A water-soluble AIE-gen for organic-solvent-free detection and wash-free imaging of Al ions and subsequent sensing of F ions and DNA tracking

A water-soluble aggregation-induced emission (AIE)-active probe ( TPE-diBuS ) showed selective turn-on fluorescence response and wash-free non-invasive cellular imaging towards Al 3+ ions, based on ionic interactions of Al 3+ ions with diagonally located sulfonate groups of the tetraphenylethylene derivative ( TPE-diBuS ) under organic-solvent-free conditions. The high selectivity of the probe towards Al 3+ resulted from the strong affinity of sulfonate groups with Al 3+ , which was confirmed by discerning Al 3+ over a range of metal ions in a complex mixture. Density functional theory (DFT) studies also confirmed the highest stability for the TPE-diBuS-Al ensemble over other probe-metal complexes in a model study. The limit of detection (LOD) of the probe was determined as 5.0 × 10 −8 M for Al 3+ . Moreover, taking advantage of its high water solubility and good biocompatibility, wash-free imaging of Al 3+ ions was successfully conducted in live human kidney (HK) cells and bright blue fluorescence from intercellular regions of Al 3+ -contaminated cells was observed. The stronger affinity of fluoride ions towards Al 3+ was utilized for subsequent detection of F − ions via a turn-off fluorescence response as the TPE-diBuS-Al ensemble disintegrates into water-soluble non-emissive probe molecules, and the detection limit of F − ions was found to be 6.0 × 10 −7 M. Furthermore, in a demonstration study, it was shown that the TPE-diBuS-Al ensemble could subsequently facilitate tracking of DNA in solution by interaction with calf thymus DNA (ctDNA). Simple synthesis, water solubility, high selectivity and low LOD are some of the key merits of the current probe over existing probes for the detection and quantitation of Al 3+ ions in water, as well as in biological systems. A water-soluble TPE-based AIEgen ( TPE-diBuS ) was developed for organic-solvent-free detection of Al 3+ ions and its wash-free cell imaging. The TPE-diBuS-Al ensemble was used for the detection of F − ions and DNA tracking.