One-pot synthesis and characterization of rhodamine derivative-loaded magnetic core–shell nanoparticles

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2011-05, Vol.13 (5), p.1909-1916
• Main Authors: Zhang, Jin, Li, Jiaxin, Razavi, Fereidoon S., Mumin, Abdul Md
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Inorganic Chemistry; Iron oxides; Lasers; Magnetic properties; Materials Science; Nanoparticles; Nanostructure; Nanotechnology; Optical Devices; Optics; Photonics; Physical Chemistry; Polymerization; Research Paper; Rhodamine; Shells; Silica; Silicon dioxide; Synthesis; X-ray diffraction; X-rays
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-010-9942-1

A new method to produce elaborate nanostructure with magnetic and fluorescent properties in one entity is reported in this article. Magnetite (Fe 3 O 4 ) coated with fluorescent silica (SiO 2 ) shell was produced through the one-pot reaction, in which one reactor was utilized to realize the synthesis of superparamagnetic core of Fe 3 O 4 , the formation of SiO 2 coating through the condensation and polymerization of tetraethylorthosilicate (TEOS), and the encapsulation of tetramethyl rhodamine isothiocyanate-dextran (TRITC-dextran) within silica shell. Transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD) were carried out to investigate the core–shell structure. The magnetic core of the core–shell nanoparticles is 60 ± 10 nm in diameter. The thickness of the fluorescent SiO 2 shell is estimated at 15 ± 5 nm. In addition, the fluorescent signal of the SiO 2 shell has been detected by the laser confocal scanning microscopy (LCSM) with emission wavelength (λ em ) at 566 nm. In addition, the magnetic properties of TRITC-dextran loaded silica-coating iron oxide nanoparticles (Fe 3 O 4 @SiO 2 NPs) were studied. The hysteresis loop of the core–shell NPs measured at room temperature shows that the saturation magnetization ( M s ) is not reached even at the field of 70 kOe (7 T ). Meanwhile, the very low coercivity ( H c ) and remanent magnetization ( M r ) are 0.375 kOe and 6.6 emu/g, respectively, at room temperature. It indicates that the core–shell particles have the superparamagnetic properties. The measured blocking temperature ( T B ) of the TRITC-dextran loaded Fe 3 O 4 @SiO 2 NPs is about 122.5 K. It is expected that the multifunctional core–shell nanoparticles can be used in bio-imaging.