Supramolecular Assemblies with Near-Infrared Emission Mediated in Two Stages by Cucurbituril and Amphiphilic Calixarene for Lysosome-Targeted Cell Imaging.

A two-stage mediated near-infrared (NIR) emissive supramolecular assembly for lysosome-targeted cell imaging is presented. 4,4'-Anthracene-9,10-diylbis(ethene-2,1-diyl))bis(1-ethylpyridin-1-ium) bromide (ENDT) was synthesized as an organic dye with weak fluorescence emission at 625 nm. When ENDT complexes with cucurbit[8]uril (CB[8]), this binary supramolecular complex assembles into nanorods with a near-infrared fluorescence emission (655 nm) and fluorescence enhancement as the first stage. Such supramolecular complexes interact with lower-rim dodecyl-modified sulfonatocalix[4]arene (SC4AD) to form nanoparticles for further fluorescence enhancement as the second stage. Furthermore, based on a co-staining experiment with LysoTracker Blue, such nanoparticles can be applied in NIR lysosome-targeted cell imaging.