Korinek Miloslav, Dedic Roman, Svoboda Antonin, Hála Jan
Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Czech Republic.
J Fluoresc. 2004 Jan;14(1):71-4. doi: 10.1023/b:jofl.0000014662.63020.93.
The research in the field of the photodynamic therapy of cancer (PDT) is focused on a development of photosensitizers exhibiting high quantum yield of singlet oxygen production. Direct time-resolved spectroscopic observation of singlet oxygen phosphorescence can provide time constants of its population and depopulation as well as photosensitizer phosphorescence lifetime and relative quantum yields. In our contribution, a study of time and spectral resolved phosphorescence of singlet oxygen photosensitized by meso-tetraphenylporphine in acetone together with the photosensitizer phosphorescence is presented. Time constants of singlet oxygen population and depopulation were determined at wide range of photosensitizer concentrations. The time constant of singlet oxygen generation (0.28 +/- 0.01) micros is slightly shorter then the lifetime of photosensitizer's triplet state (0.32 +/- 0.01) micros. It is caused by lower ability of TPP aggregates to transfer excitation energy to oxygen. The lifetime of singlet oxygen (approximately 50 micros) decreases with increasing photosensitizer concentration. Therefore, the photosensitizer acts also as a quencher of oxygen singlet state, similarly to the effects observed in [A. A. Krasnovsky, P. Cheng, R. E. Blankenship, T. A. Moore, and D. Gust (1993). Photochem. Photobiol. 57, 324-330; H. Küpper, R. Dedic, A. Svoboda, J. Hála, and P. M. H. Kroneck (2002). Biochim. Biophys. Acta Gen. Subj. 1572, 107-113]. Moreover, the increasing concentration of the photosensitizer causes a slight hypsochromic shift of the singlet oxygen luminescence maximum.
癌症光动力疗法（PDT）领域的研究聚焦于开发具有高单线态氧产生量子产率的光敏剂。单线态氧磷光的直接时间分辨光谱观测可以提供其产生和消失的时间常数，以及光敏剂磷光寿命和相对量子产率。在我们的研究中，呈现了对丙酮中由中位四苯基卟啉光敏化产生的单线态氧的时间分辨和光谱分辨磷光以及光敏剂磷光的研究。在较宽的光敏剂浓度范围内测定了单线态氧产生和消失的时间常数。单线态氧生成的时间常数（0.28±0.01）微秒略短于光敏剂三重态的寿命（0.32±0.01）微秒。这是由于TPP聚集体将激发能转移给氧的能力较低所致。单线态氧的寿命（约50微秒）随着光敏剂浓度的增加而降低。因此，光敏剂也起到了单线态氧淬灭剂的作用，这与在[A. A. Krasnovsky, P. Cheng, R. E. Blankenship, T. A. Moore, and D. Gust (1993). Photochem. Photobiol. 57, 324 - 330; H. Küpper, R. Dedic, A. Svoboda, J. Hála, and P. M. H. Kroneck (2002). Biochim. Biophys. Acta Gen. Subj. 1572, 107 - 113]中观察到的效应类似。此外，光敏剂浓度的增加会导致单线态氧发光最大值出现轻微的蓝移。
