Synthesis Of Singlet Oxygen Nanoprobe For Use In Singlet Oxygen Fluorometric Sensing And In Photodynamic Therapy

At present,photodynamic therapy of cancer has attracted great attention because of its advantages of minimally invasive,repeated administration and low toxicity.For photodynamic therapy,photosensitizers can transfer energy to molecular oxygen and produce reactive oxygen species(mainly singlet oxygen),which leads to tumor cell apoptosis.However,the cancer hypoxia and the poor enrichment of photosensitizers limit the yield of singlet oxygen and therapeutic effects of photodynamic therapy.In order to detect the singlet oxygen production and monitor the progress of photodynamic therapy in real time,this thesis designes singlet oxygen nanoprobes doped with 1,3-diphenyl-isobenzofuran(DPBF).Based on the changes of absorption intensity and emission spectrum of DPBF,the singlet oxygen detection during photodynamic therapy can be realized.The specific research contents are as follows:(1)Firstly,DPBF doped oxygen nanoprobes are prepared by the reprecipitation method.The water solubility and stability of DPBF are improved owing to the coating of silica.The nanoprobes are characterized by transmission electron microscopy,dynamic light scattering particle size and absorption spectrum.The nanoparticles with good dispersibility are about 200 nm,and have a characteristic absorption peak of DPBF at around 426 nm.Indocyanine green(ICG)is selected as a photosensitizer,and the generation of singlet oxygen is characterized by the absorption intensity of nanoparticles under 808 nm laser irradiation.By analyzing DPBF doping concentration and laser irradiation power,it is found that the absorption peak of 15%-DPBF-NPs under 130 mW laser irradiation decreases obviously,and the absorption intensity of DPBF is quenched up to 86%.The results show that the nanoprobe has high sensitivity to singlet oxygen and is promising in the monitoring of singlet oxygen during photodynamic therapy.(2)In order to further improve the accuracy of singlet oxygen detection during photodynamic therapy,this thesis designs a kind of multifunctional nanoparticles which integrated photosensitizers ICG and singlet oxygen indicator DPBF at the same time.Firstly,the polymer hybrid nanoparticles doped with DPBF and reference material PFP as energy donator are prepared,and then indocyanine green is attached on the surface of polymer nanoparticles by electrostatic action to obtain ICG-DPBF-PFP NPs.ICG-DPBF-PFP NPs is proved to have high singlet oxygen yield by commercial SOSG method.At the same time,the ratiometric fluorescence of DPBF and PFP has high singlet oxygen sensitivity.The nanoprobe has high stability and good biocompatibility,and can be efficiently internalized into cell.The viability of HepG2 cells treated with ICG-DPBF-PFP NPs under 808 nm laser irradiation are detected by MTT and Live/Dead staining.It is found that the viability of tumor cells decreases with the increase of irradiation time,indicating that nanoparticles can induce apoptosis of cancer cells through photodynamic therapy.In addition,in the process of photodynamic therapy,the production of singlet oxygen can be detected in real time and the effect of photodynamic therapy can be evaluated depend on the change of DPBF luminous intensity under different treatment parameters.Comparing with the results of MTT method,it is proved that DPBF method can monitor the effect of photodynamic therapy in real time.We envision that the intelligent therapeutic platforms integrated of minimally invasive PDT with intracellular singlet oxygen feedback will largely facilitate the development of efficient and accurate photodynamic therapy.