Fibrous strips decorated with cleavable aggregation-induced emission probes for visual detection of Hg2+

The widespread contamination and high poisonousness have created significant concerns and thus demands for facile, rapid and selective monitoring of trace Hg2+. Inspired from the unique aggregation-induced emission (ME) feature, in the current study, novel tetraphenylethylene (TPE) derivatives are prepared containing sulfonic groups for water solubility modulation and carboxyl dithioacetals for Hg2+ sensing. The TPE derivatives are grafted on electrospun fiber as test papers to initiate the AIE activities, while the Hg2+-specific cleavage of dithioacetal groups leads to the release of TPE derivatives and fluorescence turn-off. The decrease in the fluorescence intensities of fibrous mats could be fitted with Hg2+ levels for quantitative analysis, and the fibrous mats turn from green to bluish-green and then to blue in the presence of different Hg2+ levels. The limit of detection (LOD) reaches as low as 20 nM Hg2+, satisfying the threshold detection in drinking water, and the Hg2+ sensing indicates negligible interference from other metal ions and pH variations. The detected Hg2+ levels in lake water are consistent with the added amount with a recovery rate of over 98 %. It demonstrates a feasible strategy to integrate Hg2+-cleavable ME probes on fibrous strips for real-time, highly specific and naked-eye detection of trace Hg2+.