Luminomagnetic Silica-Coated Heterodimers of Core/Shell FePt/Fe₃O₄ and CdSe Quantum Dots as Potential Biomedical Sensor

Abstract

We report the synthesis of a new multifunctional nanomaterial based on silica-coated FePt/Fe 3 O 4 -CdSe heteronanostructures, combining luminescent and magnetic properties in a promising bifunctional sensor for biomedical applications. Spherical Fe 3 O 4 -coated FePt (FePt/Fe 3 O 4 ) superparamagnetic nanoparticles (10.8 ± 1.5 nm) with high saturation magnetization and controlled size and shape were obtained using thermal decomposition coupled with seed-mediated growth method. Luminescent property was added to the nanomaterial by using the FePt/Fe 3 O 4 magnetic core as seed and growing the CdSe quantum dots (2.7 ± 0.6 nm) onto its surface in a heterodimer-like structure using the hot-injection approach. The FePt/Fe 3 O 4 -CdSe luminomagnetic heteronanostructures were coated with silica shell using the reverse-micelle microemulsion route to avoid solvent-quenching effects. After silica coating, the water-dispersible heteronanostructures showed a diameter of 25.3 ± 2 nm, high colloidal stability, magnetic saturation of around 11 emu g −1 , and photoluminescence in the blue-green region, as expected for potential bifunctional platform in biomedical applications. The saturation magnetization of heteronanostructures can be increased to 28 emu g −1 by annealing at 550 ∘ C due to the presence of the FePt phase.

Synthesis and Modification of Magnetic Nanoparticles for Biosensing and Bioassay Applications: A Review

“…The resulting Fe@Au nanoparticles exhibit excellent stability even in the air after magnetic separation, indicating a proper coating of the largely reactive iron core by the Au shell. Furthermore, the same technique was employed to develop a new type of multifunctional nanomaterial, FePt/Fe 3 O 4 -CdSe heteronanostructures coated in silica, which displayed both luminescent and magnetic properties [64]. The reverse micelle microemulsion technique was used to coat the heteronanostructures, combining magnetic and luminescent properties, making them water dispersible, highly colloidally stable, and capable of emitting photoluminescence in the blue-green region.…”

Synthetic Approaches to Colloidal Nanocrystal Heterostructures Based on Metal and Metal-Oxide Materials

“…To pursue enhanced functionality, there have been efforts toward SiO 2 -protected CNHS systems integrating magnetic and fluorescent materials. One example is represented by a complex FePt@Fe 3 O 4 -CdSe@SiO 2 system, which was constructed starting from spherical FePt@Fe 3 O 4 core@shell CNHSs [ 162 ]. The heterostructure seeds were first decorated with tiny CdSe nanocrystal satellites and then coated with SiO 2 shell in a reverse-micelle microemulsion to minimize solvent-induced quenching of the CdSe photoluminescence [ 162 ].…”