A Simple and “Green” Method for Synthesis of Magnetic Hollow Silica Spheres and Its <sup>99</sup>Tc<sup>m</sup> Labeled Targeting Studies

Abstract

The magnetic hollow silica spheres (MHSS) with uniform cavity size and shell thickness were prepared by a simple and "green" method using functionalized SiO 2 spheres as templates. Magnetic particles (Fe 3 O 4 ) were deposited on the SiO 2 surface by varying the molar ratio of [Fe 2+ ]/ [Fe 3+ ] and the molar concentration of iron salts. The obtained magnetic hollow silica spheres exhibited a super-paramagnetic behavior at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder scattering (XRD) were applied to characterize the MHSS. Besides, their unit cell parameters are calculated according to results indexing to XRD, the MHSS sample prepared at 0.10 M iron salts and 2:1 molar ratio of [Fe 2+ ]/ [Fe 3+ ] has a largest cell angle (β) of unit cell. Due to large hollow cavity space and super-paramagnetic characteristics, the inner amino-functionalized MHSS could be labeled with radioisotope 99 Tc m to study the MHSS's magnetic targeting distribution in vivo. These results indicate that the MHSS has potential in the magnetic targeted drug delivery system which reduces the damage to normal cells and improves the therapeutic effect of cancer.

Fabrication of TiO2 Spheres and a Visible Light Active α-Fe2O3/TiO2-Rutile/TiO2-Anatase Heterogeneous Photocatalyst from Natural Ilmenite

“…The molar ratio of Fe 2+ and Fe 3+ was very important in determining the magnetism of the synthesized magnetite nanoparticles. 51 Therefore, to completely oxidize Fe 2+ to Fe 3+ , oxygen gas was bubbled through the acid leachate, and the resulting solution contained Fe 3+ as FeCl 3 and Ti 4+ present as H 2 TiOCl 4 or TiOCl 2. The total Fe 3+ and Ti 4+ concentrations were determined by ICP-MS and were found to be 5434 and 3078 mg/L, respectively.…”

“…However, it is virtually impossible to determine the exact Fe 2+ and Fe 3+ ion concentration of acid leachate as Fe 2+ readily oxidizes to Fe 3+ in the presence of O 2 dissolved in the medium and that is present in the atmosphere as shown in eq . The molar ratio of Fe 2+ and Fe 3+ was very important in determining the magnetism of the synthesized magnetite nanoparticles . Therefore, to completely oxidize Fe 2+ to Fe 3+ , oxygen gas was bubbled through the acid leachate, and the resulting solution contained Fe 3+ as FeCl 3 and Ti 4+ present as H 2 TiOCl 4 or TiOCl 2.…”