Fluorescent Chemosensor for Pyrophosphate <i>via</i> Aggregation-Induced Emission and Principal Component Analysis

The fluorescent chemosensor TPE-NH3, a derivative of tetraphenylethylene (TPE), substituted with four cationic ammonium groups, was developed for the selective detection of pyrophosphate (PPi) anion. With inherent aggregation-induced emission (AIE) characteristics, TPE-NH3 displays strong fluorescence enhancement accompanied by a blue shift upon interacting with PPi. The probe exhibits good selectivity toward PPi over ten other anions that were tested. The interactions between TPE-NH3 and PPi were investigated using Job plot analysis and molecular dynamics simulations. Dynamic light scattering measurements demonstrated a 4.5-fold increase in particle size of the aggregates after the addition of PPi. The morphology of these aggregates has been investigated using transmission electron microscopy and confocal fluorescence lifetime imaging microscopy analyses. Principal component analysis (PCA) was applied to quantify the PPi concentration in unknown samples, giving good accuracy and precision with a relatively low limit of detection (77 nM) and respectable error margins (0.06–8.96%). This combined AIE-based sensing and PCA approach provides a robust, sensitive method for selective PPi detection with significant potential for biomedical and environmental applications.