Introduction

Although photophysical properties of Radachlorin photosensitizer (PS) were extensively studied in solutions and cells, no data is available on variations of its characteristics upon binding to serum albumins, which are major transporters in blood and nutrients in cell culture media.

Objectives

The primary objective of this study was to analyze changes in photophysical properties of Radachlorin molecules upon their binding to human and bovine serum albumins at different microenvironment properties.

Methods

Experiments were performed using time-resolved fluorescence spectroscopy and fluorescence recovery after photobleaching. Variations in fluorescence spectra and lifetime, fluorescence anisotropy, rotational and translational diffusion of PS molecules upon binding to albumins were studied in normal, basic and acidic conditions and at different concentrations of albumin and PS molecules.

Results

Radachlorin molecules effectively bind to both types of serum albumins, which causes changes in photophysical properties of the PS. A minor red shift of the fluorescence spectrum, an increase in fluorescence lifetime and anisotropy and substantial decrease of translational and rotational mobility of PS molecules were observed upon their binding to albumins. The analysis of rotational diffusion time provided robust evaluation of the bound fraction of PS molecules. Both the highly acidic microenvironment and increase in alcohol concentration above 40% resulted in detachment of PS molecules from albumins. Photophysical properties of Radachlorin in complexes with BSA and HSA were found to be slightly different.

Conclusions

Binding of Radachlorin photosensitizer to either BSA or HSA affects significantly its photophysical properties, which may also vary with microenvironment acidity and alcohol concentration.

中文翻译：

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拉达氯林光敏剂与血清白蛋白结合后的光物理、旋转和平移特性

介绍

尽管拉达氯林光敏剂 (PS) 的光物理特性在溶液和细胞中得到了广泛研究，但没有关于其与血清白蛋白结合后特性变化的数据，血清白蛋白是血液和细胞培养基中营养物质的主要转运蛋白。

目标

本研究的主要目的是分析拉达氯林分子在不同微环境特性下与人和牛血清白蛋白结合后光物理特性的变化。

方法

使用时间分辨荧光光谱和光漂白后的荧光恢复进行实验。在正常、碱性和酸性条件下以及不同浓度的白蛋白和PS分子下，研究了与白蛋白结合后PS分子的荧光光谱和寿命、荧光各向异性、旋转和平移扩散的变化。

结果

拉达二氢氯酸分子有效地与两种类型的血清白蛋白结合，从而导致 PS 的光物理特性发生变化。在与白蛋白结合后，观察到荧光光谱的轻微红移、荧光寿命和各向异性的增加以及PS分子的平移和旋转迁移率的显着降低。旋转扩散时间的分析为 PS 分子的结合分数提供了可靠的评估。高酸性微环境和酒精浓度超过 40% 都会导致 PS 分子与白蛋白分离。发现 Radalorin 与 BSA 和 HSA 复合物的光物理性质略有不同。

结论

Radalorin 光敏剂与 BSA 或 HSA 的结合会显着影响其光物理性质，这也可能随微环境酸度和酒精浓度而变化。