Multifunctional Gadolinium‐Doped Mesoporous TiO₂ Nanobeads: Photoluminescence, Enhanced Spin Relaxation, and Reactive Oxygen Species Photogeneration, Beneficial for Cancer Diagnosis and Treatment

Abstract

Materials with controllable multifunctional abilities for optical imaging (OI) and magnetic resonant imaging (MRI) that also can be used in photodynamic therapy are very interesting for future applications. Mesoporous TiO sub-micrometer particles are doped with gadolinium to improve photoluminescence functionality and spin relaxation for MRI, with the added benefit of enhanced generation of reactive oxygen species (ROS). The Gd-doped TiO exhibits red emission at 637 nm that is beneficial for OI and significantly improves MRI relaxation times, with a beneficial decrease in spin-lattice and spin-spin relaxation times. Density functional theory calculations show that Gd ions introduce impurity energy levels inside the bandgap of anatase TiO , and also create dipoles that are beneficial for charge separation and decreased electron-hole recombination in the doped lattice. The Gd-doped TiO nanobeads (NBs) show enhanced ability for ROS monitored via OH radical photogeneration, in comparison with undoped TiO nanobeads and TiO P25, for Gd-doping up to 10%. Cellular internalization and biocompatibility of TiO @xGd NBs are tested in vitro on MG-63 human osteosarcoma cells, showing full biocompatibility. After photoactivation of the particles, anticancer trace by means of ROS photogeneration is observed just after 3 min irradiation.

Porous NiTiO3/TiO2nanostructures for photocatatalytic hydrogen evolution

“…Ni-doped TiO2 (TiO2:Ni) nanostructures were produced from the hydrothermal decomposition of titanium(IV) isopropoxide in the presence of proper amounts of nickel(II) nitrate hexahydrate, HDA as a shape-directing agent and KCl to control the ionic strength of the solution (see experimental section for details and Figure S2 for SEM images). 32 As shown by TEM characterization, the size and shape of the nanostructures obtained from this hydrothermal reaction strongly depended on the amount of Ni introduced ( Figure S3). In the absence of Ni, nanoparticles with an average size around 50 nm and mostly irregular shapes, although some elongated, were obtained.…”

Temperature dependent photoluminescence of anatase and rutile TiO2 single crystals: Polaron and self-trapped exciton formation

“…That can be explained by a higher density of oxygen vacancies in the former, that shows no regions without defects where STE would be free to move and hop onto any place. As has been shown for Gd-doped TiO 2 , 45 density functional theory (DFT) calculations allowing to determine precisely the exact nature of the defect level that are involved in the carrier dynamics and to give their energy position and spin configuration would be very valuable for the understanding energy relaxation properties of titania.…”

The role of membrane vesiculation and encapsulation in cancer diagnosis and therapy

“…Morphological and structural characterization of these TiO 2 @xGd NBs revealed the formation of monodispersed mesoporous spheres in anatase phase only for un-doped TiO 2 NBs, TiO 2 @5%Gd NBs, and TiO 2 @10%Gd NBs (Fig. 9) [8].…”

“…Recently, Imani et al reported on gadolinium-doped TiO 2 nanobeads (TiO 2 @Gd NBs) that exhibit simultaneous OI-MRI properties as well as enhanced ROS photo-generation capacities [8]. Multifunctional TiO 2 @ xGd NBs (here, x denotes the gadolinium molar ratio: 0, 5, 10, 15, 20%) were synthesized via a solvothermal method that was similar to the procedure used in the production of TiO 2 MBs.…”

“…Next, we discuss a recently reported nanoparticle therapy which integrates therapeutics with diagnostics e also known as theranostics e using multifunctional mesoporous gadolinium-doped TiO 2 nanobeads (Gd@ titania NBs) possessing a high degree of stability and biocompatibility. We will see that Gd@titania NBs form a fully biocompatible system for optical imaging (OI), magnetic resonance imaging (MRI) and selective ROS (anticancer agent) photo-generation inside the cancer cells, providing impressive multi-functionality and allowing for simultaneous OI-MRI and photodynamic therapy (PDT) without compromising the advantages of either component [8]. The endocytosis of these in cancerous cells NBs is evaluated with the aid of numerical (Monte Carlo) and experimental results, demonstrating that cellular internalization is directly linked to physical properties of cell membranes [9].…”