Electrostatic attraction-induced aggregation of polymer dots for the facile detection of melamine migration

Many polymer dot (Pdot)-based assays involve complicated modifications for target recognition and detection. In this work, the fluorescence quenching of Pdots based on electrostatic attraction-induced aggregation was proposed for the first time. It was demonstrated that the prepared Pdots were negatively charged and electron-rich (e-Pdots), while protonated melamine was positively charged and electron-withdrawing. Therefore, the melamine was likely to electrostatically attract the e-Pdots, resulting in the aggregation of a melamine–e-Pdot complex. Meanwhile, the electron-transfer from the e-Pdots to the protonated melamine resulted in a remarkable fluorescence quenching. Accordingly, an e-Pdot-based assay was developed for the facile detection of melamine in the range of 0.1–100 nM and the limit of detection was as low as 0.03 nM. Furthermore, this method was applied for monitoring the melamine migration from a resin bowl, and the satisfactory results prove the promising applications of these e-Pdots.