| Photodynamic therapy emerged in the 20 th century.It is a new treatment method for the treatment of diseases such as cancer using the photodynamic effect,and has broad application prospects.However,photodynamic therapy has a problem of unstable efficacy in clinical use.This is due to the limitation of the detection technology.As a result,various parameters in the treatment process cannot be accurately measured,which affects the therapeutic effect.Oxygen is a very important factor in the process of photodynamic therapy,but there is currently no effective means for the measurement of oxygen content in tissues.Phosphorescent oxygen probe method is one of the most studied oxygen measurement methods.The porphyrin doped with gadolinium ions is a kind of multifunctional theranostic agent applied to photodynamic therapy,which has excellent room temperature phosphorescence emission and also has a certain photosensitivity.However,its phosphorescence quantum yield is slightly lower than that of conventional platinum-based metalloporphyrins.Therefore,it is necessary to find ways to increase the phosphorescence quantum yield thereof.In this paper,the optical properties,energy level structural,phosphorescence emission mechanism,sensing ability of oxygen,photosensitivity,and phosphorescence enhancement pathway are studied in gadolinium coordinated hematoporphyrin monomethyl ether(Gd-HMME).A variety of lanthanide metalloporphyrins were synthesized,and their optical properties and the energy level structural properties were studied.In our experiment,the HMME doped with neodymium(Nd),gadolinium(Gd),dysprosium(Dy),erbium(Er)and thulium(Tm)ions were synthesized by the hot solvent method and these metalloporphyrins were characterized by absorption spectra.It was found that the emission spectrum of Gd-HMME had a large red shift compared with HMME,and the luminescence between the wavelength of 675 nm and 850 nm was determined to be phosphorescence by life analysis.Take Nd-HMME as an example,four peaks were found in the Q band of the absorption spectrum which was different from the accepted knowledge(two Q bands)after improving the measurement signal-to-noise ratio of the absorption spectrum.According to the absorption spectrum and emission spectrum,the transition process and the energy level structure diagram of Nd-HMME were given again.The oxygen sensing capability and photosensitivity of Gd-HMME were studied.First,the mechanism of Gd-HMME emitting phosphorescence at room temperature was specifically described.Secondly,it was found that the phosphorescence of Gd-HMME was easily quenched by the oxygen around it and its intensity and lifetime were very sensitive to the change of oxygen.In the experiment,the Stern-Volmer curves of the phosphorescence intensity and lifetime quenched by oxygen were given,with Ksv of 3.79 m M-1 and 3.35 m M-1,respectively.In addition,Gd-HMME was found to have good photosensitivity,and its singlet oxygen quantum yield was measured as 0.38,which can be used as a photosensitizer for photodynamic therapy.The phosphorescence enhancement pathway of Gd-HMME was studied.It was found that the addition of free Gd3+ in the methanol solution of Gd-HMME can greatly increase the phosphorescence emission,and there was a linear relationship between the intensity and the Gd3+ concentration.According to the measurement of absorption spectrum,excitation spectrum,and time-resolved spectrum,the specific mechanism of Gd3+ enhancing phosphorescence emission of Gd-HMME solution was given in combination with the phosphorescence quantum yield formula.Finally,the effects of some other rare earth ions Nd3+,Er3+ and Tm3+ on the phosphorescence emission of GdHMME solution were studied. |
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