Abstract

In this paper, we investigated the functional imaging properties of magnetic microspheres composed of magnetic core and CdTe quantum dots in the silica shell functionalized with folic acid (FA). The preparation procedure included the preparation of chitosan-coated Fe3O4 nanoparticles (CS-coated Fe3O4 NPs) prepared by a one-pot solvothermal method, the reaction between carboxylic and amino groups under activation of NHS and EDC in order to obtain the CdTe-CS-coated Fe3O4 NPs, and finally the growth of SiO2 shell vent the photoluminescence (PL) quenching via a Stöber method (Fe3O4-CdTe@SiO2). Moreover, in order to have a specific targeting capacity, the magnetic and fluorescent bifunctional microspheres were synthesized by bonding of SiO2 shell with FA molecules via amide reaction (Fe3O4-CdTe@SiO2-FA). The morphology, size, chemical components, and magnetic property of as-prepared composite nanoparticles were characterized by ultraviolet-visible spectroscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning transmission electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM), respectively. The results show that the magnetic and fluorescent bifunctional microspheres have strong luminescent which will be employed for immuno-labeling and fluorescent imaging of HeLa cells.

Highlights

  • In the past few years, a variety of ferroferric oxide magnetic nanoparticles (Fe3O4 NPs) have been widely used in biomedical applications, such as targeted drug delivery, rapid biological separation, biosensors, and magnetic hyperthermia therapy [1,2,3,4]

  • Luminescent quantum dots (QDs) could serve as luminescent markers, while Fe3O4 NPs could be manipulated under the external magnetic field

  • The pure water was obtained from a Milli-Q synthesis system (Millipore, Billerica, MA, USA)

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Summary

Background

In the past few years, a variety of ferroferric oxide magnetic nanoparticles (Fe3O4 NPs) have been widely used in biomedical applications, such as targeted drug delivery, rapid biological separation, biosensors, and magnetic hyperthermia therapy [1,2,3,4]. Luminescent QDs could serve as luminescent markers, while Fe3O4 NPs could be manipulated under the external magnetic field. Combining QDs and Fe3O4 NPs to get fluorescent/magnetic bifunctional composite nanoparticles has attracted intense attention due to its appealing applications [5,6,7]. The preparation of fluorescent/magnetic bifunctional composite nanoparticles is challenging. We report the synthesis and characterization of Fe3O4-CdTe@SiO2-FA microspheres.

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