Herenyi Levente, Veres Dániel, Békási Sándor, Voszka István, Módos Károly, Csík Gabriella, Kaposi András D, Fidy Judit
Department of Biophysics and Radiation Biology, Semmelweis University, P. O. Box 263, H-1444 Budapest, Hungary.
J Phys Chem B. 2009 May 28;113(21):7716-24. doi: 10.1021/jp9022184.
Binding of photosensitizers to target cells is a crucial step during the photodynamic effect. Sensitizer distribution is a good indication of whether the chemical is a good candidate for perturbing cell membrane integrity. Hence, the photophysical properties of porphyrinoid sensitizers in microheterogeneous systems such as liposomes are of outstanding interest. Here we present a site-selective fluorescence study of liposome systems. Monocomponent, small unilamellar vesicles formed of different phosphatidylcholines with incorporated mesoporphyrin were investigated. The size distribution of liposomes was measured by dynamic light scattering after each step of the experiment. On the basis of fluorescence line narrowing spectra of mesoporphyrin, the inhomogeneous distribution function was determined in order to characterize the photosensitizer location. The dual character of the functions revealed two different locations. Decomposition of the inhomogeneous distribution functions into Gaussians and the analysis of the fit results suggest that one of the locations for mesoporphyrin is between the two lipid layers, and the other one is between the hydrocarbon chains of the lipid molecules.
光敏剂与靶细胞的结合是光动力效应过程中的关键步骤。敏化剂分布是判断一种化学物质是否是破坏细胞膜完整性的良好候选物的一个很好指标。因此，卟啉类敏化剂在脂质体等微非均相体系中的光物理性质备受关注。在此，我们展示了对脂质体系统的位点选择性荧光研究。研究了由不同磷脂酰胆碱形成并掺入中卟啉的单组分小单层囊泡。在实验的每个步骤之后，通过动态光散射测量脂质体的大小分布。基于中卟啉的荧光线窄化光谱，确定了非均匀分布函数以表征光敏剂的位置。这些函数的双重特性揭示了两个不同的位置。将非均匀分布函数分解为高斯函数并对拟合结果进行分析表明，中卟啉的一个位置在两个脂质层之间，另一个位置在脂质分子的烃链之间。
