Layer-by-Layer Assembled Fe3O4@C@CdTe Core/Shell Microspheres as Separable Luminescent Probe for Sensitive Sensing of Cu2+ Ions

A novel multifunctional microsphere with a fluorescent CdTe quantum dots (QDs) shell and a magnetic core (Fe3O4) has been successfully developed and prepared by a combination of the hydrothermal method and layer-by-layer (LBL) self-assembly technique. The resulting fluorescent Fe3O4@C@CdTe core/shell microspheres are utilized as a chemosensor for ultrasensitive Cu2+ ion detection. The fluorescence of the obtained chemosensor could be quenched effectively by Cu2+ ions. The quenching mechanism was studied and the results showed the existence of both static and dynamic quenching processes. However, static quenching is the more prominent of the two. The modified Stern–Volmer equation showed a good linear response (R2 = 0.9957) in the range 1–10 μM with a quenching constant (Ksv) of 4.9 × 104 M–1. Most importantly, magnetic measurements showed that the Fe3O4@C@CdTe core/shell microspheres were superparamagnetic and they could be separated and collected easily using a commercial magnet in 10 s. These results ob...