Quantum dots encoded white-emitting polymeric superparticles for simultaneous detection of multiple heavy metal ions

Simultaneous detection of multiple heavy metal ions (HMI) is of great importance for the environmental monitoring, and the analytical tools based on multiband emissive fluorescent probes have been regarded as one of the most promising candidate for multiple HMI detection. Herein, the rod-coil amphiphilic block copolymer (BCP) with intrinsic blue fluorescence emission has been synthesized and subsequently employed to encapsulate two types of hydrophobic quantum dots (QD) with green and red fluorescence emission via the three dimensionally confined emulsion self-assembly, leading to the generation of white-emitting superparticles showing good colloidal stability and stable aqueous phase fluorescence. Furthermore, it was found that the fluorescence emission intensity of obtained superparticles can be selectively quenched by Ag⁺, Hg²⁺, Cu²⁺ and Fe³⁺ ions via different mechanisms, and the four metal ions can be further discriminated according to their distinct combinational quenching effects onto three fluorescent bands of white-emitting superparticles. In addition, an analytical model was built to enable the simultaneous detection of Cu²⁺, Hg²⁺ and Fe³⁺ in the real sample. Basically, the current work opens the new way to fabricate fluorescent probes with multiple emission bands, which can be easily adapted to prepare more complicated QD encoded fluorescent probes for high throughput detection.