Synthesis And Application In Tumor Therapy Of Bi-based Nanomaterials

In recent years,high-Z(high atomic number)nanomaterials with enhanced photoelectric and Compton effects have been widely used in enhancing the therapeutic efficiency of radiotherapy(RT).Essentially,high-Z elements interact with X-rays more than light elements(such as H,O,and N)to increase energy deposition and radiation hydrolysis near the nanomaterial.Bi,as element No.83 of the periodic table of elements,its X-ray attenuation performance is much greater than that of high Z elements such as Au and I,so it should have a better effect in enhancing the efficacy of radiotherapy.In addition,many Bi-based materials can be used as gastric drugs,so the biocompatibility of Bi-based nanomaterials is obvious to all,which lays a solid foundation for the use of Bi-based nanomaterials as radiosensitizers for tumor treatment.In this article,we synthesized two Bi-based nanomaterials,characterized their morphology,structure and physicochemical properties,and then verified the effectiveness of nanomaterials for tumor therapy at the cellular and living levels.The main research contents of this article are:(1)As we all know,the high radiation dose and the radiationresistance of tumor tissue is still a problem for radiationtherapy.Therefore,it is urgent to study effective and safe radiotherapysensitizers.In this paper,we synthesized Bi₂Se₃ nanosheets modified with PVP by pyrolysis method.It was found that the PVP-Bi₂Se₃ NSs have strong absorption in near infrared region and the solution has good photothermal conversion performance and photothermal stability under the irradiation of 808nm laser.It can be used for photothermal therapy of tumors.The photocurrent of semiconductor materials and the generation of reactive oxygen radicals(ROS)were studied under X-ray irradiation,and then we found that nanomaterials can absorb X-ray and generate electron-hole pairs,thereby promoting the generation of large amounts of ROS and enhancing radiation therapy.The PVP-Bi₂Se₃ NSs were used in synergy between PTT and RT.The detection of the ROS in the cell,DNA damage and cloning experiments have shown that they can effectively increase the damage of cellular DNA by producing more ROS and reduce the formation of cell communities.At the same time,PTT promotes blood circulation,enhances the uptake of nanomaterials,and thus enhances the efficacy of radiation.It can be used in mouse experiments to effectively inhibit the growth of tumors.The mutilfunctional radiotherapy sensitizer based on PVP-Bi₂Se₃ NSs not only can be used for photothermal therapy but also can enhance radiation therapy,and have good tumor treatment effects.(2)Tumor hypoxia is a vital factor affecting radiation therapy in which oxygen plays a critical role in tumor destruction.However,studies to relieve hypoxia have failed to achieve physical sensitization,making radiation therapy still dose-dependent.In this paper,the hydrothermal method is used to synthesize the defective multifunctional BiO_2-x nanosheets to overcome the hypoxia-induced radiation resistance while enhancing radiation therapy.On the one hand,high-Z element Bi enhances radiotherapy by depositing high-energy rays in tumors,and the photocatalytic activity of semiconductors can also produce more active oxygen radicals,especially superoxide anions(·O_2-).On the other hand,multifunctional nanosheets can decompose overexpressed H₂O₂ in tumors into O₂ to relieve hypoxia.Both in vivo and in vitro experiments show that the prepared T-BiO_2-x NSs can effectively inhibit tumor growth under X-ray irradtation.This article provides a simple but versatile nano-radiotherapy sensitizer that improves the efficacy of radiation while relieving tumor hypoxia,which has an absolute advantage over other reoxygenation systems.In summary,the two multifunctional Bi-based nanomaterials synthesized in this parper have good effects on tumor therapy,and provide new materials and approaches for the application of Bi-based namomaterials in tumor therapy.