TiO2 microspheres containing magnetic nanoparticles for intra-arterial hyperthermia.

Magnetic microspheres measuring 15-35 µm in diameter are believed to be useful for intra-arterial hyperthermia. In this study, we attempted to prepare titanium dioxide (TiO2 ) microspheres containing magnetic nanoparticles (MNPs). MNP-containing TiO2 microspheres with diameters of approximately 30 µm were successfully obtained by sol-gel reaction of titanium tetraisopropoxide in a water-in-oil emulsion with added cosurfactant of 1-butanol and subsequent heat treatment at 200°C. The microspheres showed ferrimagnetism owing to high content of MNPs in approximately 60 wt % and had a low-crystalline TiO2 matrix. Furthermore, the agar phantom was heated to above 43°C after approximately 1 min under an alternating magnetic field of 100 kHz and 300 Oe and showed in vitro biocompatibility similar to that of MNP-free TiO2 microspheres. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2308-2314, 2017.

In vitro apatite formation and drug loading/release of porous TiO2 microspheres prepared by sol-gel processing with different SiO2 nanoparticle contents.

Bioactive titania (TiO2) microparticles can be used as drug-releasing cement fillers for the chemotherapeutic treatment of metastatic bone tumors. Porous anatase-type TiO2 microspheres around 15 µm in diameter were obtained through a sol-gel process involving a water-in-oil emulsion with 30:70 SiO2/H2O weight ratio and subsequent NaOH solution treatment. The water phase consisted of methanol, titanium tetraisopropoxide, diethanolamine, SiO2 nanoparticles, and H2O, while the oil phase consisted of kerosene, Span 80, and Span 60. The resulting microspheres had a high specific surface area of 111.7 m(2)·g(-1). Apatite with a network-like surface structure formed on the surface of the microspheres within 8 days in simulated body fluid. The good apatite-forming ability of the microspheres is attributed to their porous structure and the negative zeta potential of TiO2. The release of rhodamine B, a model for a hydrophilic drug, was rapid for the first 6 h of soaking, but diffusion-controlled thereafter. The burst release in the first 6h is problematic for clinical applications; nonetheless, the present results highlight the potential of porous TiO2 microspheres as drug-releasing cement fillers able to form apatite.