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.