Preparation and Characterization of Silica-Coated Magnetic–Fluorescent Bifunctional Microspheres
نویسندگان
چکیده
Bifunctional magnetic-fluorescent composite nanoparticles (MPQDs) with Fe(3)O(4) MPs and Mn:ZnS/ZnS core-shell quantum dots (QDs) encapsulated in silica spheres were synthesized through reverse microemulsion method and characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, vibration sample magnetometer, and photoluminescence (PL) spectra. Our strategy could offer the following features: (1) the formation of Mn:ZnS/ZnS core/shell QDs resulted in enhancement of the PL intensity with respect to that of bare Mn:ZnS nanocrystals due to the effective elimination of the surface defects; (2) the magnetic nanoparticles were coated with silica, in order to reduce any detrimental effects on the QD PL by the magnetic cores; and (3) both Fe(3)O(4) MPs and Mn:ZnS/ZnS core-shell QDs were encapsulated in silica spheres, and the obtained MPQDs became water soluble. The experimental conditions for the silica coating on the surface of Fe(3)O(4) nanoparticles, such as the ratio of water to surfactant (R), the amount of ammonia, and the amount of tetraethoxysilane, on the photoluminescence properties of MPQDs were studied. It was found that the silica coating on the surface of Fe(3)O(4) could effectively suppress the interaction between the Fe(3)O(4) and the QDs under the most optimal parameters, and the emission intensity of MPQDs showed a maximum. The bifunctional MPQDs prepared under the most optimal parameters have a typical diameter of 35 nm and a saturation magnetization of 4.35 emu/g at room temperature and exhibit strong photoluminescence intensity.
منابع مشابه
Facile synthesis of folate-conjugated magnetic/fluorescent bifunctional microspheres
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 group...
متن کاملFacile and Economic Method for the Preparation of Core-Shell Magnetic Mesoporous Silica
In this work core-shell structure Fe3O4@SiO2@meso-SiO2 microsphere has been successfully prepared. An inorganic magnetic core has been coated with multi-shell structure, dense nonporous silica as an inner layer and mesoporous silica as an outer layer. The dense silica shell can enhance the stability and minimize the negative effect of acidic condi...
متن کاملMagnetic amine-functionalized graphene oxide as a novel and recyclable bifunctional nanocatalyst for solvent-free synthesis of pyrano[3,2-c]pyridine derivatives
The new magnetic amine-functionalized graphene oxide (Fe3O4-GO-NH2) nanocatalyst was prepared through the reaction of 3-aminopropyltriethoxysilane (APTES) with magnetic graphene oxide (Fe3O4-GO). It was characterized by XRD, TEM, SEM, FT-IR and EDX techniques. The intrinsic carboxylic acids on the edges of Fe3O4-GO alo...
متن کاملPreparation of Ethylcellulose Coated Gelatin Microspheres as a Multiparticulate Colonic Delivery System for 5-Aminosalicilic Acid
In the long-term management of ulcerative colitis patients, repeat dosing maybe required. Since 5-ASA is largely absorbed from the upper intestine, selective delivery of drugs into the colon may be regarded as a better method of drug delivery with fewer side effects and a higher efficacy. The aim of this study was to prepare and evaluate a double coated multiparticulate system for 5-ASA deliver...
متن کاملPreparation and Characterization of Double Shell Fe3O4 Cluster@Nonporous SiO2@Mesoporous SiO2 Nanocomposite Spheres and Investigation of their In Vitro Biocompatibility
Background: Multifunctional core-shell magnetic nanocomposite particles with tunable characteristics have been paid much attention for biomedical applications in recent years. A rational design and suitable preparation method must be employed to be able to exploit attractive properties of magnetic nanocomposite particles. Objectives: Herein, we report on a simple approach for the synthesis of m...
متن کامل