Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Université Paris-Sud, F-91405 Orsay Cedex.
J Phys Chem A. 2010 Mar 11;114(9):3334-9. doi: 10.1021/jp910387a.
Photodynamic inactivation (PDI) is currently receiving interest for its potential as an antimicrobial treatment. Although photosensitizing agents and light have been used for medical purposes for a very long time, only a little information is available about the mechanism of PDI for bacteria. Pseudomonas aeruginosa is a gram negative bacteria involved in chronic infections in cystic fibrosis patients and also one of the commonest agents of hospital acquired infections. In the present study the sensitivity of Pseudomonas aeruginosa to the phototoxic effects of the mono(acridyl)bis(arginyl)porphyrin (MABAP) has been investigated as well as the photophysical and photochemical properties of this cationic porphyrin complexed to poly(dG-dC) to investigate the mechanisms that lead to bacteria inactivation. Both picosecond time-resolved fluorescence and femtosecond to nanosecond transient absorption measurements give evidence that while MABAP can react through its triplet state and/or an ultrafast electron transfer with guanine, its intercalation between GC base pairs is not the main target of MABAP photoactivity. The analysis of both fluorescence emission and excitation spectra reveals the occurrence of an energy transfer through the DNA double helix between the acridine and porphyrin chromophores of MABAP, as previously observed for the stacked free molecule in solution. This efficient process may lead to the excitation of twice more porphyrin chromophores in MABAP by comparison to other cationic porphyrins.
光动力灭活（PDI）目前因其作为一种抗菌处理方法的潜力而受到关注。尽管光敏剂和光已经用于医疗目的很长时间了，但关于 PDI 对细菌的作用机制的信息却很少。铜绿假单胞菌是一种革兰氏阴性细菌，与囊性纤维化患者的慢性感染有关，也是医院获得性感染最常见的病原体之一。在本研究中，研究了单（吖啶基）双（精氨酸基）卟啉（MABAP）对铜绿假单胞菌的光毒性作用的敏感性，以及该阳离子卟啉与[poly(dG-dC)]（2）配位的光物理和光化学性质，以研究导致细菌失活的机制。皮秒时间分辨荧光和飞秒到纳秒瞬态吸收测量都表明，虽然 MABAP 可以通过其三重态和/或超快电子转移与鸟嘌呤反应，但它在 GC 碱基对之间的插入不是 MABAP 光活性的主要靶标。荧光发射和激发光谱的分析揭示了 MABAP 中吖啶和卟啉发色团之间通过 DNA 双螺旋发生能量转移，这与溶液中堆叠自由分子中观察到的情况相同。与其他阳离子卟啉相比，这种有效的过程可能导致 MABAP 中卟啉发色团的激发增加两倍。
