Study On Optical Properties Of A Novel Chlorin Photosensitizer

Photodynamic therapy(PDT)utilizes the combined action of photosensitizer,light,and molecular oxygen to generate reactive oxygen species(ROS),causing local cell death or tissue necrosis and eventually to treat diseases.Photodynamic reactions require the mediation of photosensitizers,and the performance of photosensitizers has an important influence on the therapeutic effect.It is very important to develop an ideal photosensitizer.The chlorin photosensitizer have characteristics of single component,definite molecular structure,longer maximum absorption wavelength,deep tissue penetration,higher molar extinction coefficient,and high singlet oxygen quantum yield.This study evaluated a novel chlorin photosensitizer-namely YLG-1.The main experimental contents and results of this dissertation include:(1)The absorption spectrum of YLG-1 in different solvents was studied.The results showed that for YLG-1 photosensitizer,there was a strong absorption peak around 400 nm in the ultraviolet band,as well as 500 nm,600 nm,and 650 nm in the visible light band.The peak positions and the corresponding shapes of each spectrum in the solvents are similar.(2)The fluorescence excitation and fluorescence emission spectrum of YLG-1 with the same concentration of different solvents was studied.The results showed that for YLG-1 fluorescence excitation spectrum in different solvents,the peak positions and the corresponding shapes of each spectrum are similar.Compared with the emission peak in the 5%Glucose,the peaks of YLG-1 in DMSO,PBS and 20%FBS showed a red shift of about 10 nm at the peak position in the visible light band.(3)The fluorescence lifetime of YLG-1 in different solvents was compared.The results showed that YLG-1 had the longest fluorescence lifetime of 5.16 ns in 20%FBS and 5.04 ns in DMSO.The fluorescence lifetime values are relatively close to each other.(4)Singlet oxygen detection experiments,the results showed that the singlet oxygen emission signal can be detected using 400nm wavelength light as the excitation light.(5)Photobleaching experiments were carried out under different exposure times for YLG-1 dissolved in the same solvent with different concentrations.Comparing the fluorescence emission spectrum of non-illumination and illumination,it can be seen that the overlap of these spectra is good.The results showed that pure solution did not produce photoproduct under irradiation conditions;the fitting of the photobleaching kinetic curve conformed to the double-exponential decay characteristics.This showed that YLG-1 had a strong photodynamic effect.(6)Skin phototoxicity experiments were carried out using different concentrations,different doses,different incubation times,and different irradiation doses.The results showed that the surface daubing of YLG-1 could not permeate through the skin tissue,so the phototoxicity of the skin was not caused after the irradiation,the hair grew normally and hair follicles were not damaged.(7)Preliminary trials of antitumor efficacy of YLG-1 in wistar rat,showed that YLG-1 photosensitizer may have a certain effect on the treatment of tumors,but the experimental reproducibility is not enough,the above results have yet to be verified.The above experiments systematically analyzed the basic optical properties of YLG-1,showed that YLG-1 had obvious and good photosensitizer characteristics,and had the feasibility for photodynamic therapy.