Design,synthesis And Photothermal Properties Of Conjugated Polymer Based On A Quinoxalinebenzotriazole Unit

Organic conjugated polymers,which are widely used in the fields of organic light-emitting diodes,together with organic solar cells and organic field-effect transistors and so on,gain their attention due to their structural diversity,functional integration,convenient synthesis and easy-to-adjust spectra.From the energy transfer process of organic molecules,the energy absorbed from the ground state of the organic molecule jumps to the excited state,which is a high energy unstable state,and internal conversion and intersystem crossing,and non-radiative transition.Generally,non-radiative transition will cause energy loss,which is unconducive to improve the performance of OLED and OPV devices.At present,photothermal therapy,a new type of tumor therapy,is emerging in the medical field.It is the use of materials in excited state to convert energy into heat through non-radiative transition,which makes the local temperature of the tumor rise,and ultimately kill the cancer cells,so as to achieve the purpose of tumor growth restriction or ablation.With the development of science technology,the research of photothermal therapy based on organic conjugated polymers is growing.However,the development of photothermal therapy is hindered by the poor photothermal conversion performance and complex structure of existing materials.In order to solve these problems,we designed a novel electron-withdrawing unit,triazoloquinoxaline,and its conjugated polymer,and prepared their water-soluble nanoparticles,which successfully achieved the photothermal therapy treatment of subcutaneous tumor in mouse.The specific research content is divided into the following two parts:(1)The design and synthesis of a new electron-withdrawing unit triazoloquinoxaline and its D-A conjugated polymer;The photophysical properties of the polymers were characterized by UV-Vis absorption spectra;The photophysical properties and photothermal conversion properties of the target polymer nanoparticles were studied by using the general nano coprecipitation method.Finally,PTzQI-BDT NPs can reach the PCE of 64.3%under 808 nm laser.The hydrodynamic diameter of PTzQI-BDT NPs is 90±22 nm,which means PTzQI-BDT NPs can easily get into cells.Besides,the high level photothermal stability of PTzQI-BDT NPs makes biological experiment possible.(2)The selected conjugated polymers were used for photothermal therapy at the cellular and animal levels.At the cellular level,we prove the extraordinary effect of photothermal therapy and cytocompatibility by cytotoxicity test,living/dead cell double staining experiment and flow cytometry experiment.At the vivo mouse level,the tumor-bearing mice were conducted to assess therapeutic effect of PTzQI-BDT NPs based on PTT in vivo by intratumoral injection.After irradiation with 1.0 Wcm^-2 808 nm laser for 5 min,the tumor in tumor bearing mice could be completely ablated,and there was no recurrence in the 16 day treatment cycle.Finally,H&E staining showed that PTzQI-BDT NPs have no obvious toxic or side effects on the main organs of mouse.