Europium-Doped TiO₂ Hollow Nanoshells: Two-Photon Imaging of Cell Binding

Abstract

A simple scalable method to fabricate luminescent monodisperse 200 nm europium doped hollow TiO2 nanoshell particles is reported. Fluorophore reporter, Eu3+ ions, are incorporated directly in the NS matrix, leaving the surface free for functionalization and the core free for payload encapsulation. Amine functionalized polystyrene beads were used as templates, and the porous walls of europium doped titania nanoshells were synthesized using titanium(IV) t-butoxide and europium(III) nitrate as reactants. X-ray diffraction analysis identified anatase as the predominant titania phase of the rigid nanoshell wall structure, and photoluminescence spectra showed that the Eu(III) doped TiO2 nanoshells exhibited a red emission at 617 nm due to an atomic f-f transition. Nanoshell interactions with HeLa cervical cancer cells in vitro were visualized using two-photon microscopy of the Eu(III) emission, and studied using a luminescence ratio analysis to assess nanoshell adhesion and endocytosis.

Unconventional tailorable patterning by solvent-assisted surface-tension-driven lithography

“…The confinement of the molecular material under the template mesh may also result from a combination of Brownian motion and Van der Waals interactions in the solvent [41]. Also changes in the surface tension and polarity of the solvent are due to the interaction between the specific parameters of the solution and the two solid interfaces (glass and the Cu grid) inducing Bénard-Marangoni instabilities in the liquid films [9][10][11][12]. Obviously, this indicates that the radius R of the formed nanoparticles depends on the starting film thickness h. Specifically, larger h will imply a larger R (as the law R / p h) [42].…”

“…Besides, embedding a lanthanide complex in a hybrid matrix is also favorable for its unique optical properties such as long fluorescence lifetime and good luminescence efficiency combined with high photochemical stability of the hosts. Furthermore, titania is an excellent material for Eu 3+ being highly transparent to visible light and due to its thermal, chemical, and mechanical properties and several synthetic approaches of Eu 3+ doped TiO 2 films, nanoparticles, and particles have been reported [9][10][11][12]. The ability to pattern functional materials at different length scales is therefore essential for many research fields including electronic and optoelectronic devices [13,14].…”

Biomedical applications of nano-titania in theranostics and photodynamic therapy

“…180,181 However, Wataha et al reported the successful delivery of MST metal ions to monocytes and fibroblast cells, and affected the cellular functionality. 184 This system could provide scaffolds for cancer theranostics if the anticancer agent is coupled with the TiO 2 nanoshells. However, later on it was found that it can be efficiently bound to biologically active metals.…”

Lanthanide‐doped hollow nanomaterials as theranostic agents

“…Last step is calcination process, which has a dual function: the removal of carbon spheres cores and formation of hollow crystalline structures from Ln(OH)CO 3 precursor layer. Besides carbon spheres, other hard templates (polystyrene, silica spheres, and melamine formaldehyde) are also applied for the fabrication of hollow spheres –,, , …”