Host-Guest Interaction of Hoechst 34580 and Cucurbit[7]uril

• Published in: Chemphyschem Vol. 12; no. 16; pp. 2933 - 2940
• Main Authors: Lei , Wanhua, Zhou, Qianxiong, Jiang , Guoyu, Hou, Yuanjun, Zhang, Baowen, Cheng, Xuexin, Wang, Xuesong
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 18.11.2011; WILEY‐VCH Verlag; Wiley
• Subjects: Atomic and molecular physics; Benzimidazoles - chemistry; Binding Sites; Bridged-Ring Compounds - chemistry; Cell Line, Tumor; Cell Nucleus - chemistry; Cell Nucleus - ultrastructure; Circular Dichroism; cucurbiturils; DNA - chemistry; Drug Interactions; dyes/pigments; Exact sciences and technology; fluorescence; Fluorescence and phosphorescence spectra; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); fluorescence imaging; Fluorescent Dyes - chemistry; host-guest systems; Humans; Imidazoles - chemistry; Magnetic Resonance Spectroscopy; Microscopy, Confocal - methods; Microscopy, Fluorescence - methods; Models, Molecular; Molecular properties and interactions with photons; Molecular Structure; Physics; Solutions; Spectrometry, Fluorescence - methods; Thermodynamics; Time-Lapse Imaging; Phosphates; Fluorescence spectrum; dyes/pigments; Visualization; host-guest systems; Organic dye; cucurbiturils; fluorescence imaging; Fluorescence; Imagery; Intermolecular interaction; Aqueous solutions; Inclusion compounds; Modelling; NMR spectra; Absorption spectra; Cell nuclei
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201100495

To track nuclear dynamic processes by fluorescence imaging, nuclear stains should be highly fluorescent, resistant to photobleaching, and inert to nuclear processes. The nuclear stains of the Hoechst family, such as Hoechst 34580, show bright fluorescence only on groove binding to DNA, and therefore may interfere with visualization of nuclear dynamic processes induced by other stimuli. We study host–guest interactions between Hoechst 34580 and Cucurbit[7]uril (CB7) in aqueous solutions. The formation of CB7–Hoechst 34580 inclusion complexes with stoichiometry of 2:1 in water and 1:1 in phosphate‐buffered saline (PBS) solution (pH 7.0) is confirmed by 1H NMR, absorption spectra, fluorescence spectra, MALDI‐TOF MS, and molecular modeling. Compared to Hoechst 34580, the inclusion complex exhibits redshifted absorption, intensified fluorescence, improved photostability, weakened DNA binding affinity, comparable ability to penetrate cell nuclei, and better nuclear‐staining capability, and thus a new avenue for the application of cucurbituril in fluorescence imaging is opened. Bright is right: The nuclear stain Hoechst 34580 shows bright fluorescence only on groove binding to DNA (picture a), and therefore may interfere with the visualization of nuclear dynamic processes. On inclusion into the cavity of cucurbit[7]uril (CB7), Hoechst 34580 exhibits redshifted absorption, intensified fluorescence, improved photostability, weakened DNA binding affinity, comparable cell‐nucleus penetration ability, and better nuclear staining capability (picture b).