Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany.
Mol Imaging. 2011 Aug;10(4):258-69. doi: 10.2310/7290.2011.00005. Epub 2011 Apr 26.
To assess the suitability of asymmetric cyanine dyes for in vivo fluoro-optical molecular imaging, a comprehensive study on the influence of the number of negatively charged sulfonate groups governing the hydrophilicity of the DY-67x family of asymmetric cyanines was performed. Special attention was devoted to the plasma protein binding capacity and related pharmacokinetic properties. Four members of the DY-67x cyanine family composed of the same main chromophore, but substituted with a sequentially increasing number of sulfonate groups (n = 1-4; DY-675, DY-676, DY-677, DY-678, respectively), were incubated with plasma proteins dissolved in phosphate-buffered saline. Protein binding was assessed by absorption spectroscopy, gel electrophoresis, ultrafiltration, and dialysis. Distribution of dye in organs was studied by intraveneous injection of 62 nmol dye/kg body weight into mice (n = 12; up to 180 minutes postinjection) using whole-body near-infrared fluorescence imaging. Spectroscopic studies, gel electrophoresis, and dialysis demonstrated reduced protein binding with increasing number of sulfonate groups. The bovine serum albumin binding constant of the most hydrophobic dye, DY-675, is 18 times higher than that of the most hydrophilic fluorophore, DY-678. In vivo biodistribution analysis underlined a considerable influence of dye hydrophilicity on biodistribution and excretion pathways, with the more hydrophobic dyes, DY-675 and DY-676, accumulating in the liver, followed by strong fluorescence signals in bile and gut owing to accumulation in feces and comparatively hydrophilic DY-678-COOH accumulating in the bladder. Our results demonstrate the possibility of selectively controlling dye-protein interactions and, thus, biodistribution and excretion pathways via proper choice of the fluorophore's substitution pattern. This underlines the importance of structure-property relationships for fluorescent labels. Moreover, our data could provide the basis for the rationalization of future contrast agent developments.
为了评估不对称菁染料在体内荧光光学分子成像中的适用性，我们对影响 DY-67x 家族不对称菁染料亲水性的磺酸基数目的综合研究进行了研究。特别关注的是血浆蛋白结合能力和相关的药代动力学性质。DY-67x 菁染料家族的四个成员由相同的主要发色团组成，但取代了数量逐渐增加的磺酸基（n = 1-4；分别为 DY-675、DY-676、DY-677、DY-678），与溶解在磷酸盐缓冲盐溶液中的血浆蛋白一起孵育。通过吸收光谱、凝胶电泳、超滤和透析评估蛋白质结合。通过静脉注射 62 nmol 染料/kg 体重（注射后最多 180 分钟）将染料注射到小鼠中，研究了染料在器官中的分布情况（n = 12），并使用全身近红外荧光成像。光谱研究、凝胶电泳和透析表明，随着磺酸基数目的增加，蛋白质结合减少。最疏水染料 DY-675 的牛血清白蛋白结合常数是最亲水荧光团 DY-678 的 18 倍。体内生物分布分析强调了染料亲水性对生物分布和排泄途径的显著影响，疏水性染料 DY-675 和 DY-676 积聚在肝脏中，随后由于积聚在粪便中，胆汁和肠道中出现强烈的荧光信号，而相对亲水的 DY-678-COOH 积聚在膀胱中。我们的结果表明，通过适当选择荧光团的取代模式，有可能选择性地控制染料-蛋白质相互作用以及生物分布和排泄途径。这强调了结构-性质关系对于荧光标记物的重要性。此外，我们的数据可以为未来对比剂开发的合理化提供依据。
