Cucurbit[7]uril Enhances Photosensitization Of Porphyrins In SH-SY5Y Cells

Objective:Study on the changes of TPOR combined with CB[7]and its effect on SH-SY5Y cells induced by photodynamic action.Methods:The structure of TPOR was characterized by ¹H HMR.The ultraviolet-visible light absorption spectrum and the fluorescence spectrum of TPOR with different molar ratio of CB[7]are measured.The optimum molar ratio of CB[7]and TPOR was determined by isothermal titration test and electron microscope observation.The diameter of TPOR and TPOR/?CB[7]?₄ were determined by dynamic light scattering.The singlet oxygen in the drug solution was tested by SOSG?Singlet Oxygen Sensor Green?.The viability of SH-SY5Y cells was examined by MTT assay.The location of TPOR and TPOR/?CB[7]?₄ in cells were observed by means of a laser confocal microscope.The change of the intracellular ROS?Reactive Oxygen Species?and the light conditions were detected by means of a fluorescence probe?DCFH-DA?.Furthermore,the apoptosis of SH-SY5Y cells were investigated by Annexin V-FITC/PI.Results:The structure of TPOR was characterized by ¹H HMR.Isothermal titration calorimetry experiment and electron microscopy observation indicating the best ratio of CB[7]/TPOR is 4:1,and which further confirmed by the Ultraviolet-visible absorption spectra and the fluorescence emission.The dynamic laser scattering spectra showed that the TPOR/?CB[7]?₄ solution exhibits a unimodal distribution.After irradiation with a 525 nm laser,the group of TPOR/?CB[7]?₄ generated approximately 3 times more singlet oxygen than did the uncomplexed TPOR.It was observed that the TPOR and TPOR/?CB[7]?₄ as photosensitizers mainly localized in the cytoplasm,and the group of TPOR/?CB[7]?₄ had more red fluorescence.The survival rates of the cells irradiation at 525 nm and fluence 0²50 mW/cm² for 0⁴min,showed no significant cell toxicity compared to the control group.The survival rates of the cells incubated with TPOR or TPOR/?CB[7]?₄ at a series of concentrations up to 12.5?mol/L for 24 h in the dark,showed no significant cell toxicity compared to the control group.Upon irradiation at 525 nm and fluence?45.8 mW/cm²,95.5mW/cm²?for 0² min,the cell viability treated with TPOR/?CB[7]?₄ rapidly decreased than the group of TPOR?P<0.05?.There also observed strong ROS-generation ability of TPOR/?CB[7]?₄ under light irradiation?P<0.05?.The apoptotic rate of TPOR/?CB[7]?₄-PDT was significantly increased after 6 hours of photodynamic therapy?P<0.01?.Conclusion:In this work,the use of CB[7]hosts efficiently inhibited the aggregation-induced self-quenching of porphyrin cationic guests in aqueous medium.As a result,highly enhanced photosensitization was achieved.We expect that the present study will extend applications of the supramolecular photosensitizers in PDT systems.