Bünzli Jean-Claude G, Chauvin Anne-Sophie, Vandevyver Caroline D B, Bo Song, Comby Steve
Laboratory of Lanthanide Supramolecular Chemistry, Ecole Polytechnique Fédérale de Lausanne, BCH 1402, CH-1015 Lausanne, Switzerland.
Ann N Y Acad Sci. 2008;1130:97-105. doi: 10.1196/annals.1430.010.
As the need for targeting luminescent biolabels increases, for mapping selected analytes, imaging of cells and organs, and tracking in cellulo processes, lanthanide bimetallic helicates are emerging as versatile bioprobes. The wrapping of three ligand strands around two metallic centers by self-assembly affords robust molecular edifices with tunable chemical and photophysical properties. In addition, heterometallic helical chelates can be assembled leading to bioprobes with inherent chiral properties. In this paper, we review the literature demonstrating that neutral [Ln(2)(L(CX))(3)] (x=1-3) helicates represent a viable alternative to existing chelating agents for bio-analyses, while featuring specific enhanced properties. These bimetallic chelates self-assemble in water, and at physiological pH the 2:3 (Ln:L(CX)) complex is by far the dominant species, conditional stability constants logbeta(23) being in the range 23-30. The metal ions are 9-coordinate and lie in sites with slightly distorted D(3) symmetry. Efficient protection from water interaction by the tightly wrapped ligand strands results in sizeable photophysical properties, with quantum yields up to 24% for Eu(III) and 11% for Tb(III), while the luminescence of several other visible and/or near-infrared emitting Ln(III) ions is also sensitized. Noncytotoxicity for all the helicates is established for several living cell lines including HeLa, HaCat, MCF-7, 5D10, and Jurkat. We present new data pertaining to the live cell imaging ability of [Eu(2)(L(C1))(3)] and compare the three systems with x=1-3 with respect to thermodynamic stability, photophysics, cell-permeation ability, and targeting capability for sensing in cellulo processes. Prospects of derivatization for characterizing specific biological interactions are discussed.
随着对用于映射选定分析物、细胞和器官成像以及细胞内过程追踪的发光生物标记物的需求不断增加，镧系双金属螺旋配合物正成为多功能生物探针。通过自组装将三条配体链缠绕在两个金属中心周围，可提供具有可调化学和光物理性质的坚固分子结构。此外，可以组装异金属螺旋螯合物，从而得到具有固有手性性质的生物探针。在本文中，我们回顾了相关文献，这些文献表明中性[Ln(2)(L(CX))(3)] (x = 1 - 3)螺旋配合物是现有生物分析螯合剂的可行替代品，同时具有特定的增强性质。这些双金属螯合物在水中自组装，在生理pH值下，2:3（Ln:L(CX)）配合物是迄今为止的主要物种，条件稳定常数logbeta(23)在23 - 30范围内。金属离子为九配位，位于具有轻微扭曲D(3)对称性的位点。紧密缠绕的配体链有效地防止了与水的相互作用，从而产生了可观的光物理性质，Eu(III)的量子产率高达24%，Tb(III)的量子产率高达11%，同时其他几种发射可见光和/或近红外光的Ln(III)离子的发光也得到了增强。已确定包括HeLa、HaCat、MCF - 7、5D10和Jurkat在内的几种活细胞系对所有螺旋配合物均无细胞毒性。我们展示了与[Eu(2)(L(C1))(3)]的活细胞成像能力相关的新数据，并比较了x = 1 - 3的三种体系在热力学稳定性、光物理性质、细胞渗透能力和细胞内过程传感靶向能力方面的差异。还讨论了用于表征特定生物相互作用的衍生化前景。
