Hu Changming, Grimm Laura, Prabodh Amrutha, Baksi Ananya, Siennicka Alicja, Levkin Pavel A, Kappes Manfred M, Biedermann Frank
Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
Institute of Physical Chemistry (IPC), Karlsruhe Institute of Technology (KIT) Fritz-Haber-Weg 6 76131 Karlsruhe Germany.
Chem Sci. 2020 Sep 22;11(41):11142-11153. doi: 10.1039/d0sc03079a.
Non-covalent chemosensing ensembles of cucurbit[]urils (CB) have been widely used in proof-of-concept sensing applications, but they are prone to disintegrate in saline media, biological fluids. We show here that covalent cucurbit[7]uril-indicator dye conjugates are buffer- (10× PBS buffer) and saline-stable (up to 1.4 M NaCl) and allow for selective sensing of Parkinson's drug amantadine in human urine and saliva, where the analogous non-covalent CB7⊃dye complex is dysfunctional. The in-depth analysis of the covalent host-dye conjugates in the gas-phase, and deionized saline aqueous media revealed interesting structural, thermodynamic and kinetic effects that are of general interest for the design of CB-based supramolecular chemosensors and systems. This work also introduces a novel high-affinity indicator dye for CB7 through which fundamental limitations of indicator displacement assays (IDA) were exposed, namely an impractical slow equilibration time. Unlike non-covalent CB⊃dye reporter pairs, the conjugate chemosensors can also operate through a S2-type guest-dye exchange mechanism, which shortens assay times and opens new avenues for tailoring analyte-selectivity.
葫芦[n]脲（CB）的非共价化学传感组合已广泛用于概念验证传感应用中，但它们在盐溶液介质、生物流体中容易分解。我们在此表明，共价葫芦[7]脲 - 指示剂染料共轭物在缓冲液（10×PBS缓冲液）和盐溶液（高达1.4 M NaCl）中稳定，并且能够在人尿液和唾液中选择性地检测帕金森病药物金刚烷胺，而类似的非共价CB7⊃染料复合物则无法正常工作。对共价主体 - 染料共轭物在气相、去离子盐水溶液介质中的深入分析揭示了有趣的结构、热力学和动力学效应，这些效应对于基于CB的超分子化学传感器和系统的设计具有普遍意义。这项工作还引入了一种用于CB7的新型高亲和力指示剂染料，通过它暴露了指示剂置换分析（IDA）的基本局限性，即平衡时间过长不切实际。与非共价CB⊃染料报告对不同，共轭化学传感器还可以通过S2型客体 - 染料交换机制运行，这缩短了分析时间并为定制分析物选择性开辟了新途径。
