Here we report ultrastable synthetic binding pairs between cucurbit[7]uril (CB[7]) and adamantyl- (AdA) or ferrocenyl-ammonium (FcA) as a supramolecular latching system for protein imaging, overcoming the limitations of protein-based binding pairs. Cyanine 3-conjugated CB[7] (Cy3-CB[7]) can visualize AdA- or FcA-labeled proteins to provide clear fluorescence images for accurate and precise analysis of proteins. Furthermore, controllability of the system is demonstrated by treating with a stronger competitor guest. At low temperature, this allows us to selectively detach Cy3-CB[7] from guest-labeled proteins on the cell surface, while leaving Cy3-CB[7] latched to the cytosolic proteins for spatially conditional visualization of target proteins. This work represents a non-protein-based bioimaging tool which has inherent advantages over the widely used protein-based techniques, thereby demonstrating the great potential of this synthetic system.

The host-guest complexes between commercially available fluorescence dyes and cucurbit[n]urils (CB[n], n = 6, 7 and 8) were exploited as multiple sensor elements to provide arrays for sensing biogenic amines using principal component analysis (PCA). Since the sensor elements responds differently to each amine, the array generates distinct patterns of fluorescence changes for each amine. We analyzed these results using PCA to allow precise discrimination of individual biogenic amines. This result demonstrated the great potential of these host-guest complexes as useful sensor elements for biogenic molecules, which may be useful to develop a diagnostic tool for diseases including cancers.

A variety of aliphatic and aromatic ketoaldehydes were reduced to the corresponding ketoalcohols with a mixture of sodium borohydride (1.2 equivalents) and sodium carbonate (sixfold molar excess) in water. Reactions were performed at room temperatures over (typically) 2 h, and yields of isolated products generally ranged from 70% to 85%. A bis-carbonate-borane complex, [(BH₃)₂CO₂]²⁻ 2Na⁺, possibly formed from the reagent mixture, is likely the active reductant. The moderated reactivity of this acylborane species would explain the chemoselectivity observed in the reactions. The readily available reagents and the mild aqueous conditions make for ease of operation and environmental compatibility, and make a useful addition to available methodology. GRAPHICAL ABSTRACT