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

Abstract

A novel multifunctional microsphere with a fluorescent CdTe quantum dots (QDs) shell and a magnetic core (Fe(3)O(4)) has been successfully developed and prepared by a combination of the hydrothermal method and layer-by-layer (LBL) self-assembly technique. The resulting fluorescent Fe(3)O(4)@C@CdTe core/shell microspheres are utilized as a chemosensor for ultrasensitive Cu(2+) ion detection. The fluorescence of the obtained chemosensor could be quenched effectively by Cu(2+) 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 (R(2) = 0.9957) in the range 1-10 μM with a quenching constant (K(sv)) of 4.9 × 10(4) M(-1). Most importantly, magnetic measurements showed that the Fe(3)O(4)@C@CdTe core/shell microspheres were superparamagnetic and they could be separated and collected easily using a commercial magnet in 10 s. These results obtained not only provide a way to solve the embarrassments in practical sensing applications of QDs, but also enable the fabrication of other multifunctional nanostructure-based hybrid nanomaterials.

Synthesis and applications of multifunctional composite nanomaterials

“…A nanosphere lithography strategy combined with surface chemistry enables the production of arrays of β-NaYF 4 : Yb,Er nanorings inlaid in an octadecyltrichlorosilane matrix. Wang et al (2011) fabricated multifunctional magnetic and luminescent Fe 3 O 4 @C@CdTe core/shell microspheres (Figure 7) that act as a new type of synthetic fluorogenic chemosensor for probing Cu 2+ ions in aqueous solutions. The resulting nanosensor exhibits a high sensitivity to Cu 2+ ions over the other competing metal ions tested in water.…”

Preparation of Fe3O4@C@CNC multifunctional magnetic core/shell nanoparticles and their application in a signal-type flow-injection photoluminescence immunosensor

“…The Fe 3 O 4 @C nanoparticles were firstly prepared by a method reported previously [16]. To prepare the Fe 3 O 4 @C@CNCs, the surface of Fe 3 O 4 @C should be endowed with positive charges.…”

“…With the help of the negative charge on the surface of Fe 3 O 4 @C [16] and the poly(dimethyldiallyl ammonium chloride) (PDDA) polyelectrolyte cross-linker, CNCs can be easily assembled on the surface of Fe 3 O 4 @C, producing Fe 3 O 4 @C@CNC nanoparticles.…”

Coaxial electrospinning preparation and properties of magnetic–photoluminescent bifunctional CoFe2O4@Y2O3:Eu3+ coaxial nanofibers

“…Presently, studies are mainly focused on the preparation, properties and applications of magneticphotoluminescent bifunctional nanoparticles [23][24][25]. In order to obtain new morphologies of magnetic-fluorescent nanomaterials, the fabrication of one-dimensional magnetic-fluorescent nanomaterials is an urgent subject of study.…”