Organic Silane Modification and Functionalization Research of Fe3O4 Nanoparticles

　　Organic Silane Modification and Functionalization Research of Fe3O4 Nanoparticles
　　The water-solubility and stability of the Fe3O4 nanoparticles have been improved by the surface modification using organic silane. The particles are magnetic-fluorescent composite by encapsulating the fluorescence molecules in the coated SiO2. We also establish modal for the targeted magnetic nanoprobes through conjugating bovine serum albumin (BSA) on the neodymium prices composite particles.The magnetic nanoparticles are covered by the SiO2 produced by tetraethyl orthosilicate (TEOS), which is easily hydrolyzed in the water. After modification, the particles are regular globe, the aggregation of Fe3O4 nanoparticles is decreased, and the particle size can be preliminarily controlled by the adding quantities of TEOS. After choosing the parameters which create proper size and better morphology, the size and uniformity are controlled further. By employing a dropwise addition method, a more uniform and stable system is produced and particle size can be well controlled, then centrifugation and permanent magnet separation are used to remove the biggest and smallest particles. And then particles having narrower distributions and more regular shapes could be obtained.
　　The X-ray diffraction shows that surface modification has no effect on the structure of Fe3O4 nanoparticles. Intensive absorption band of Si-O appears on the Fourier Transform Infrared spectroscopy (FTIR). Isoelectric point and magnetic properties tests indicate that it is possible for the modified particles to stay stable at the PH comparative with the human body; and exhibit superparamagnetic characteristics http://www.999magnet.com/products/142-neodymium-prices with no remanence and coercivity, but the magnetization saturation decreases and the magnetic curves decline just because of the coated SiO2.The fluorescein isothiocyanate (FITC) is composited with 3-aminopropyl-triethoxysilane(APS) as precursors, then the precursors hydrolyse and coat the Fe3O4 cores together with the TEOS. The particles are magnetic-fluorescent composite, and amidocyanogen is introduced onto the particle surface, and then conjugate the BSA molecules. The fluorescence spectra shows that with the increase of the encapsulating fluorescence molecules, the intensity of