Anatase nano-TiO2 Research Articles

Self-cleaning and anti-corrosion superhydrophobic coatings of PA-TiO2@SiO2 copolymerized hetero compound

Inspired by leaf lotus effect, superhydrophobic surfaces have developed rapidly in recent years. In this paper, anatase nano TiO2 with particles size of about 70 nm was successfully loaded on the surface of SiO2 by sol-gel method. SiO2 and TiO2 were chemically bonded by Ti-O-Si and constructed a certain micro- and nano-composite structure. After superhydrophobic composite PA-TiO2@SiO2 was obtained by copolymerizing with acrylate and other monomers. The coating was prepared by drop coating plus spraying coating on glass substrates with water contact angles >160° and excellent self-cleaning properties, which could maintain the performance of the superhydrophobic coating by immersion in acidic solutions or water for 2 days. Meanwhile, the coating on the surface of the glass plate at −20 °C significantly delayed the freezing time of the ice. The rough structure of the surface and the presence of fluorine-containing hydrophobic groups gave the superhydrophobic coating an advantage over acrylate polymers in reducing the corrosion rate of steel surfaces.

Preparation of super hydrophilic-underwater super oleophobic photoinduced self-cleaning Al2O3 @TiO2 ceramic membrane and separation performance of oil-in-water emulsion

Membrane hydrodynamic irreversible oil fouling is a pressing issue. Here, an antifouling Al2O3 @TiO2 membrane with excellent wettability was created using the sol-gel method to create an anatase nano-TiO2 coating on the surface of an Al2O3 ceramic membrane. Analyzing the separation performance of an Al2O3 @TiO2 membrane on simulated oily emulsions determined the amount of TiO2 covered on the membrane surface (0.8 mol·L−1). Under the synergy of hydrophilic nano-TiO2 and ultraviolet (UV) light, the Al2O3 @TiO2 membrane demonstrated improved wettability and self-cleaning ability and maintained favorable separation performance (769.23 L·m−2·h−1, 97.75%, 1.23 mg·L−1) after 6 h of continuous separation of the actual oilfield produced water. After 30 min of UV illumination, the membrane flux recovered completely. This is due to the fact that the active substances (eg.,·OH,·O2, and 1O2) generated in situ on TiO2 on the membrane surface after UV illumination weakened the interaction of membrane surface fouling, resulting in less oil fouling. In addition, the Al2O3 @TiO2 membrane maintained extremely outstanding oil resistance stability and recoverability during high-intensity hydraulic flushing and 25 cycles of testing. This study provides a theoretical basis for the engineering application of ceramic membranes in oilfield-produced water treatment.

Multi-functional TiO2-based nanocomposite coating with durable superhydrophobicity and enhanced photocatalytic and antimicrobial properties for the sustainable maintenance of building stones

Superhydrophobic surfaces have demonstrated great potential in fundamental research and functional applications, yet their durability and antimicrobial property shall be improved. To mitigate the degradation of building stones, which severely undermines the safety, economic and aesthetic value of contemporary and historical constructions, a superhydrophobic coating endowed with photocatalytic and antimicrobial properties is presented. The nanocomposite (Si-PFE-TiO2) was obtained by covalently connecting TiO2 nanoparticles with a fluorinated siloxane via Ti-O-Si linkages. To apply, superhydrophobic surfaces can be effortlessly prepared by brushing/deposing the alcoholic suspension of Si-PFE-TiO2 on substrates. Upon protective performance and physiochemical compatibility evaluation, with a very low amount applied (8.5 g/m2), Si-PFE-TiO2 coating exhibited much higher water inhibition efficiency, residual vapor diffusivity while less surface chromatic changes, compared with three reference coatings (TiO2-fluoroelastomer formulations). Owing to the Ti-O-Si linkages which improve photon efficiency and stimulate the oxidation process, Si-PFE-TiO2 coating showed enhanced photoactivity and antibacterial action. The degradation efficacy of colorants on Si-PFE-TiO2 coating was>1.6 times higher than reference coatings. Considering the amount of TiO2 incorporated in Si-PFE-TiO2 (∼0.92 g/m2), its photoactivity outperforms other recently reported TiO2-containing coatings. Moreover, compared with anatase nano-TiO2, Si-PFE-TiO2 coating showed higher antimicrobial effects against Gram-positive and Gram-negative bacteria, being 1.94, 1.32 times higher for E. Coli and 1.93, 1.59 times higher for S. aureus, with the concentration 0.5 g/L and 1.2 g/L, respectively. Lastly, Si-PFE-TiO2 coating is also chemically and mechanically robust, enabling application in harsh conditions. This study sheds light on designing multi-functional superhydrophobic surfaces for in-situ and outdoor applications.

Pb(II) Uptake from Polluted Irrigation Water Using Anatase TiO2 Nanoadsorbent.

The adsorption characteristics of titanium dioxide nanoparticles (nano-TiO2) for the removal of Pb(II) from irrigation water were investigated in this work. To accomplish this, several adsorption factors, such as contact time and pH, were tested to assess adsorption efficiencies and mechanisms. Before and after the adsorption experiments, commercial nano-TiO2 was studied using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The outcomes showed that anatase nano-TiO2 was remarkably efficient in cleaning Pb(II) from water, with a removal efficiency of more than 99% after only one hour of contact time at a pH of 6.5. Adsorption isotherms and kinetic adsorption data matched the Langmuir and Sips models quite well, showing that the adsorption process occurred at homogenous sites on the surface of nano-TiO2 by forming a Pb(II) adsorbate monolayer. The XRD and TEM analysis of nano-TiO2 following the adsorption procedure revealed a non-affected single phase (anatase) with crystallite sizes of 9.9 nm and particle sizes of 22.46 nm, respectively. According to the XPS data and analyzed adsorption data, Pb ions accumulated on the surface of nano-TiO2 through a three-step mechanism involving ion exchange and hydrogen bonding mechanisms. Overall, the findings indicate that nano-TiO2 has the potential to be used as an effective and long-lasting mesoporous adsorbent in the treatment and cleaning of Pb(II) from water bodies.

Nano-TiO2 coated needle carbon fiber reinforced phenolic aerogel composite with low density, excellent heat-insulating and infrared radiation shielding performance

High-performance thermal protection materials (TPMs) for spacecraft are becoming current research hotspots. Lightweight polymer-based ablators are considered to be the most promising candidates for TPMs due to their excellent designability and versatility. In this study, a unique nano-TiO2 coated needled carbon fiber felt/phenolic resin aerogel composite (TiCF/PR) is reported. Wherein the anatase nano-TiO2 was in-situ coated on the surface of carbon fibers uniformly through the sol-gel and calcination method, then, the phenolic resin aerogel was in-situ synthesized in the nano-TiO2 coated needled carbon fiber felt (TiCF) preform through vacuum impregnation and solvothermal method. The as-prepared aerogel composite possesses a low density (0.30–0.32 g/cm3), low thermal conductivity (0.034 and 0.312 W/(m K) in the z and xy directions), and excellent thermal stability with 13.86% residual weight at 1300 °C in air. It is worthwhile to note that the TiCF/PR composite exhibits excellent antioxidant ablation and infrared (IR) radiation shielding properties in a high-temperature heating environment. With an oxygen-acetylene blaze heating of 1.5 MW/m2 for 150 s, the linear ablation rates decreased by 13.4%, and the backside temperature reduced from 322.3 to 179.1 °C compared to that of the sample without nano-TiO2 coating. The experimental and theoretical analysis showed that the present TiCF/PR nanocomposite has competitive and potential application prospects in the field of future TPMs.

Fabrication of a Potential Electrodeposited Nanocomposite for Dental Applications

In the present study, a nanocrystalline Ni-Fe matrix with reinforced TiO2 nanoparticles as a functional nanocomposite material was fabricated by pulsed current electroforming in UV-LIGA (lithography, electroplating, and molding). The influences of TiO2 nanoparticles on the Ni-Fe nanocomposite deposition were also investigated using scanning electron microscopy, transmission electron microscopy, and in vitro cytotoxicity assay. It was found that the Ni-Fe nanocomposite with 5 wt.% TiO2 nanoparticles showed a smooth surface and better dispersion property. When the Ni-Fe nanocomposite is combined with 20 wt.% TiO2, it resulted in congeries of TiO2 nanoparticles. In addition, TiO2 nanoparticles possessed better dispersion properties as performed in pulse current electrodeposition. The microstructure of the electrodeposited Ni-Fe-TiO2 nanocomposite was a FeNi3 phase containing anatase nano-TiO2. Moreover, the electrodeposited Ni-Fe-5 wt.% TiO2 nanocomposite exhibited a smooth surface and structural integrity. Cytotoxicity assay results also proved that the Ni-Fe nanocomposite with different concentrations of TiO2 nanoparticles had good biocompatibility. Therefore, the optimization of pulse current electroforming parameters was successfully applied to fabricate the Ni-Fe-TiO2 nanocomposite, and thus could be used as an endodontic file material for dental applications.

Interaction of CO2 with TiO2/reduced graphene oxide as superior catalysts: Dispersion-corrected density functional theory simulation

Interaction of CO2 with the anatase TiO2 slab, nano-TiO2 cluster and nano-TiO2/reduced graphene oxide (rGO) was explored by density functional theory simulations. Two orientations, namely (001) and (100) directions, were examined for an approaching CO2 molecule to the surfaces. The energetically favorable state corresponds to a CO2 molecule adsorbed in the (001) direction for all the considered substrates. The interaction energies of adsorbed CO2 on the TiO2 slab, nano-TiO2 cluster, and nano-TiO2-rGO (on the nano-TiO2 cluster attached to the rGO) surfaces were determined to be about −5.007, −11.643, and −13.025 kcal/mol, respectively. Interaction properties were identified by the high-level MP2 calculations and the AIM theory analysis. Finally, for the adsorbed CO2 on the nano-TiO2-rGO, density-functional tight-binding (DFTB) molecular dynamics simulation were carried out and the results showed that CO2 absorption strength was enhanced on the (001) nano-TiO2 at room temperature by bonding of either O atom or C atom to the surface Ti and O atoms. It is found that nano-TiO2-rGO was more effective for CO2 adsorption than both the bulk TiO2 slab and free nano-TiO2 cluster.

Morphological, spectral and toxicological features of new composite material of titanium nanodioxide with nanosilver for use in medicine and biology

The results of this study indicate that titanium dioxide nanoparticles (nano-TiO2) possess adsorptive, photocatalytic, bactericidal, virucidal and fungicidal properties, which are used in antibacterial coating, for air and water disinfection. In parallel with studies of the physicochemical characteristics of titanium dioxide, its toxicological assessment was carried out to prevent possible harmful effects on humans and the biosphere objects, followed by an assessment of the nano-TiO2 hazard class. To enhance these useful properties of nano-TiO2, nanopowders of titanium dioxide and a composite of titanium dioxide were synthesized with a silver (nano-TiO2 /Ag) by way of chemical precipitation of metatitanic acid adding silver nitrate to the composite at 500-600°C. It was stated that the synthesized nanostructures have the following characteristics: anatase crystal structure of TiO2 (anatase, rutile, brookite – natural crystalline modifications of TiO2), the size of Ag nanoparticles is 35-40 nm, TiO2 – 13-20 nm. Nanocomposite has surface defects of the crystal lattice (oxygen vacancies, impurities, excess electrons or holes), silver nanoparticles are localized on the surface of anatase TiO2, which increases adsorptive, photocatalytic, biological and specifically antibacterial properties of the composite material nano-TiO2/Ag. According to the parameters of acute intraperitoneal toxicity, the studied nanocomposite anatase nano-TiO2/Ag was classified as a moderately dangerous substance (material). Nano-TiO2 and TiO2/Ag nanocomposites do not cause local irritation to the skin, yet have a mildly irritating effect on the mucous membrane of the eye, and are also characterized by a weak sensitization effect.

Visible-light-driven photocatalysis over nano-TiO2 with different morphologies: From morphology through active site to photocatalytic performance

Enormous efforts have been devoted to exploring the influence of the materials’ morphology on photocatalytic performance, while the role of active site between them attracts less attention. Herein, three types of anatase nano-TiO2 with different morphologies were successfully prepared for visible-light-driven photocatalytic selective oxidation of benzylamine. The material properties of the samples were systematically studied by various characterization techniques such as XRD, SEM, TEM, AFM, XPS, UV–vis DRS, ESR and in situ FTIR. Due to possessing clear advantages especially for having more active sites (coordinatively unsaturated Ti atoms and oxygen vacancies), the TiO2 with porous structure shows more excellent photocatalytic performance than the other samples. Coordinatively unsaturated Ti atoms can chemisorb and activate benzylamine molecules via forming H-N…Ti coordination species, whose absorption property of visible light guarantees that TiO2 samples can achieve the photocatalytic process under visible light. Oxygen vacancies can chemisorb and activate oxygen molecules to form reactive oxygen species (superoxide radical) by the reduction of photogenerated electrons. Finally, a possible synergetic mechanism based on the interaction of reactants and catalyst interfaces was proposed at the molecular level to illustrate the photocatalytic process.

Evaluation of arsenic sorption performance using dendritic anatase and polycrystalline rutile nano-TiO2 for environmental applications

Two synthetic nano-TiO2-based materials, aggregated dendritic anatase nano-TiO2 and polycrystalline rutile nano-TiO2 attached to the surface of SiO2, were analyzed and compared for geo-environmental engineering applications. Characterization of crystal structure, purity, and morphologic, microscopic features of the materials were examined by X-ray powder diffraction, X-ray fluorescence, and scanning electron microscope, respectively. Arsenic removal rates/efficiencies were compared between the two materials in different settings for laboratory batch experiment. The adsorption curve on arsenic was obtained. Subsequently, different concentrations of arsenic solutions were injected in batches at different flow rates 0.67, 0.83, 1.00, 1.25, 1.67, 2.50, 5.00, and 10.00 ml/min to simulate field conditions. Results show that both of TiO2-based materials demonstrate outstanding capabilities for arsenic removal. Removal rates are 83% (± 0.025) and 95% (± 0.024) for aggregated TiO2, while 82% (± 0.031) for 93% (± 0.013) for attached TiO2. Results suggest that attached form of TiO2 is more effective for arsenic removal under fast groundwater flow condition, while aggregated form TiO2 can be suitable for high arsenic concentration and low water flow rate. Both materials are considered cost-effective as both can be recovered and reused after regeneration process.

The NOx Degradation Performance of Nano-TiO2 Coating for Asphalt Pavement.

The NOx degradation performance of nano-TiO2 as a coating material for the road environment was evaluated in this research. The nano-TiO2 coating materials for both road surface and roadside were prepared by using anatase nano-TiO2, activated carbon powder, silane coupling agent and deionized water. The impact of varying amounts of coating material and silane coupling agent were evaluated. The road environment of NOx degradation was simulated by the photocatalytic test system designed by the research team. For the road surface coating, the photocatalytic degradation experiments of NO under different radiation intensities were carried out. The results show that the material has good photocatalytic degradation performance, and the proper amount of silane coupling agent can enhance the bonding performance of the material and asphalt mixture. For the roadside coating, sodium dodecylbenzene sulfonate was selected as the surfactant to carry out the photocatalytic degradation experiment of NO2 with different dosages of surfactant. The results showed that when the mass ratio of nano-TiO2 and surfactant was about 1:2, the catalytic degradation effect of the material was the best.

Effect of nanosized anatase TiO2 on germination, stress defense enzymes, and fruit nutritional quality of Abelmoschus esculentus (L.) Moench (okra)

Due to wide-scale generation/use of titanium dioxide (TiO2) nanoparticles, significant release into agricultural soil is inevitable. This has caused great ecotoxicological concern due to their unclear fate in plants, most especially food crops. This study aimed to compare the impact of anatase nano-TiO2 of two primary diameters (nTiO2 [50 nm] and bTiO2 [68 nm]) on stress enzymes and seed nutritional quality of okra (Abelmoschus esculentus) plant. Compared to control, bTiO2 significantly promoted seed germination in okra while chlorophylls were only enhanced significantly by nTiO2 and reduced by bTiO2. The results of biochemical experiments implied that both nano-TiO2 particles significantly reduced ascorbate peroxidase (APX) and glutathione reductase (GR) activity levels in roots. Conversely in leaves, APX activity level was significantly reduced by the both nano-TiO2 particles, while GR activity was promoted. Interestingly, both nano-TiO2 particles significantly increased superoxide dismutase activity in roots and leaves, indicating that nano-TiO2 induced toxicity to okra plant. The accumulation of malondialdehyde in leaves was significantly high in okra plants exposed to bTiO2, and this underpins the fact that the large-sized nano-TiO2 portends phytotoxicity to the leaves. In this study, the degree of response of stress enzymes to nano-TiO2 was particle size. Fruit quality analysis indicated a decrease in Ca, Mg, and Fe contents which was particle size–dependent and dose-dependent. In addition, the proximate compositions (except carbohydrate) of fruits were all negatively altered by both nano-TiO2 particles. Conclusively, the results suggest that particle size is a factor in the phytotoxicity and the individual effect of both nano-TiO2 particles on okra plant was dose-dependent.

Preparation of nano-TiO2 composite photocatalytic material and its degradation performance on aldehydes

Chitosan-TiO2 photocatalytic composite was prepared using anatase nano-TiO2 and edible chitosan. Fourier Transform Infrared Spectroscopy (FT-IR), ultraviolet visible (UV-vis) and scanning electron microscopy (SEM) was used to characterize the structure of the composites. The photocatalytic degradation performance of the composites was studied by constructing a simulation system. The stability of the combination between chitosan and TiO2 in the composite can be confirmed by the results of FT-IR, UV-vis and SEM. The composite had a good photocatalytic degradation effect. When the addition amount of chitosan-TiO2 was 0.4%, the degradation efficiency of heptanal, octanal, (E)-2-heptenal and (E)-2-octenal reached the highest values of 83.82%, 81.73%, 96.33% and 93.36%, respectively.

Effects of particle size, crystal phase and surface treatment of nano-TiO2 on the rheological parameters of cement paste

In this study, two sizes of rutile nano-TiO2 (NT) (20 nm and 50 nm), three crystal phases of NTs (anatase NT, rutile NT and polymorphic NT, a hybrid of 80% anatase NT and 20% rutile NT) and two surface-treated NTs (SiO2-coated NT and SiO2/Al2O3-coated NT) were employed to their effect on rheological behaviors of cement pastes. The water-to-cement ratio was fixed at 0.24, and the NTs were added to the paste at contents of 0, 0.1%, 0.3%, 0.5%, 0.7% and 1.4 vol% of cement, respectively. The rheological behaviors of cement pastes were characterized using two rheological parameters including yield stress and minimum viscosity. The H-B model was chosen to calculate the yield stress and the minimum viscosity was selected as the smallest apparent viscosity in the apparent viscosity-shear rate curve. Experimental results show that NTs have a significant effect on the rheological parameters of the cement pastes when the NT content exceeds 0.5 vol%. The yield stress and minimum viscosity of the cement pastes varies with NT particle size by changing the total surface area of the system. The rutile NT with smaller particle size produces larger yield stress and the minimum viscosity. Cement pastes with three different crystal phases of NTs show distinct rheological behaviors. The cement paste with the rutile NT has the largest yield stress and minimum viscosity, while cement paste with the polymorphic NT has the smallest yield stress and minimum viscosity. The yield stress and the minimum viscosity of the cement paste with SiO2/Al2O3-coated NTs are larger than those of the cement paste with SiO2-coated NTs owing to a smaller electrostatic repulsion.

Preparation and photocatalytic property of electrospun nano-TiO2/poly(methylmethacrylate) nanofibres

Nano-TiO2/poly(methylmethacrylate) nanofibres were prepared by electrospinning with poly(methylmethacrylate) (PMMA) and anatase nano-TiO2 as main materials which were blended mechanically and dissolved in dimethylformamide (DMF) and ethyl ethanoate (EA) solvent. The nanofibres morphologies and physical states were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry analysis (TG), fourier transform infrared (FTIR) spectroscopy and UV–visible (UV–Vis) spectroscopy. Scanning electron microscopy observations revealed that when the content of TiO2 was 5%, nano-TiO2/poly(methylmethacrylate) nanofibres had the minimum average diameter which was 409 nm. Results from FTIR, XRD and TG suggested that anatase nano-TiO2 had been successfully introduced to the PMMA matrix and TiO2/PMMA nanofibres had good thermal stability within 300 °C. Results from UV–Vis suggested that when 10% of anatase nano-TiO2 was added, the photocatalytic decomposition of methyl orange was 50% higher than that of pure PMMA nanofibres under sunlight irradiation for 5 h.

Material-specific properties applied to an environmental risk assessment of engineered nanomaterials – implications on grouping and read-across concepts

Engineered nanomaterials (ENMs) are intentionally designed in different nano-forms of the same parent material in order to meet application requirements. Different grouping and read-across concepts are proposed to streamline risk assessments by pooling nano-forms in one category. Environmental grouping concepts still are in their infancy and mainly focus on grouping by hazard categories. Complete risk assessments require data on environmental release and exposure not only for ENMs but also for their nano-forms. The key requirement is to identify and to distinguish the production volumes of the ENMs regarding nano-form-specific applications. The aim of our work was to evaluate whether such a grouping is possible with the available data and which influence it has on the environmental risk assessment of ENMs. A functionality-driven approach was applied to match the material-specific property (i.e. crystal form/morphology) with the functions employed in the applications. We demonstrate that for nano-TiO2, carbon nanotubes (CNTs), and nano-Al2O3 the total production volume can be allocated to specific nano-forms based on their functionalities. The differentiated assessments result in a variation of the predicted environmental concentrations for anatase vs. rutile nano-TiO2, single-wall vs. multi-wall CNTs and α- vs. γ-nano-Al2O3 by a factor of 2 to 13. Additionally, the nano-form-specific predicted no-effect concentrations for these ENMs were derived. The risk quotients for all nano-forms indicated no immediate risk in freshwaters. Our results suggest that grouping and read-across concepts should include both a nano-form release potential for estimating the environmental exposure and separately consider the nano-forms in environmental risk assessments.

Controlling Self-Assembly of Cellulose Nanocrystal to Synergistically Regulate (001) Reactive Facets and Hierarchical Pore Structure of Anatase Nano-TiO2 for High Photocatalytic Activity

As one of the most efficient and environmentally benign strategies to treat organic dye pollution, TiO2 photocatalytic technology has attracted increasing and wide interests in environmental governance, for which dominantly exposed (001) facets and high porosity are of great importance for catalytic performance. To date, however, how to synergistically regulate the dominant growth of (001) facets and the formation of hierarchical pore structures still remains challenging. Here, we report a limited growth strategy mediated by the self-assembly of cellulose nanocrystal (CNC) to prepare anatase TiO2 nanocatalyst with dominantly exposed (001) reactive facets. Notably, crystal growth in the confined space of layered CNC structures favors exposing (001) facets, and the easy removal of the soft biotemplate facilitates creating hierarchical pores. Furthermore, the (001) facet percentage, pore size, and porosity can be easily modulated by controlling the CNC concentration. After introducing an up-conversion quantu...

Preparation and photocatalytic performance of the rod-shaped Ni-NiO/TiO2 hollow composite structure based on metallization cellulose fibers and TBOT

The rod-shaped Ni-NiO/TiO2 hollow composite structure based on metallization cellulose fibers and Titanium butoxide (TBOT) via Sol-Gel method was fabricated to obtain a highly active rod-shaped hollow catalysts. The results showed that the high-heat treatment had no obvious influence on the hollow structure cavity size and the ideal surface roughness value of hollow structure was 6.385 μm. The XRD patterns revealed that the Ni and TiO2 particles that had been deposited on cellulose fibers had a crystallite size structure between 16.5 and 19.4 nm. The characteristic absorption peak at 1035 cm−1 assigned to Ti-O-C of anatase nano-TiO2 on hollow structure surface appeared. It is feasible to control the crystallite size and hollow cavity pore size via Sol-Gel method. The magnetic hollow structure shown here can be applied as catalysts and it can be completely natural subsidence within 5 min. Herein, the catalytic capacity of the rod-shaped Ni-NiO/TiO2 hollow composite structure for Cu (II) was found to be 5696 mg g−1.

TiO2 nanoparticles disrupt cell adhesion and the architecture of cytoskeletal networks of human osteoblast-like cells in a size dependent manner.

Human exposure to titanium dioxide nanoparticles (nano-TiO2 ) is increasing. An internal source of nano-TiO2 is represented by titanium-based orthopedic and dental implants can release nanoparticles (NPs) upon abrasion. Little is known about how the size of NPs influences their interaction with cytoskeletal protein networks and the functional/homeostatic consequences that might follow at the implant-bone interface with regard to osteoblasts. We investigated the effects of size of anatase nano-TiO2 on SaOS-2 human osteoblast-like cells exposed to clinically relevant concentrations (0.05, 0.5, 5 mg/L) of 5 and 40 nm spherical nano-TiO2 . Cell viability and proliferation, adhesion, spread and migration were assessed, as well as the orientation of actin and microtubule cytoskeletal networks. The phosphorylation of focal adhesion kinase (p-FAKY397 ) and the expression of vinculin in response to nano-TiO2 were also assessed. Treatment with nano-TiO2 disrupted the actin and microtubule cytoskeletal networks leading to morphological modifications of SaOS-2 cells. The phosphorylation of p-FAKY397 and the expression of vinculin were also modified depending on the particle size, which affected cell adhesion. Consequently, the cell migration was significantly impaired in the 5 nm-exposed cells compared to unexposed cells. The present work shows that the orientation of cytoskeletal networks and the focal adhesion proteins and subsequently the adhesion, spread and migration of SaOS-2 cells were affected by the selected nano-TiO2 in a size dependent manner. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2582-2593, 2018.

The size-dependent apoptotic effect of titanium dioxide nanoparticles on endothelial cells by the intracellular pathway.

Concerns over the health risk of the widely distributed, commonly used titanium dioxide nanoparticles (nano-TiO2 ) are increasing worldwide. Yet, up-to-now, our understanding in their potential effects on the cardiovascular system is very limited and the toxicological mechanisms are still unclear. In the present study, the CCK-8 assay was performed to determine the cytotoxicity of four sizes (10, 30, 50, and 100 nm) of anatase nano-TiO2 on human umbilical vein endothelial cells (HUVECs) in culture, and the flow cytometry was employed to investigate the potential of these nano-TiO2 to induce the apoptosis of HUVECs. The apoptotic pathway was also probed through the determination of the protein expression and activation of p53, Bax, Bcl-2, caspases-9, -7, -3, and PARP by western blot. The results showed that at the administrative levels (1, 5, 25 μg/mL), all the four sizes of nano-TiO2 could significantly inhibit the viability of HUVECs and elicit significant apoptosis in them, compared with the negative control (P < .05, P < .01). Moreover, the apoptotic rates of HUVECs were increased respectively with the elevating levels and decreasing sizes of the administrative nano-TiO2 , showing a clear dose- and size-dependent effect relationships. Interestingly, the increasing phosphorylation of p53, decreasing ratio of Bcl-2/Bax, and enhancing activation of the downstream proteins caspase-9, -7, -3, and PARP, were also observed with the decreasing sizes of the administrative nano-TiO2 in the western blot, indicating that the intracellular approach of apoptosis, the p53-caspase pathway, is the major way of the nano-TiO2 -mediated apoptosis in HUVECs in culture and that the size is an important parameter that may determine the potential of nano-TiO2 to induce cellular response. In conclusion, these results suggested that high levels of nano-TiO2 exposure may pose potential risks to human cardiovascular health by inducing cardiovascular EC apoptosis.