pH 对亚甲蓝瞬态状态和动力学及细菌光灭活的影响。

Effect of pH on methylene blue transient states and kinetics and bacteria photoinactivation.

机构信息

Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics, Shanghai Jiao Tong University, Shanghai, 200240, China.

出版信息

J Phys Chem A. 2011 Apr 7;115(13):2702-7. doi: 10.1021/jp110215g. Epub 2011 Mar 10.

DOI:10.1021/jp110215g

PMID:21391692

Abstract

We have measured directly by time-resolved spectroscopy the transient spectra and kinetics of the methylene blue (MB) excited singlet and triplet state as a function of pH from a few picoseconds to several microseconds. The data show that the acidic triplet state (3)MBH(2+) is the protonated analogue of the basic (3)MB(+). It is also shown that the singlet oxygen formation quantum yield is much higher in basic than in acidic media. The transient spectra and their kinetics suggest that because pH exerts a large influence in singlet oxygen and radical formation, it may also be important in bacteria inactivation. Therefore, we performed experiments, which showed that the rate of gram-positive and gram-negative bacteria inactivation at pH 9 is 3-25 times higher than the rate at pH 5.

摘要

我们已经通过时间分辨光谱法直接测量了亚甲蓝（MB）激发单线态和三线态的瞬态光谱和动力学，其范围从几皮秒到几微秒，pH 值也在这一范围内。数据表明，酸性三线态（3）MBH（2+）是碱性（3）MB（+）的质子化类似物。研究还表明，在碱性介质中，单线态氧的形成量子产率远高于酸性介质。瞬态光谱及其动力学表明，由于 pH 值对单线态氧和自由基的形成有很大的影响，它在细菌失活中也可能很重要。因此，我们进行了实验，结果表明，在 pH 值为 9 时，革兰氏阳性菌和革兰氏阴性菌的失活速率比在 pH 值为 5 时高 3-25 倍。