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Figure. (C) schematic of the HA/TNT/CNT nanocomposite tablet and ball in the reciprocating wear test; (C1–C5) schematics of different asperities and CNT distributions in different samples: HA, HA/TNT, HA/TNT/CNT-1.0, HA/TNT/CNT-1.5, and HA/TNT/CNT-2.0. • Synthesize of HA/TNT/CNT nanocomposite with different CNT contents. • Micro/Nano mechanical properties investigation of HA/TNT/CNT nanocomposite. • Structural and morphological analysis of HA/TNT/CNT nanocomposite. In this study, hydroxyapatite/titanium nanotube/carbon nanotube (HA/TNT/CNT) nanocomposites with different CNT contents were fabricated using a combination of hydrothermal and sol–gel methods. The nanocomposite powders were pressed at 350 MPa using the cold isostatic pressing technique and sintered at 1050 °C in a tube furnace in the presence of Ar gas. The nano/micromechanical properties, biocompatibility, and tribological characteristics of HA-based composites (with versatile mass ratios of CNT: 1.0, 1.5, and 2.0 wt%) were investigated. According to hardness-test results, the HA/TNT/CNT (2.0 wt% CNTs) composite exhibited the highest surface hardness (235.9 HV) among the samples. Wear-resistance tests were performed under different normal loadings. HA/TNT/CNT with higher CNT content exhibited a lower wear rate than the other samples. Nanoindentation tests were performed, and the nanohardness and elastic modulus of the HA were 62.41 and 1.821 GPa, respectively. These values were increased to approximately 98.7 and 5.3 GPa, respectively, for HA/TNT/CNT-2.0 (after the addition of TNTs and CNTs). The inclusion of 2.0 wt% CNTs in the HA/TNT composite reduced the wear debris volume by ∼ 66% owing to the enhanced modulus of elasticity and hardness. Moreover, in-vitro biocompatibility tests revealed that HA/TNT/CNT-2.0 had no cytotoxicity. [ABSTRACT FROM AUTHOR]

The main disadvantage of the implants is the associated infections. Therefore, in the long term, the possibility of improving the antibacterial capacity of different types of implants (dental, orthopedic) is being researched. The severity of the problem lies in the increasing bacterial resistance and finding appropriate alternative treatments for infectious diseases, which is an important research field nowadays. The purpose of this review is to draw a parallel between different studies analyzing the antibacterial activity and mechanism of silver nanoparticles (NP Ag) deposited on the titanium nanotubes (NTT), as well as the analysis of the NP Ag toxicity. This review also provides an overview of the synthesis and characterization of TiO2-derived nanotubes (NT). Thus, the analysis aims to present the existing knowledge to better understand the NP Ag implants benefits and their antibacterial activity. [ABSTRACT FROM AUTHOR]

A one-step process combining the photocatalytic degradation of radionuclide complexes and the adsorption of liberated radionuclides on titanium dioxide nanotubes was developed and tested for the purification of aqueous waste produced from chemical decontamination of nuclear power plant circuit components. Among the tested forms of TiO2, only nanotubes exhibit both high photocatalytic activity and sorption ability, which support their application in a one-step purification process. The obtained results indicate that the photocatalytic degradation of complexes followed by the sorption of the radionuclides onto TiO2 nanotubes offers a promising route for treating spent decontamination fluids. [ABSTRACT FROM AUTHOR]

Several methods have been invented to desalinate saltwater for industrial or domestic uses, but still, they need to be improved to reduce the cost and environmental impacts. In this study, a desalination cell is inserted in the middle of photoelectrocatalytic cells to separate ions, and drag them into the electrolytes. The driving force, in this method, is ultraviolet illumination, exciting coated titanium nanotubes on the anode electrode, and then produces electron/hole pairs. Holes degrade organic matters, and electrons are transferred by an external circuit to the cathode chamber. Ultrafiltration membrane (UF) is used for the first time as a separator barrier between chambers in this photo redox desalination method. The performance of photo electro desalination cell (UF-PEDC) in different independent parameters like salt content, pH, resistivity, and illumination density is investigated. The UF-PEDC desalinates 42.54% of saltwater with the total dissolved solids (TDS) of 78.57 g/l and also degrades 96.46% of methylene blue as an organic matter after 70 h. This experiment shows that UF-PEDC can operate longer, more efficient, and with a higher TDS removal rate than microbial desalination cells and is a suitable choice to desalinate hypersaline streams produced in reverse osmosis methods. • UF-PEDC was used for the first time to desalinate hypersaline water • In UFPEDC, saltwater desalination, photocatalytic degradation of MB, and current production happen, simultaneously • Desalination rate and its TDS removal efficiency is more than MDCs • It works better in a hypersaline condition so that it can be used as a pretreatment in the RO process [ABSTRACT FROM AUTHOR]

This investigation describes the formation of crystalline nanotubes of titanium oxide on the surface of a Ti-6Al-4V alloy and its biological evaluation. The formation of nanotubes was performed by the anodic oxidation technique with a constant work potential of 60 V but with different anodizing times of 10, 20, 30, 40, 50, and 60 min used to evaluate their effects on the characteristics of the nanotubes and their biological activity. A mixture of ethylene glycol, water, and ammonium fluoride (NH4F) was used as the electrolytic fluid. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to determine the morphology and crystalline nature of the nanotubes, showing a well-defined matrix of nanotubes of titanium oxide with a crystalline structure and a diameter in the range of 52.5 ± 5.13 to 95 ± 11.92 nm. In contrast, the XRD patterns showed an increase of defined peaks that directly correlated with treatment times. Moreover, in vitro assays using an innovative cell culture device demonstrated that the inner diameter of the nanotubes directly correlated with cell proliferation. [ABSTRACT FROM AUTHOR]

In recent years, nano-reinforcing technologies for cementitious materials have attracted considerable interest as a viable solution for compensating the poor cracking resistance of these materials. In this study, for the first time, titanium nanotubes (TNTs) were incorporated in cement pastes and their effect on the mechanical properties, microstructure, and early-age hydration kinetics was investigated. Experimental results showed that both compressive (~12%) and flexural strength (~23%) were enhanced with the addition of 0.5 wt.% of TNTs relative to plain cement paste at 28 days of curing. Moreover, it was found that, while TNTs accelerated the hydration kinetics of the pure cement clinker phase (C3S) in the early age of the reaction (within 24 h), there was no significant effect from adding TNTs on the hydration of ordinary Portland cement. TNTs appeared to compress the microstructure by filling the cement paste pore of sizes ranging from 10 to 100 nm. Furthermore, it could be clearly observed that the TNTs bridged the microcracks of cement paste. These results suggested that TNTs could be a great potential candidate since nano-reinforcing agents complement the shortcomings of cementitious materials. [ABSTRACT FROM AUTHOR]

Anodic oxidation is an easy and cheap surface treatment to form nanostructures on the surface of titanium items for improving the interaction between metallic implants and the biological environment. The long-term success of the devices is related to their stability. In this work, titanium nanotubes were formed on a dental screw, made of titanium CP2, through an anodization process using an “organic” solution based on ethylene glycol containing ammonium fluoride and water. Then, the electrochemical stability in the Hank’s solution of these “organic” nanotubes has been investigated for 15 days and compared to that of titanium nanotubes on a similar type of sample grown in an inorganic solution, containing phosphoric and hydrofluoridric acids. Morphological and crystallographic analysis were performed by using scanning electron microscopy (SEM) and X-Ray diffractometry (XRD) tests. Electrochemical measurements were carried out to study the stability of the nanotubes when are in contact with the biological environment. The morphological measurements revealed long nanotubes, small diameters, smooth side walls, and a high density of “organic” nanotubes if compared to the “inorganic” ones. XRD analysis demonstrated the presence of rutile form. An appreciable electrochemical stability has been revealed by Electrochemical Impedance Spectroscopy (EIS) analysis, suggesting that the “organic” nanotubes are more suitable for biomedical devices. [ABSTRACT FROM AUTHOR]

Background: Minocycline has been widely used in central nervous system disease. However, the effect of minocycline on the repairing of nerve fibers around dental implants had not been previously investigated. The aim of the present study was to evaluate the possibility of using minocycline for the repairing of nerve fibers around dental implants by investigating the effect of minocycline on the proliferation of Schwann cells and secretion of neurotrophic factors nerve growth factor and glial cell line-derived neurotrophic factor in vitro.Methods: TiO2 nanotubes were fabricated on the surface of pure titanium via anodization at the voltage of 20, 30, 40 and 50 V. The nanotubes structure were characterized by scanning electron microscopy and examined with an optical contact angle. Then drug loading capability and release behavior were detected in vitro. The TiO2 nanotubes loaded with different concentration of minocycline were used to produce conditioned media with which to treat the Schwann cells. A cell counting kit-8 assay and cell viability were both selected to study the proliferative effect of the specimens on Schwann cell. Reverse transcription-quantitative PCR and western blot analyses were used to detect the related gene/protein expression of Schwann cells.Results: The results showed that the diameter of TiO2 nanotubes at different voltage varied from 100 to 200 nm. The results of optical contact angle and releasing profile showed the nanotubes fabricated at the voltage of 30 V met the needs of the carrier of minocycline. In addition, the TiO2 nanotubes loaded with the concentration of 20 μg/mL minocycline increased Schwann cells proliferation and secretion of neurotrophic factors in vitro.Conclusions: The results suggested that the surface functionalization of TiO2 nanotubes with minocycline was a promising candidate biomaterial for the peripheral nerve regeneration around dental implants and has potential to be applied in improving the osseoperception of dental implant. [ABSTRACT FROM AUTHOR]

One-dimensional nanotubes have attracted enormous attention due to their specific structure and excellent performance since the carbon nanotube was prepared. In this study, the open-ended SrTiO3 nanotubes (STNTs) have been fabricated for the first time via an isomorphic conversion strategy using the protonated titanate nanotubes (HTNTs) as the precursor and template under the hydrothermal treatment. The as-prepared STNTs consist of uniform and continuous multilayers, having inner and outer diameters about 8.0 and 13 nm. The STNT formation involves the exchange of Sr2+ ions with H+ ions in HTNTs and then in situ growth of cubic SrTiO3 crystals by the templating of HTNT frameworks. It is found that the diffusion process of Sr2+ ions plays a critical role in controlling the nanotube morphology of SrTiO3 crystals. In addition, the SrTiO3 nanotubes exhibit high photocatalytic activity for the Cr(VI) reduction, which can reduce nearly 100% Cr(VI) within 6 h under simulated sunlight irradiation. The current strategy may be broadly applicable for fabricating the nanotubes from raw materials without 2D layered nanostructure.ᅟ [ABSTRACT FROM AUTHOR]

The amorphous to anatase transformation of anodized nanotubular titania surfaces has been studied by x-ray diffraction and transmission electron microscopy (TEM). A more rapid heat treatment for conversion of amorphous to crystalline anatase favorable for orthopedic implant applications was demonstrated. Nanotube titania surfaces were fabricated by electrochemical anodization of Ti6Al4V in an electrolyte containing 0.2 wt% NH4F, 60% ethylene glycol and 40% deionized water. The resulting surfaces were systematically heat treated in air with isochronal and isothermal experiments to study the temperature and time dependent transformation respectively. Energy dispersive spectroscopy shows that the anatase phase transformation of TiO2 in the as-anodized amorphous nanotube layer can be achieved in as little as 5 min at 350 °C in contrast to reports of higher temperature and much longer time. Crystallinity analysis at different temperatures and times yield transformation rate coefficients and activation energy for crystalline anatase coalescence. TEM confirms the (101) TiO2 presence within the nanotubes. These results confirm that for applications where amorphous titania nanotube surfaces are converted to crystalline anatase, a 5 min production flow-through heating process could be used instead of a 3 h batch process, reducing time, cost, and complexity. [ABSTRACT FROM AUTHOR]

We fabricate photo-anodes by transferring anodic TiO2 nanotube membranes in tube-top-down configuration on FTO glass, and use them for constructing frontside illuminated dye-sensitized solar cells. Prior to solar cell construction, the tube-based photo-anodes are crystallized at different temperatures (400–800 °C), and the effects of tube electron transport properties on the photovoltaic performance of the solar cells are investigated. We show that improved solar cell efficiencies (up to ca. 8.0%) can be reached by high-temperature treatment of the tube membranes. Consistent with electron transport time measurements, remarkably enhanced electron mobility is enabled when tube membranes are crystallized at 600 °C. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V-based nanotubes were prepared on a Ti-6Al-4V surface by anodic oxidation on 10 V, 20 V, and 30 V samples. The 10 V, 20 V, and 30 V samples and a control smooth Ti-6Al-4V sample were evaluated in terms of their chemical composition, diameter distribution, and cellular response. The surfaces of the 10 V, 20 V, and 30 V samples consisted of nanotubes of a relatively wide range of diameters that increased with the voltage. Saos-2 cells had a similar initial adhesion on all nanotube samples to the control Ti-6Al-4V sample, but it was lower than on glass. On day 3, the highest concentrations of both vinculin and talin measured by enzyme-linked immunosorbent assay and intensity of immunofluorescence staining were on 30 V nanotubes. On the other hand, the highest concentrations of ALP, type I collagen, and osteopontin were found on 10 V and 20 V samples. The final cellular densities on 10 V, 20 V, and 30 V samples were higher than on glass. Therefore, the controlled anodization of Ti-6Al-4V seems to be a useful tool for preparing nanostructured materials with desirable biological properties.

To optimize mesenchymal stem cell differentiation and antibacterial properties of titanium (Ti), nano-sized zinc oxide (ZnO) particles with tunable concentrations were incorporated into TiO2 nanotubes (TNTs) using a facile hydrothermal strategy. It is revealed here for the first time that the TNTs incorporated with ZnO nanoparticles exhibited better biocompatibility compared with pure Ti samples (controls) and that the amount of ZnO (tailored by the concentration of Zn(NO3)2 in the precursor) introduced into TNTs played a crucial role on their osteogenic properties. Not only was the alkaline phosphatase activity improved to about 13.8 U/g protein, but the osterix, collagen-I, and osteocalcin gene expressions was improved from mesenchymal stem cells compared to controls. To further explore the mechanism of TNTs decorated with ZnO on cell functions, a response surface mathematical model was used to optimize the concentration of ZnO incorporation into the Ti nanotubes for stem cell differentiation and antibacterial properties for the first time. Both experimental and modeling results confirmed (R (2) values of 0.8873-0.9138 and 0.9596-0.9941, respectively) that Ti incorporated with appropriate concentrations (with an initial concentration of Zn(NO3)2 at 0.015 M) of ZnO can provide exceptional osteogenic properties for stem cell differentiation in bone cells with strong antibacterial effects, properties important for improving dental and orthopedic implant efficacy.