Experimental Study On The Optical Characterization Of Photosensitizers For Photodynamic Therapy

This study was supported in part by the key Science and Technology project of Fujian Provincial Education Bureau under grant JA01014, and in part by the National Natural Science Foundation of China under grant 60178022. The major work in this thesis is devoted to experimental study on the optical characterization of photosensitizers for photodynamic therapy.Firstly, the mechanism of photodynamic therapy and the developmental history and present situations of photosensitizers were presented. In recent years, a number of second-generation photosensitizers have been developed to overcome the shortcomings of first-generation photosensitizers ,which have many preferred advantage in the preliminary clinical application. The investigation of the optical characterization of photosensitizers was the fundamental basic for the development of optical biopsy system.Secondly, the study of the properties of photosensitizers, which mainly including the fluorescence yield, spectral properties, photobleaching properties of photosensitizers were carried out. The optimal excitation and detection wavelength of photosensitizers can be determined according to the fluorescence excitation and emission spectra of photosensitizers respectively. Furthermore, the photobleaching properties of photosensitizers were studied in detail in this chapter,which also should be taken into account in clinical diagnosis and therapy with photosensitizer.Thirdly, experiments have been performed to study spectrum and photobleaching properties of new photosensitizers and the first-generation photosensitizers. Experimenttal results show that the maximum absorption peaks for ZnPcS2P2 appear at 679nm and for BpD-MA at 439nm, however for HpD , PsD-007 and HMME at 400nm. There are fluorescence peaks appear at 630nm or 690 nm in fluorescence emission spectra for five photosensitizers.Experiments about photobleaching properties for HpD, PsD-007 and HMME show the photobleaching time of photosensitizers increased when the concentration of photosensitizers in the solution increased. On the contrary the photobleaching time of photosensitizers decreased when the power of irradiation laser increased. At A =514niru C=3M-g/ml and P=15mW, the photobleaching time of HpD is shortest about 190 seconds, then for PsD-007 is about 205 seconds and for HMME is 240 seconds.