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19 pages, 10429 KiB

Open AccessEditor’s ChoiceArticle

Cell-Biological Response and Sub-Toxic Inflammatory Effects of Titanium Dioxide Particles with Defined Polymorphic Phase, Size, and Shape

by Marina Breisch, Mateusz Olejnik, Kateryna Loza, Oleg Prymak, Nina Rosenkranz, Jürgen Bünger, Christina Sengstock, Manfred Köller, Götz Westphal and Matthias Epple

Nanomaterials 2023, 13(10), 1621; https://doi.org/10.3390/nano13101621 - 12 May 2023

Cited by 8 | Viewed by 1961

Abstract

Six types of titanium dioxide particles with defined size, shape, and crystal structure (polymorphic form) were prepared: nanorods (70 × 25 nm²), rutile sub-microrods (190 × 40 nm²), rutile microspheres (620 nm), anatase nanospheres (100 nm), anatase microspheres (510 nm), and amorphous titania microspheres (620 nm). All particles were characterized by scanning electron microscopy, X-ray powder diffraction, dynamic light scattering, infrared spectroscopy, and UV spectroscopy. The sub-toxic cell-biological response to these particles by NR8383 macrophages was assessed. All particle types were taken up well by the cells. The cytotoxicity and the induction of reactive oxygen species (ROS) were negligible for all particles up to a dose of 100 µg mL⁻¹, except for rutile microspheres which had a very rough surface in contrast to anatase and amorphous titania microspheres. The particle-induced cell migration assay (PICMA; based on chemotaxis) of all titanium dioxide particles was comparable to the effect of control silica nanoparticles (50 nm, uncoated, agglomerated) but did not show a trend with respect to particle size, shape, or crystal structure. The coating with carboxymethylcellulose (CMC) had no significant biological effect. However, the rough surface of rutile microspheres clearly induced pro-inflammatory cell reactions that were not predictable by the primary particle size alone. Full article

(This article belongs to the Special Issue Advances in Nano–Bio Interactions: Nanosafety and Nanotoxicology, Volume II)

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20 pages, 9846 KiB

Open AccessArticle

Microemulsion Derived Titania Nanospheres: An Improved Pt Supported Catalyst for Glycerol Aqueous Phase Reforming

by Andrea Fasolini, Erica Lombardi, Tommaso Tabanelli and Francesco Basile

Nanomaterials 2021, 11(5), 1175; https://doi.org/10.3390/nano11051175 - 29 Apr 2021

Cited by 11 | Viewed by 2596

Abstract

Glycerol aqueous phase reforming (APR) produces hydrogen and interesting compounds at relatively mild temperatures. Among APR catalysts investigated in literature, little attention has been given to Pt supported on TiO₂. Therefore, herein we propose an innovative titania support which can be obtained through an optimized microemulsion technique. This procedure provided high surface area titania nanospheres, with a peculiar high density of weak acidic sites. The material was tested in the catalytic glycerol APR after Pt deposition. A mechanism hypothesis was drawn, which evidenced the pathways giving the main products. When compared with a commercial TiO₂ support, the synthetized titania provided higher hydrogen selectivity and glycerol conversion thanks to improved catalytic activity and ability to prompt consecutive dehydrogenation reactions. This was correlated to an enhanced cooperation between Pt nanoparticles and the acid sites of the support. Full article

(This article belongs to the Special Issue Green Chemistry for Nanoparticle Synthesis)

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14 pages, 6530 KiB

Open AccessArticle

Hybrid TiO₂-ZnO Nanomaterials Prepared Using Laser Ablation in Liquid

by Neli Mintcheva, Shigeru Yamaguchi and Sergei A. Kulinich

Materials 2020, 13(3), 719; https://doi.org/10.3390/ma13030719 - 5 Feb 2020

Cited by 35 | Viewed by 3324

Abstract

Hybrids of semiconductor nanomaterials often demonstrate properties that are superior to those of their components. In this study, we prepared hybrid nanomaterials of TiO₂ and ZnO, which are among the most actively studied semiconductors, by means of millisecond-pulsed laser and analyzed how their morphology, particle size, and surface composition depend on preparation conditions. A series of nanomaterials were obtained via sequentially ablating Zn and Ti metal plates (in different sequences) in water, while laser pulses of lower (2.0 J/pulse) and higher (5.0 J/pulse) energy were applied. The properties of laser-produced hybrid TiO₂-ZnO nanomaterials were shown to be governed by experimental conditions such as laser pulse width, pulse peak power, and reaction media (either pure water or colloid with nanoparticles). The morphology revealed nanospheres of TiO₂ that decorate nanorods of ZnO or flower-like aggregates of zinc oxide. Intriguingly, after extended ablation time, titania was found to be self-doped with Ti³⁺ and Ti²⁺ ions, and the contribution of lower oxidation states of titanium could be controlled by the applied laser pulse energy. The physicochemical characteristics of hybrid nanomaterials were compared with pure ZnO and TiO₂ prepared under the same laser conditions. Full article

(This article belongs to the Section Materials Chemistry)

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24 pages, 5264 KiB

Open AccessFeature PaperArticle

Using Density Functional Theory to Model Realistic TiO₂ Nanoparticles, Their Photoactivation and Interaction with Water

by Daniele Selli, Gianluca Fazio and Cristiana Di Valentin

Catalysts 2017, 7(12), 357; https://doi.org/10.3390/catal7120357 - 24 Nov 2017

Cited by 35 | Viewed by 8309

Abstract

Computational modeling of titanium dioxide nanoparticles of realistic size is extremely relevant for the direct comparison with experiments but it is also a rather demanding task. We have recently worked on a multistep/scale procedure to obtain global optimized minimum structures for chemically stable spherical titania nanoparticles of increasing size, with diameter from 1.5 nm (~300 atoms) to 4.4 nm (~4000 atoms). We use first self-consistent-charge density functional tight-binding (SCC-DFTB) methodology to perform thermal annealing simulations to obtain globally optimized structures and then hybrid density functional theory (DFT) to refine them and to achieve high accuracy in the description of structural and electronic properties. This allows also to assess SCC-DFTB performance in comparison with DFT(B3LYP) results. As a further step, we investigate photoexcitation and photoemission processes involving electron/hole pair formation, separation, trapping and recombination in the nanosphere of medium size by hybrid DFT. Finally, we show how a recently defined new set of parameters for SCC-DFTB allows for a proper description of titania/water multilayers interface, which paves the way for modeling large realistic nanoparticles in aqueous environment. Full article

(This article belongs to the Special Issue Titanium Dioxide Photocatalysis)

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