Pyrophosphate-triggered intermolecular cross-linking of tetraphenylethylene molecules for multianalyte detection

Here we present a fluorogenic multianalyte biosensor based on self-assembled tetraphenylethene (TPE) molecules by modification with diethylenetriamine (TPDA). The TPDA probe could specifically react with pyrophosphate (PPi) by hydrogen linkage. Simulation analysis results indicated that the coupling will lead to intermolecular cross-linking of TPDA molecules and turn on aggregated-induced emission at 470 nm. When alkaline phosphatase (ALP) was introduced, PPi was hydrolyzed and fluorescence emission was turned off. The proposed system allows sensitive detection for ALP activity (LOD = 0.09 mU mL −1 ) and PPi (LOD = 66.7 nM). For ALP assay, this is the first example using PPi to switch AIE phenomenon, which offers better pH selection (pH 7.4) than conventional methods (pH 8.0–9.6). For PPi analysis, this method does not require metal ions, indicating better stability with little interference. We further applied the TPDA-PPi complex as a new substrate for ALP in an immunoassay and proved that the substrate is more sensitive (LOD = 0.8 ng mL −1 ) than traditional one (LOD = 4.0 ng mL −1 ), which means that the complex is greatly potential in ultrasensitive immunoassay for biomedical diagnosis.