Baier Jürgen, Maier Max, Engl Roland, Landthaler Michael, Bäumler Wolfgang
Department of Dermatology, University of Regensburg, Germany, and Institute of Experimental and Applied Physics, University of Regensburg, Germany.
J Phys Chem B. 2005 Feb 24;109(7):3041-6. doi: 10.1021/jp0455531.
Singlet oxygen was generated by energy transfer from the photoexcited sensitizer, Photofrin or 9-acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene (ATMPn), to molecular oxygen. Singlet oxygen was detected time-resolved by its luminescence at 1270 nm in an environment of increasing complexity, water (H2O), pure phosphatidylcholine, phosphatidylcholine in water (lipid suspensions), and aqueous suspensions of living cells. In the case of the lipid suspensions, the sensitizers accumulated in the lipids, whereas the localizations in the cells are the membranes containing phosphatidylcholine. By use of Photofrin, the measured luminescence decay times of singlet oxygen were 3.5 +/- 0.5 micros in water, 14 +/- 2 micros in lipid, 9 +/- 2 micros in aqueous suspensions of lipid droplets, and 10 +/- 3 micros in aqueous suspensions of human colonic cancer cells (HT29). The decay time in cell suspensions was much longer than in water and was comparable to the value in suspensions of phosphatidylcholine. That luminescence signal might be attributed to singlet oxygen decaying in the lipid areas of cellular membranes. The measured luminescence decay times of singlet oxygen excited by ATMPn in pure lipid and lipid suspensions were the same within the experimental error as for Photofrin. In contrast to experiments with Photofrin, the decay time in aqueous suspension of HT29 cells was 6 +/- 2 micros when using ATMPn.
单线态氧是通过光激发敏化剂（血卟啉或9-乙酰氧基-2,7,12,17-四（β-甲氧基乙基）-卟吩（ATMPn））向分子氧的能量转移而产生的。在水（H₂O）、纯磷脂酰胆碱、水中的磷脂酰胆碱（脂质悬浮液）和活细胞的水悬浮液等日益复杂的环境中，通过其在1270 nm处的发光对单线态氧进行时间分辨检测。在脂质悬浮液的情况下，敏化剂积聚在脂质中，而在细胞中的定位是含有磷脂酰胆碱的膜。使用血卟啉时，测得的单线态氧在水中的发光衰减时间为3.5±0.5微秒，在脂质中为14±2微秒，在脂质滴的水悬浮液中为9±2微秒，在人结肠癌细胞（HT29）的水悬浮液中为10±3微秒。细胞悬浮液中的衰减时间比在水中长得多，与磷脂酰胆碱悬浮液中的值相当。该发光信号可能归因于细胞膜脂质区域中衰减的单线态氧。在实验误差范围内，ATMPn激发的单线态氧在纯脂质和脂质悬浮液中的发光衰减时间与血卟啉的相同。与血卟啉的实验不同，使用ATMPn时，HT29细胞水悬浮液中的衰减时间为6±2微秒。
