Ultraviolet absorption spectrum of laser-ablated titanium dioxide nanoparticles

The ultraviolet (UV) absorption spectra of titanium dioxide nanoparticles synthesized by laser ablation are studied. The band gap of the particles and the effect exerted on it by various factors, such as the laser radiation intensity during the synthesis of nanoparticles and the temperature of subsequent annealing of the particles in a furnace, are determined from the analysis of the spectra. The dependence of the peak positions in the UV spectra on the type of defects in the structure of the nanoparticles is discussed.     

Biosynthesis of titanium dioxide nanoparticles using bacterium Bacillus subtilis

The present study reports a low-cost, new material, eco-friendly and reproducible microbes Bacillus subtilis mediated biosynthesis of TiO₂ nanoparticles. Titanium dioxide nanoparticles synthesized from titanium as a precursor, using the bacterium, B. subtilis. The synthesized nanoparticles were characterized and confirmed as TiO₂ nanoparticles by using the UV spectroscopy, XRD, FTIR, AFM and SEM analysis. The morphological characteristics were found to be spherical, oval in shape, individual nanoparticles as well as a few aggregates having the size of 66–77 nm. The XRD shows the crystallographic plane of anatase of TiO₂ nanoparticles, indicating that nanoparticles structure dominantly correspond to anatase crystalline titanium dioxide.     

Silica and titanium dioxide nanoparticles cause pregnancy complications in mice

The increasing use of nanomaterials has raised concerns about their potential risks to human health. Recent studies have shown that nanoparticles can cross the placenta barrier in pregnant mice and cause neurotoxicity in their offspring, but a more detailed understanding of the effects of nanoparticles on pregnant animals remains elusive. Here, we show that silica and titanium dioxide nanoparticles with diameters of 70 nm and 35 nm, respectively, can cause pregnancy complications when injected intravenously into pregnant mice. The silica and titanium dioxide nanoparticles were found in the placenta, fetal liver and fetal brain. Mice treated with these nanoparticles had smaller uteri and smaller fetuses than untreated controls. Fullerene molecules and larger (300 and 1,000 nm) silica particles did not induce these complications. These detrimental effects are linked to structural and functional abnormalities in the placenta on the maternal side, and are abolished when the surfaces of the silica nanoparticles are modified with carboxyl and amine groups.     

Osseointegration evaluation of laser-deposited titanium dioxide nanoparticles on commercially pure titanium dental implants

The nanotechnology field plays an important role in the improvement of dental implant surfaces. However, the different techniques used to coat these implants with nanostructured materials can differently affect cells, biomolecules and even ions at the nano scale level. The aim of this study is to evaluate and compare the structural, biomechanical and histological characterization of nano titania films produced by either modified laser or dip coating techniques on commercially pure titanium implant fixtures. Grade II commercially pure titanium rectangular samples measuring 35?×?12?×?0.25?mm length, width and thickness, respectively were coated with titania films using a modified laser deposition technique as the experimental group, while the control group was dip-coated with titania film. The crystallinity, surface roughness, histological feature, microstructures and removal torque values were investigated and compared between the groups. Compared with dip coating technique, the modified laser technique provided a higher quality thin coating film, with improved surface roughness values. For in vivo examinations, forty coated screw-designed dental implants were inserted into the tibia of 20 white New Zealand rabbits’ bone. Biomechanical and histological evaluations were performed after 2 and 4 weeks of implantation. The histological findings showed a variation in the bone response around coated implants done with different coating techniques and different healing intervals. Modified laser-coated samples revealed a significant improvement in structure, surface roughness values, bone integration and bond strength at the bone-implant interface than dip-coated samples. Thus, this technique can be an alternative for coating titanium dental implants.     

Preparation, characterization and photocatalytic activities of holmium-doped titanium dioxide nanoparticles

The objective of the proposed work was focused to provide promising solid-phase materials that combine relatively inexpensive and high removal capacity of some radionuclides from low-level radioactive liquid waste (LLRLW). Four various zeolite minerals including natural clinoptilolite (NaNCl), natural chabazite (NaNCh), natural mordenite (NaNM) and synthetic mordenite (NaSM) were investigated. The effective key parameters on the sorption behavior of cesium (Cs-134) were investigated using batch equilibrium technique with respect to the waste solution pH, contacting time, potassium ion concentration, waste solution volume/sorbent weight ratio and Cs ion concentration. The obtained results revealed that natural chabazite (NaNCh) has the higher distribution coefficients and capacity towards Cs ion rather than the other investigated zeolite materials. Furthermore, novel impregnated zeolite material (ISM) was prepared by loading Calix [4] arene bis(-2,3 naphtho-crown-6) onto synthetic mordenite to combine the high removal uptake of the mordenite with the high selectivity of Calix [4] arene towards Cs radionuclide. Comparing the obtained results for both NaSM and the impregnated synthetic mordenite (ISM-25), it could be observed that the impregnation process leads to high improvement in the distribution coefficients of Cs⁺ ion (from 0.52 to 27.63 L/g). The final objective in all cases was aimed at determining feasible and economically reliable solution to the management of LLRLW specifically for the problems related to the low decontamination factor and the effective recovery of monovalent cesium ion.     

Preparation,characterization and photocatalytic activities of holmium-doped titanium dioxide nanoparticles

Holmium-doped TiO₂ nanoparticles with high photocatalytic activities were prepared by sol–gel method and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, and surface area measurement by nitrogen adsorption in this study. Experimental results indicated holmium doping could increase the surface area of TiO₂ nanoparticles, and inhibit the growth of crystalline size and the anatase-to-rutile phase transformation. The results of photodegrading methyl orange showed holmium doping improved the photocatalytic activity of TiO₂, and the reasons could be attributed to the synergetic effects of large surface areas, small crystallite size, lattice distortion and more charge imbalance of holmium-doped TiO₂. In our experiment, the optimal doped amount was 0.3 mol.% for the maximum photocatalytic degradation ratio when holmium-doped TiO₂ was calcined at 500 °C, and the optimal calcined temperature was 600 °C when the doped amount was 0.5 mol.%.     

Characterization of silver nanoparticles synthesized on titanium dioxide fine particles

Silver nanoparticles with a narrow size distribution were synthesized over the surface of two different commercial TiO(2) particles using a simple aqueous reduction method. The reducing agent used was NaBH(4); different molar ratios TiO(2):Ag were also used. The nanocomposites thus prepared were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), dynamic light scattering (DLS) and UV-visible (UV-vis) absorption spectroscopy; the antibacterial activity was assessed using the standard microdilution method, determining the minimum inhibitory concentration (MIC) according to the National Committee for Clinical Laboratory Standards. From the microscopy studies (TEM and STEM) we observed that the silver nanoparticles are homogeneously distributed over the surface of TiO(2) particles and that the TiO(2):Ag molar ratio plays an important role. We used three different TiO(2)Ag molar ratios and the size of the silver nanoparticles is 10, 20 and 80?nm, respectively. It was found that the antibacterial activity of the nanocomposites increases considerably comparing with separated silver nanoparticles and TiO(2) particles.     

Synthesis of titanium dioxide nanoparticles by reactive DC magnetron sputtering

Nanometer-sized titanium dioxide (TiO₂) particles were prepared on carbon substrates by reactive direct-current magnetron sputtering. By performing measurements with high resolution electron microscopes, the mean nanoparticle diameter and the coverage fraction of the substrate by the nanoparticles (NPs) were measured at 19 nm and 30%, respectively. Moreover, electron diffraction analysis showed that the TiO₂ NPs' crystalline structure on the carbon substrate was a mixture of anatase and rutile. Finally, we provided information on the TiO₂ initial growth stage: crystalline NPs were formed after deposition of amorphous nanoparticles on the substrate and heating.     

Dose dependent in vivo metabolic characteristics of titanium dioxide nanoparticles

Nanoparticle in vivo characteristics and interactions between nanoparticles and organisms are key components of nanotoxicology. 1H NMR was used to analyze rat urine metabolites exposed to TiO, nanopartcles by intratracheal instillation in low (0.8 mg/kg), medium (4 mg/kg) and high doses (20 mg/kg). Significant metabolite (Acetate, Valine, Dimethylamine, Taurine, Hippurate, and 2-Oxoglutarate) changes were only observed in the low dose group. These compensatory changes resolve within seven days, and the results of serum biochemical assays also implied no parenchymal damages in the liver or kidney. Rats exposed to medium and high dose nanoparticles had pulmonary inflammation because most of the instilled particles aggregated into larger sizes and accumulated in lung tissue. We conclude that low dose instillation of nano-TiO, can recoverably impact metabolic function because the scattered nanoparticles can migrate from the lung to liver or kidney, but particles in higher doses will aggregate and deposit in the lung without migration.     

Fabrication and characterization of superhydrophobic high opacity paper with titanium dioxide nanoparticles

A new type of paper with superhydrophobic surface was prepared by addition of modified nano-TiO₂ to cellulose pulp. Nano-TiO₂ powder was first dispersed with a high-speed homogenizer, followed by surface modification with the coupling agent, 3-(trimethoxysilyl) propyl methacrylate (MPS). The superhydrophobic and opaque paper was obtained by adding the modified nano-TiO₂ to plant fiber to change its characteristics from hydrophilic to hydrophobic. The effects of the initial content of the coupling agent MPS used, on the weight percentage of MPS attached on the surface of nano-TiO₂ were studied. The obtained paper was characterized by contact angle measurements and SEM. The results showed that the water contact angles for the modified paper ranged from 126.5 to 154.2°, and the sliding angle was <3°. Moreover, many well-dispersed nano-TiO₂ protuberances were observed on the surface of the paper, which further confirmed that the obtained paper was superhydrophobic on account of its nanostructure. Comparative optical studies performed on the paper handsheets revealed a much higher opacity for the sample with the MPS-modified-TiO₂ nanoparticles.     

Solution growth of KDP single crystals doped with titanium dioxide nanoparticles

Pure KDP single crystals and KDP crystals doped with TiO₂ nanocrystals were grown by the method of temperature reduction from aqueous solutions. Adsorption of the phosphate-ions on the surface of TiO₂ particles was studied by FTIR spectroscopy. It was shown that the nanoparticles with adsorbed H₂PO₄^– and (H₂PO₄)₂^2–anions were incorporated predominantly into the positively charged face (1 0 1) of the pyramidal sector of KDP. High-resolution X-ray three-crystal diffractometry (TCD) investigation of the as grown samples of KDP + TiO₂ revealed the presence of the turns of the growth layer “stacks” up to 3 arcsec in the growth sectors {1 0 0} and {1 0 1}. The observed thickness of these “stacks” was of the order of 20–30 μm. For KDP + TiO₂ crystals there was found a relative change of the crystal lattice parameter (Δd/d) caused by incorporation of TiO₂ nanoparticles into the boundaries of the growth layers. This gave rise to the formation of a semicoherent binding on the interface between the captured TiO₂ and the matrix. No essential influence of the nanoparticles on the laser damage threshold of KDP with 10⁻⁵ wt.% of TiO₂ was established.     

Surface modification of elongated one-dimensional titanium dioxide structures with ferromagnetic nanoparticles

Nanostructured TiO₂ in the form of elongated one-dimensional structures having a highly ordered layered morphology, with cobalt-containing agglomerates on their surface, has been prepared by hydrothermal treatment of CoTiO₃ powder in the presence of chitosan, a bioactive natural polymer. The synthesis products have been characterized by scanning electron microscopy, transmission electron microscopy, IR spectroscopy, X-ray diffraction, elemental analysis, and magnetic measurements. The structures have been shown to be up to several microns in length, and their typical width ranges from 100 to 400 nm. The one-dimensional structures retain high thermal stability at calcination temperatures of up to 800°C. After vacuum heat treatment at 600°C and above, the nanostructured material possesses anomalously high ferromagnetic characteristics.     

Synthesis of functional diamond-like carbon nanocomposite films containing titanium dioxide nanoparticles

Synthesis of diamond-like carbon (DLC) films with UV-induced-hydrophilicity function was studied by inductively-coupled plasma (ICP) chemical vapor deposition. Titanium tetraisopropoxide (TTIP) and oxygen gases were employed as the precursors to deposit diamond-like nanocomposite films containing titanium dioxide (TiO₂) nanoparticles. X-ray diffraction and high-resolution transmission electron microscopy revealed that TiO₂ nanocrystallites were formed in the DLC films when oxygen concentration was higher than TTIP concentration during deposition. The DLC nanocomposite film was hydrophobic without ultraviolet (UV) irradiation, and became highly hydrophilic under UV irradiation, exhibiting the self-cleaning effect. A very broad peak centered at 1580 cm^− 1 was observed in the Raman spectra confirming the formation of DLC films. The hardness of the film was about 8 GPa with a stress of 3 GPa. ICP was essential in forming the photocatalytic TiO₂ nanoparticles in the DLC matrix.     

Electrospun titanium dioxide nanofibers containing hydroxyapatite and silver nanoparticles as future implant materials

In this study, a good combination consisting of electrospun titanium dioxide (TiO₂) nanofibers incorporated with high purity hydroxyapatite (HAp) nanoparticles (NPs) and antimicrobial silver NPs is introduced for hard tissue engineering applications. The synthesized nanofibers were characterized by various state of art techniques like; SEM, XRD, TEM, TEM EDS and XPS analyses. SEM results confirmed well oriented nanofibers and good dispersion of HAp and silver NPs, respectively. XRD results demonstrated well crystalline feature of three components used for electrospinning. Silver NPs were having a diameter in range of 5–8 nm indicated by TEM analysis. Moreover, TEM EDS analysis demonstrated the presence of each component with good dispersion over TiO₂ nanofiber. The surface analyses of nanofibers were investigated by XPS which indicated the presence of silver NPs on the surfaces of nanofibers. The obtained nanofibers were checked for antimicrobial activity by using two model organisms E. coli and S. aureus. Subsequently, antimicrobial tests have indicated that the prepared nanofibers do posses high bactericidal effect. Accordingly, these results strongly recommend the use of obtained nanofiber mats as future implant materials.     

Influence of natural organic matter on the aggregation and deposition of titanium dioxide nanoparticles

The aggregation kinetics of TiO(2) nanoparticles was studied in the absence and presence of Suwanee River humic acid (SRHA) in either NaCl or CaCl(2) electrolytes. The CCC[Ca(2+)]/CCC[Na(+)] ratios were found to yield a proportionality fraction of z(-7.2) (in the absence of SRHA) and z(-5.6) (in the presence of SRHA), near the theoretical prediction of z(-6), where z is the cation's valence. SRHA drastically increased the stability of TiO(2) nanoparticles under most conditions, due to the combined effect of increased electrostatic and steric repulsions. Deposition rates of TiO(2) nanoparticles onto a silica surface were quantitatively measured using a quartz crystal microbalance with dissipation (QCM-D) over a broad range of solution (pH and ionic strength, IS) conditions, and the effects of the SRHA on particle deposition behavior were evaluated. In general, zeta potential can be used to predict the interaction energies between particles or particles and surfaces, and from there an inference can be made as to the potential for aggregation and deposition. The presence of SRHA significantly hinders TiO(2) deposition onto silica surfaces via steric repulsion in addition to repulsive electrostatics even under high ionic strength, which has important implications for the mobility of these nanoparticles.     

Cytotoxicity of titanium dioxide nanoparticles differs in four liver cells from human and rat

Titanium dioxide (TiO₂) nanoparticles (NPs) are the important nanoscale components of composites. Although TiO₂ NPs and their related nanocomposites have been widely used in industrial and medical applications, the adverse effects of TiO₂ nanomaterials have not been well studied. Here, we investigated the cytotoxicity of TiO₂ NPs in vitro using four liver cell lines: human hepatocellular carcinoma cell line (SMMC-7721), human liver cell line (HL-7702), rat hepatocarcinoma cell line (CBRH-7919) and rat liver cell line (BRL-3A). We checked cell viability, cell morphology, and the levels of reactive oxygen species (ROS) and glutathione (GSH) after TiO₂ exposure at varying concentrations (0.1–100 μg/mL) and different exposure periods of time (12–48 h). Compared to the NP-free control, all four cell lines exposed to TiO₂ NPs showed cytotoxicity in a dosage-dependent and time-dependent manner, which was associated with the changes of cell viability and cell morphology, increased intercellular ROS levels, and decreased intracellular GSH levels. Further, we observed that carcinomatous liver cells and human liver cells exhibited more tolerance to TiO₂ NPs exposure for 24 h, compared to normal liver cells and rat liver cells, respectively. The results indicate that the in vitro cytotoxicity induced by NPs should be assessed with great caution before the use of nanocomposites and that there is a need to standardize the cytotoxicity testing procedure of nanoscale components in composites when using different cell lines.     

Antibacterial properties of poly(quaternary ammonium) modified gold and titanium dioxide nanoparticles

We report excellent antibacterial effect induced by amine-functionalized gold and titanium dioxide nanoparticles without external excitations. The idea originates from the excellent antibacterial property of quaternary ammonium salts. The effects of poly(quaternary ammonium) and polyacrylate sodium functional groups as nanoparticle surfactants are compared to show that poly(quaternary ammonium) functional groups are the main cause of the induced antibacterial effect. 99.999% of E. coli can be destructed in 10 minutes by simply mixing bacteria with nanoparticle dispersions. The effect of nanoparticle concentrations on the antibacterial property is evaluated. Time required to significantly suppress bacteria growth is studied. The result indicates that the excellent antibacterial property can be introduced to any nanomaterials by using poly(quaternary ammonium) functional groups as surfactants. The engineered nanoparticles can find enormous applications such as self-cleaning surfaces, waste water treatment, Lab-on-a-Chip devices and many more.     

Internalization, translocation and biotransformation of silica-coated titanium dioxide nanoparticles in neural stem cells

Nanotechnology has gained massive applications in the fields of biology and pharmacology. Recently, more research attention has been paid to explore the interaction between nanoparticles (NPs) and cells, in particular, the entry of NPs into cells. Herein, we focus on the internalization of the FITC-labeled silica-coated titania NPs (FITC-TiO2@SiO2 NPs) in neural stem cells (NSCs) and their subsequent translocation. Various microscopic techniques, such as confocal-laser-scanning microscopy (CFLSM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to track the time-dependent pathway of NPs in cells. It was found that NPs traversed cell membrane and localized around the cell nucleus. Most NPs congregated in lysosomes and were transformed by lysosomes after 48 h co-incubation.     

Molecular mechanism of hippocampal apoptosis of mice following exposure to titanium dioxide nanoparticles

Previous studies demonstrate that the exposure to titanium dioxide nanoparticles (TiO(2) NPs) damages the central nervous system of mice; however, very little is known about the effects of TiO(2) NPs on hippocampal apoptosis or its molecular mechanism. The present study investigated the molecular mechanism associated with hippocampal apoptosis in mice induced by intragastric administration of TiO(2) NPs for consecutive 60 days. Our findings indicate that TiO(2) NPs accumulate in the mouse hippocampus, and this accumulation, in turn, led to hippocampal apoptosis and impairment in spatial recognition memory in mice. In addition, TiO(2) NPs significantly activated caspase-3 and -9, inhibited Bcl-2, and promoted the levels of Bax and cytochrome c. Furthermore, TiO(2) NPs induced accumulation of reactive oxygen species in the mouse hippocampus. These findings suggest that TiO(2) NP-induced apoptosis in the mouse hippocampus may result from an intrinsic pathway, and workers and consumers should take great caution when handling nanomaterials.