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 m2·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 6 h 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

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 m2·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 6 h 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

Sol-gel synthesis of magnetic TiO2 microspheres and characterization of their in vitro heating ability for hyperthermia treatment of cancer

Common cancer treatments are invasive and lack specificity, leading to unwanted side effects. Because hyperthermia can kill cancer cells and damage proteins and structures within cells, it has been considered a novel, minimally invasive cancer treatment. However, many hyperthermia treatments cannot heat deep-seated tumors effectively and locally. Heat-generating magnetic microspheres can help address this challenge. However, current research has not produced microspheres that can be sufficiently heated. We prepared magnetic titania (TiO2) microspheres by introducing magnetite nanoparticles (MNPs) into the sol–gel process during water-in-oil emulsion for in situ hyperthermia treatment of cancers. Two types of MNPs were used in this study: One type was synthesized by a chemical coprecipitation method, and the other type was commercially available MNPs. The obtained microspheres contained up to 46.7 wt% MNPs, and their saturation magnetization and coercive force were 34.2 emu/g and 103 Oe, respectively. The particles’ in vitro heating efficiency in an agar phantom was measured in an alternating magnetic field of 300 Oe and 100 kHz. The temperature increase in the agar phantom within 300 s was 4.5 °C for microspheres with MNPs that were synthesized by chemical coprecipitation and 53 °C for microspheres with commercially available MNPs. The excellent heating efficiency of the microspheres may be attributed to the hysteresis losses of the magnetic particles. These microspheres are believed to be promising thermoseeds for hyperthermic treatment of cancer

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