Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-L-α-phosphatidylcholine vesicles
Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-L-α-phosphatidylcholine vesicles
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DOI：
10.1039/b513219c
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发表时间：
2006-01-01
影响因子：
3.1
通讯作者：
Hoebeke, M
中科院分区：
文献类型：
--
作者：
Delanaye, L;Bahri, MA;Hoebeke, M
研究了第二代光敏剂焦脱镁叶绿酸a甲酯(PPME)在不同溶剂中的聚集过程。吸收光谱和荧光光谱表明，该光敏剂在乙醇和双肉豆蔻-L-α-磷脂酰胆碱脂质体中均以单体形式存在，而在磷酸盐缓冲液中有较强的聚集。用电子自旋共振结合自旋捕捉技术和吸收光谱定量测定了PPME在这些溶剂中产生的活性氧物种。在磷酸盐缓冲溶液中，电子自旋共振和吸收测量都得出结论：在磷酸盐缓冲溶液中，没有检测到单线态氧的产生，而羟基自由基的产生很弱。在脂质体和乙醇中，单线态氧和羟基自由基产生量显著增加，测得乙醇中单线态氧量子产率为0.2，脂质体中为0.13。并对羟基自由基的产生来源进行了探讨。在氧气存在下，PPME三重态失活形成单线态氧。事实上，PPME的三重态形成量子产率在乙醇中约为0.23，在脂质体中约为0.15(太小而无法在PBS中测量)。
The aggregation process of pyropheophorbide-a methyl ester ( PPME), a second-generation photosensitizer, was investigated in various solvents. Absorption and fluorescence spectra showed that the photosensitizer was under a monomeric form in ethanol as well as in dimyristoyl-L-alpha-phosphatidylcholine liposomes while it was strongly aggregated in phosphate buffer. A quantitative determination of reactive oxygen species production by PPME in these solvents has been undertaken by electron spin resonance associated with spin trapping technique and absorption spectroscopy. In phosphate buffer, both electron spin resonance and absorption measurements led to the conclusion that singlet oxygen production was not detectable while hydroxyl radical production was very weak. In liposomes and ethanol, singlet oxygen and hydroxyl radical production increased highly; the singlet oxygen quantum yield was determined to be 0.2 in ethanol and 0.13 in liposomes. The hydroxyl radical production origin was also investigated. Singlet oxygen was formed from PPME triplet state deactivation in the presence of oxygen. Indeed, the triplet state formation quantum yield of PPME was found to be about 0.23 in ethanol, 0.15 in liposomes ( too small to be measured in PBS).