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Fluorescence Turn-ON Displacement Assays with Cucurbit[7]uril-Thiophenylpyridinium Complexes as Host-Dye Reporter
Mohammad A Alnajjar1, Andreas Hennig1
1Center for Cellular Nanoanalytics (CellNanOs) and Department of Biology and Chemistry, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück, Germany.
Abstract:
The N-methyl-4-thiophenylpyridinium cation (ThioPy) is a high affinity (Kd ca. 5 nM), fast-exchanging fluorescent probe for cucurbit[7]uril (CB7). The CB7/ThioPy complex shows a unique fluorescence turn-ON response upon displacement by an analyte in sensing application. This enabled the development of a real-time fluorescence assay with the MRFA peptide for the protease thermolysin, which is also suitable for the cancer biomarker cathepsin B. Moreover, liposome encapsulation of CB7/ThioPy in large unilamellar vesicles (LUVs) provided mechanistic insight into intravesicular dye displacement reactions.

