normal tissue,which limits the application of Bi-based materials in phototherapy.Therefore,the following two works have been carried out in this paper:(1)Mn Bi2S4@Au-PEG inorganic nanoparticles were synthesized by microwave-assisted solvothermal technology,and the nanoparticles have strong spectral absorption in the near-infrared first window and the near-infrared second window.Because the introduction of Au further improves his photothermal conversion efficiency and X-ray absorption ability.The experimental results show that the nanoparticles have good biological safety,have the potential to be used as contrast agents for CT and MRI,and have higher photothermal conversion efficiency when irradiated by 1064 nm laser.Therefore,this material can be used as a potential diagnostic reagent for CT/MRI-guided photothermal therapy under the second window of near infrared.(2)Bi2Se3@Cu2-x Se-PEG inorganic nanoparticles were synthesized by one-pot method.CT/MRI tests in vivo and in vitro show that they have good dual-mode imaging ability.The cell uptake experiment shows that the nanoparticles have good nuclear targeting ability and have the potential to improve drug resistance.Through the cytotoxicity experiment,it can be proved that the nanoparticle has a good effect in photodynamic therapy and photothermal therapy;through the cloning experiment,it can be proved that the nanoparticle has high X-ray absorption capacity and good radiotherapy effect.It was found that it could inhibit the growth of tumor when it was injected into mice by tail vein injection and irradiated with different power of 1064 nm laser and X-ray.Therefore,this material can be used as a potential diagnostic and therapeutic reagent for CT/MRI-guided phototherapy and radiotherapy under the second window of near infrared.