The Existence State, Mechanism And Dynamic Reaction Rules Of HMME In Different Solvents As An Amphiphilic Photosensitizer

ObjectiveTo investigate the existence state of amphiphilic photosensitizer HMME in different solvents. Analyse the photobleaching mechanism and dynamic reaction rules of HMME in different solvents, calculate the photobleaching rate constants to provide information for the clinical application of HMME-PDT for Port Wain Stains, and for the study of mathematic model of HMME-PDT for Port Wain Stains.Methods & Results(1) We chose four solvents: PBS (Phosphate Buffered Saline), Dimethyl Sulfoxide (DMSO), Albumin buffer and Cells suspension. And chose concentrations 2, 4, 8, 10, 20, 40, 60, 80, 100umol/L for each group, took hydrophobic photosensitizer HpD as a contrast. We qualitatively analyzed the existence state of HMME by comparing the character of absorption and the fluorescence spectra of HMME in each solvent, and quantificationally analyzed the HMME solutions in which HMME aggregations had formed by calculating the association number, association degree and aggregation constant of HMME. The existence state of HpD in these four solvents was analyzed with the same method. The qualitative analysis results showed that: in each solvent, there was no obvious change in the absorbance spectra of HMME from 2μmol/L to 10μmol/L, the absorbance spectra and the excited fluorescence spectra were overlapped. At concentration from 20μmol/L to 100μmol/L, the absorbance band at 380nm for HMME aggregations appeared in all the absorbance spectra of HMME in PBS, Albumin buffer and Cells suspension, the absorbance spectra and the excited fluorescence spectra were not overlapped. The absorbance band of aggregations began to form at 60μmol/L for HMME, while at 20μmol/L for HpD. Quantificational analysis results showed that in PBS, Albumin buffer and Cells suspension, at concentration from 20 to 100μmol/L differentpercent of HMME molecules aggregated and formed into dimmers. The aggregation constants of HMME in Albumin buffer, PBS, Cells suspension were 1.2×10~3L/moL, 2.3×10~3L/moL, 2.8×10~3L/moL respectively, and were smaller than that of HpD in according solvent(3.4×10~3L/moL, 6.9×10~2L/moL, 5.2×10~3L/moL). The association degrees (the percent of monomers at a certain concentration) at each concentration are smaller than those of HpD.(2) The photobleaching of HMME in PBS, DMSO, Albumin solution and in Cells suspension was measured by the decline of absorbance value of HMME before and after prolonged exposure to laser irradiation (532nm, 80mW/cm~2). By comparing the photobleaching of HMME under different condition—bubbled with oxygen, bubbled with argon, added with singlet oxygen quenchers, added with hydroxyl radical quencher, to analyze the photobleaching mechanism of HMME. The results showed that in PBS, DMSO, Albumin buffer and Cells suspension, HMME was photobleached the fast, the bleaching was obviously inhibited while bubbled with argon or added with singlet oxygen quenchers. In PBS, DMSO the photobleaching of HMME was inhibited by hydroxyl radical quencher, but its inhibition function was smaller than that of singlet oxygen quenchers and argon. In Albumin buffer, the inhibition function of hydroxyl radical quencher for HMME photobleaching was bigger than in PBS and DMSO, but it was smaller than that of singlet oxygen quenchers and argon. In Cells suspension, the inhibition function of hydroxyl radical quencher for HMME photobleaching was was resemble to at of singlet oxygen quenchers, but still smaller than that of argon.(3) According to the exisitance of photooxidizable substrates, we classified the solvents in which HMME dissolved into simple solvents (PBS and DMSO) and complex solvents which contain photooxidizable substrates (albumin solution and cells suspension). Firstly, we analyzed the reaction dynamic rules of HMME based on the reaction dynamic theory and the photochemical reactions of photobleaching: the bleaching followed a first order dynamic process in simple solvents and a second order dynamic process in complex solvents. Secondly, the dynamic data of photobleaching for HMME (HMME concentration at different irradiation time) in different solvents was collected by measuring the absorbance value at different time before and after laser irradiation (532nm, 80mW/cm~2). For each solvent and...