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Development of bone fixation devices with excellent corrosion resistance, antibacterial ability, and osteogenic activity is critical for promoting fracture healing. In this study, Zn-incorporated nanopore (NP) layers were prepared on the NiTi alloy through anodization and hydrothermal treatment. Results show that Zn can be evenly incorporated into the NP layers in the form of ZnTiO3. The Zn-incorporated samples exhibit good corrosion resistance and significantly reduce Ni2+ release. Meanwhile, the samples can continuously release Zn2+, which is responsible for excellent long-term antibacterial ability. Furthermore, the synergetic effect of Zn2+ release and nanoporous structure of the NP layers endues the NiTi alloy excellent osteogenic activity, as verified by upregulated alkaline phosphatase activity, secretion of type I collagen, and extracellular matrix mineralization. Therefore, Zn-incorporated Ni-Ti-O NP layers have great potential as biomedical coatings of NiTi-based implant materials.

Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer, but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer and antibacterial properties to inhibit cancer/bacteria invasion. The present work aims at endowing the NiTi alloy with anticancer and antibacterial abilities by surface modification. Ni–Ti–O nanoporous layers with different thicknesses were prepared on NiTi by anodization, and biological experiments were conducted to evaluate the effects on gram-positive Staphylococcus aureus, human lung epithelial cancer cells (A549), as well as human endothelial cells (EA. hy926). The nanoporous layer with a thickness of 10.1 μm inhibits growth of cancer cells and kill bacteria but shows little adverse effects on normal cells. Such selectivity is related to the larger amount of Ni ions leached from the sample in the acidic microenvironment of cancer cells in comparison with normal cells. The Ni–Ti–O nanoporous layers are promising as coatings on NiTi stents to prevent re-obstruction after surgery.

A multi-functional composite coating was fabricated on magnesium (Mg) AZ31 alloy through micro-arc oxidation (MAO) combined with self-assembly technology. Polyethyleneimine (PEI) as a medium was assembled on MAO coating based on the chemical bonding and electrostatic interactions. Adhered PEI successfully mediates the self-assembly of functional silver nanoparticles (Ag NPs) with a formation of Ag NPs/PEI/MAO (APM) composite coating. The morphology and microstructure of as-prepared APM coating were characterized by using of different technologies (e.g. scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy). Its corrosion behavior in simulated body fluid and the corresponding antibacterial performance against Staphylococcus aureus (S. aureus) were also investigated. The potentiodynamic polarization results showed that the corrosion current density of APM coated AZ31 decreased more than three orders of magnitude in comparison with that of uncoated AZ31, indicating an enhanced anticorrosive ability. Electrochemical impedance spectroscopy results further revealed that the improvement of corrosion resistance was attributed to a synergistic effect of Ag NPs/PEI and MAO. The hydrogen evolution tests confirmed that APM coating provided AZ31 an excellent corrosion protection during a relatively long term. And the antibacterial research showed that APM coated AZ31 had a great antibacterial activity. This study presents a promising approach to fabricate a multi-functional composite coating on Mg alloy, which improves the anticorrosive performance of the substrate and endows it an antibacterial activity to meet a better demand in the applications.

Titanium (Ti) has been extensively used in medical devices owing to their low density, high strength, excellent corrosion resistance, and biocompatibility. However, thrombus formation and bacterial infections are still challenges for their application in specific clinical cases. Hence, we have developed a simple, efficient, and stable strategy that endow Ti with anticoagulant and antibacterial properties through chemical bonding and electrostatic bonding. A large number of hydroxyl groups were produced on the surface of Ti by annealing at 500 °C. Then, heparin was immobilized on annealed surface with chemical bonding and chitosan was captured in an electrostatically bound manner by simply soaking in solution. The results indicated that the surface-functionalized Ti exhibited excellent anticoagulant properties by a reduction in platelet adhesion and prolonged blood clotting time. Furthermore, the modified Ti also showed antibacterial properties against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

Magnesium (Mg) and its alloys are considered as promising implant materials due to their biodegradability. However, high degradation rate cannot well match tissue repair process and may result in severe cytotoxicity. In addition, post-surgery infection may also raise safety concerns. In the present work, solid diffusion zinc was adopted to construct a barrier coating on the surface of AZ31B Mg alloy. The results show the coating is composed of MgZn and Mg2Zn11 intermetallics, which possesses good corrosion resistance, antibacterial ability, and cytocompatibility. The alloy after 8 h of the treatment shows the highest comprehensive performance thus is promising as biomedical coating of Mg alloy.

Favorable osteogenic activity and antibacterial ability are highly desired for hard tissue repair and replacement materials. However, as a typical implant material, nearly equiatomic nickel‑titanium (NiTi) alloy exhibits poor osteogenic and antibacterial capacities despite its good biocompatibility and unique mechanical properties. In this work, nickel‑titanium‑oxygen (Ni-Ti-O) nanopores (NPs) coatings incorporated with magnesium (NP-Mg) are fabricated on the NiTi alloy by anodization and hydrothermal treatment (HT). The results show the amount of loaded Mg can be regulated by the NPs length (1.8 and 10.4 μm) and the hydrothermal duration (1 and 5 h). In addition, the surface morphology of the coatings transform to nanosheets after HT for 1 h and to NPs with small diameter after HT for 5 h. Bone marrow mesenchymal stem cells (BMSCs) cultured on NP-Mg-coated NiTi alloy show better proliferation and osteogenic differentiation than that of pristine and as-anodized specimens. Antibacterial experiments show although HT reduces Ni ion release and increase corrosion resistance, the NP-Mg coatings yet maintain potent antibacterial activity especially against adherent bacteria. The NPs coating with thickness of 10.4 μm and HT for 5 h shows favorable osteogenic activity, antibacterial ability, little Ni ion release, and good corrosion resistance thus is a promising candidate to functionalize the surface of the NiTi alloy for orthopedic applications.

Nonthermal plasma (NTP)-enhanced CO catalytic oxidation over CuOx@γ-Al2O3 was investigated in a coaxial dielectric barrier discharge reactor at ambient temperature under dry and humid conditions. T...

This work provides an environmental friendly route to fabricate ternary silver/silver oxide/zinc oxide (Ag/Ag2O/ZnO) photocatalyst with assistance of bovine serum albumin (BSA). The structural analysis indicates that Ag/Ag2O/ZnO photocatalyst is a 3D-flowerlike architecture. Nanoparticles composed of Ag and Ag2O in diameter about 40 nm attach on the surfaces of ZnO “petals” and form a heterojunction structure with ZnO. The ultraviolet-visible (UV–vis) spectra and photoluminescence (PL) spectra show that the obtained Ag/Ag2O/ZnO nanocomposite displays an enhanced visible-light absorption and a decreased fluorescence emission compared to that of ZnO. The photocatalytic performance of Ag/Ag2O/ZnO nanocomposite was evaluated by photocatalytic degradation of methylene blue (MB) under simulated visible light irradiation. The results indicate that Ag/Ag2O/ZnO nanocomposite exhibits better photocatalytic activity than that of single- and two-component photocatalysts including ZnO, Ag2O, TiO2 and Ag/ZnO. Ag/Ag2O/ZnO nanocomposite also has a good recycling stability and still maintains a high degradation efficiency (85%) after four recycles. The improved photocatalytic activity is credited to the synergistic effect of Ag, Ag2O and ZnO nanophases in the Ag/Ag2O/ZnO heterojunction, which results in an effective charge separation and a low recombination of photo-induced electron-hole pairs.

The present work reports on the hydrothermal synthesis of nanosheets on biomedical NiTi alloy in pure water. The results show rhombohedral NiTiO3 nanosheets with thickness of 6 nm can be grown at 200 °C. Hydrothermal treatment enhances the corrosion resistance of the NiTi alloy. 30 min of the treatment significantly reduces Ni ion release, while prolonged hydrothermal time results in increased Ni ion release because of the growth of the nanosheets with large specific surface area. Excitingly, the nanosheets can well support cell growth, which suggests the release amount can be well tolerated. Good corrosion resistance and cytocompatibility combined with large specific surface area render the nanosheets promising as safe and efficient drug carriers of the biomedical NiTi alloy.

Nearly equiatomic nickel–titanium (NiTi) alloy is an ideal implant biomaterial because of its shape memory effect, superelasticity, low elastic modulus as well as other desirable properties. However, it is prone to infection because of its poor antibacterial ability. The present work incorporated Cu into Ni–Ti–O nanopores (NP–Cu) anodically grown on the NiTi alloy to enhance its antibacterial ability, which was realized through electrodeposition. Our results show that incorporation of Cu (0.78 at%–2.37 at%) has little influence on the NP diameter, length and morphology. The release level of Cu ions is in line with loadage which may be responsible for the improved antibacterial ability of the NiTi alloy to combat possible bacterial infection in vivo. Meanwhile, the NP–Cu shows better cytocompatibility and even can promote proliferation of bone marrow mesenchymal stem cells (BMSCs), up-regulate collagen secretion and extracellular matrix mineralization when compared with Cu-free sample. Better antibacterial ability and cytocompatibility of the NP–Cu render them to be promising when serving as NiTi implant coatings.

We describe a strategy to fabricate a hydrogel-based microvascular construct by direct writing alginate bioink inside the viscous pre-polymer of hydrogels, which acts as a support bath. As the print needle translates through the polymers, the extruded alginate instantaneously forms calcium alginate hydrogel (Ca-Alg) templates deposited within the bath. This phase change allows the formed templates to be anchored within the pre-polymers, while maintaining their structure. After the printing process, the pre-polymers are solidified to form a mechanically robust hydrogel. Finally, a hydrogel construct with embedded microchannels is generated by liquefying and removing the Ca-Alg templates. Using this method, not only the alginate ink alone can be directly printed within the engineered constructs, but also the size and shape of the formed microchannels are controllable. Furthermore, a confluent endothelial layer for the generation of vascular networks can be constructed by adhering and proliferating endothelial cells on the channel linings. This strategy demonstrates a promising technique for rapid construction of in vitro vasculatures, which would provide a versatile platform for a wide array of applications such as tissue engineering, organ-on-a-chip and drug screening.

Impressive progress has been made on the development of magnesium alloys (Mg) implants in cardiovascular and orthopedic applications due to their good mechanical strength and biodegradable. In this paper, heparin and carboxymethyl chitosan were immobilized on alkali-treated Mg to improve the hemocompatibility and antibacterial activities. Electrochemical tests revealed that the surface modified Mg obviously improved the corrosion resistance. Additionally, the surface-functionalized Mg exhibited excellent antithrombotic and antibacterial activities.

Copper, a frequently used additive of implant materials, can alter macrophage phenotype thus directing the fate of the implants. Exosomes, secreted by mammalian cells, can target to recipient cells and mediate their functions. However, whether exosomes derived from macrophages upon copper ion stimulation can modulate angiogenesis, a key index for implant osseointegration, is still unclear. Herein, the influence of copper ions on macrophage-derived exosome secretion, ingestion behavior by endothelial cells, and angiogenic-induction ability is investigated. The results show copper ions (0–100 μM) have little influence on the secretion of macrophage-derived exosomes. Endothelial cells can uptake the exosomes from all the groups in a time-dependent manner. The exosomes have little influence on endothelial adhesion and proliferation, but can upregulate angiogenic ability of endothelial cells in vitro and in vivo, which may be related to trafficking of integrin β1. The results provide insight into the effect of copper ions on immunomodulatory mechanism of macrophages, which is important for implant design from the perspective of material compositions.

Stent implantation has become one of the most widely used methods for the treatment of cardiovascular diseases. However, endothelial dysfunction and abnormal inflammatory response following implantation may lead to delayed re-endothelialization, resulting in vascular restenosis and stent thrombus. To address the concerns, we constructed nanospindles composed of TiO2 and Ti4Ni2O through hydrothermal treatment of amorphous Ni-Ti-O nanopores anodically grown on NiTi alloy. The results show the treatment can significantly improve hydrophilicity and reduce Ni ion release, essentially independent of hydrothermal duration. The nanospindle surfaces not only promote the expression of endothelial functionality but also activate macrophages to induce a favorable immune response, downregulate pro-inflammatory M1 markers and upregulate pro-healing M2 markers. Moreover, nitric oxide (NO) synthesis, VEGF secretion, and migration of endothelial cells are enhanced after cultured in macrophage conditioned medium. The nanospindles thus are promising as vascular stent coatings to promote re-endothelization.

The growth of newly formed particles with diameters from ~ 10 nm to a larger size was investigated in Beijing's urban atmosphere on 10–23 December 2011, 12–27 April 2012 and through June–August 2014. The maximum geometric median diameter (Dpgmax) of newly formed particles in 11/27 new particle formation (NPF) events through June–August exceeded 75 nm, and the grown new particles may contribute to the population of cloud condensation nuclei. In contrast, no apparent growth in new particles with Dpgmax

Osseointegration is crucial for early fixation as well as for long-term implantation success, hence numerous efforts have been made to tune the surface topography or chemical composition of biomedical implants to improve osseointegration. In this work, various nanostructures, including nanoflocs, nanobundles, nanorods, and nanoleaves, were introduced to the surface of silicon (Si)-incorporated microporous structure to form Si-incorporated micro-nano hierarchical structures on titanium (Ti)-based implants. The osseointegration of the implants were systemically assessed in vivo and in vitro. The in vitro evaluations showed that the nanostructures promoted the protein adsorption, thus modulating the early cellular responses, including the attachment and spreading of osteoblasts and human endothelial cells (HUVECs), and subsequent cell proliferation and differentiation. Furthermore, compared with the single microporous structure, the nanostructures located over the microporous structure protected the Si ions from quick release and allowed the long-term sustained Si-ions release, which further contributed to the proliferation and differentiation of osteoblasts and vascular endothelial growth factor (VEGF) secretion as well as the tube formation of HUVECs. Collectively, the favorable nano-surface structures, especially the nanoleaves structure, and the constant Si-ion release together led to robust osteogenic and angiogenic activities. More importantly, in vivo micro-CT evaluation and histological observations further verified that the Si-incorporated micro-nano hierarchical implant with nanoleaves structure could efficiently promote new bone formation, thus indicating it was an attractive candidate as a next-generation bone-implant material.

The degradation of toluene in dielectric barrier discharge (DBD) reactor packed with zeolites or MnOx/zeolites was investigated. The supported catalysts were prepared by loading 3 wt% of manganese on different zeolites (MCM-41, ZSM-5 and 13X) and were characterized in detail using N2 adsorption, XRD, TEM, H2-TPR and XPS analysis technology. Compared to the non-thermal plasma (NTP) alone system, the toluene degradation was improved significantly in NTP-MnOx/zeolites system. The highest toluene conversion of 99.4%, the CO2 selectivity of 73%, the carbon balance of 99.5% can be achieved in DBD reactor packed with MnOx/MCM-41. Both XRD and TEM results confirm that the manganese oxides were dispersed more uniformly on MnOx/MCM-41 than on MnOx/ZSM-5 or MnOx/13X. H2-TPR and XPS results suggest that manganese oxides on MnOx/MCM-41 are MnO2 and Mn2O3, while those on MnOx/ZSM-5 or MnOx/13X are MnO2 and MnO. These results indicate that the structures of zeolites play a significant role in the dispersion and oxidation state of manganese oxides, then affecting the activity of catalyst for toluene removal in plasma-catalysis system.

The present work investigated the effects of annealing on corrosion behavior, Ni2+ release, cytocompatibility, and antibacterial ability of nickel-titanium-oxygen (Ni-Ti-O) nanopores (NPs) anodically grown on nearly equiatomic NiTi alloy, aiming at optimizing annealing process to yield favorable comprehensive performance. The morphology and crystal structure of the NPs were characterized by scanning electron microscopy and X-ray diffraction respectively. It was found that when the annealing temperature was

Magnesium alloys have been recognized as promising implant materials because of their biodegradability. However, rapid degradation due to electrochemical corrosion compromises their cytocompatibility and mechanical integrity. In the present work, a porous ZrO2 ceramic coating was constructed on the surface of AZ31B magnesium alloy (ZrO2-AZ31B) to improve its corrosion resistance. The corrosion resistance of the coating was evaluated in simulated body fluid solution by electrochemical techniques. Higher open circuit potential, impedance and polarization resistance of ZrO2-AZ31B indicate it has a better corrosion resistance than that of AZ31B substrate in simulated body fluid solution. The results suggest that fabricating a ZrO2 ceramic coating on magnesium alloys is an effective method to decrease the degradation rate of magnesium alloys thereby better matching clinical requirements.

The influence of electrolyte pH on anodic growth of Ni-Ti-O nanopores on NiTi alloy was investigated. Through manipulating HCl, NaCl, and NaOH concentrations in the electrolyte composed of 95 vol% ethylene glycol, 5 vol% H2O, and 0.15 M Cl−, the electrolyte pH was varied from 0.82 to 13.5. Although the pH has little influence on surface morphology and composition of the nanopores, it can significantly impact their growth rate. Initially, increase of the pH decreases the growth rate from 13.8 nm/s at pH = 0.82 to 5.7 nm/s at pH = 7.0. However, when the pH exceeds 7.0, its value increases with the pH and reaches up to 15.8 nm/s at pH = 13.5. The knowledge gained from this study should be valuable in the anodization of other valve metals and their alloys.

Fabrication of SiC nanoarrays is highly recommended owing to the fact that it is the key to push forward them being applied in optoelectronic devices. Nevertheless, majority of the reported works involving the growth of SiC low-dimensional nanostructures were often carried out under the harsh conditions (e.g., high temperatures and/or high pressures), which were teemed as the key obstacle for the accomplishment of their controllable and repeatable growth. In the current work, we reported the controllable and repeatable large-scale fabrication (up to centimeter×centimeter of width × length in area) of well-aligned, free-standing and transparent 4H-SiC nanohole arrays via anodic oxidation of SiC wafers at room temperature and atmospheric pressure conditions. It was discovered that the cycle period of the pulsed voltage played a crucial role in the formation of highly uniform nanohole arrays. In the meantime, the diameters, wall thickness and depth of the nanoholes could be modulated through the customization of the cycle times. Additionally, a possible mechanism was proposed for the formation of nanohole arrays.

A multifaceted coating for hard tissue implants, with favorable osteogenesis, angiogenesis , and osteoimmunomodulation abilities, would be of great value since it could improve osseointegration and alleviate prosthesis loosening. However, to date there are few coatings that fully satisfy these criteria. Herein we describe a microporous TiO 2 coating decorated with hydroxyapatite (HA) nanoparticles that is generated by micro-arc oxidation of pure titanium (Ti) and followed annealing. By altering the annealing temperature, it is possible to simultaneously tune the coating's physical (morphology and wettability) and chemical (composites and crystallinity) properties. A coating produced with micro-arc oxidization (MAO) with an annealing temperature of 650 °C (MAO-650) exhibits numerous favorable physicochemical properties , such as hybrid micro-nano morphology, superhydrophilicity, and highly crystalline HA nanoparticles. In vitro experiments reveal that the MAO-650 coating not only supports proliferation and differentiation of both osteoblasts and endothelial cells, but also inhibits the inflammatory response of macrophages and enables a favorable osteoimmunomodulation to facilitate osteo/angio-genesis. In vivo evaluation mirrors these results, and shows that the MAO-650 coating results in ameliorative osseointegration when compared with the pristine MAO coating. These data highlight the profound effect of surface physicochemical properties on the regulation of osteo/angio-genesis and osteoimmunomodulation in the enhancement of osseointegration.

We report on a reliable and cost-effective method (alkali corrosion) to construct nanosheet layers on nearly equiatomic nickel-titanium (NiTi) alloy, which only needs to immerse it in1−15 M NaOH solution at low temperature (4–80 ℃). The layers are mainly composed of TiO2, Na4TiO4, and Ni(OH)2, and Ni content increases with NaOH concentration. The layers exhibit potent antibacterial ability and can promote endothelial spreading and proliferation, although the corrosion resistance is slightly decreased due to significantly increased specific surface area. Good corrosion resistance, antibacterial ability, and cytocompatibility render the nanosheet layers promising as biomedical coatings of the NiTi alloy.

Zn-doped ZrO2/TiO2 porous coatings (Zn-ZrO2/TiO2) were prepared on the surface of titanium alloy (Ti6Al4V) by a hybrid approach of magnetron sputtering and micro-arc oxidation (MAO). The microstructures, phase constituents and elemental states of the coating were investigated by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the Zn-ZrO2/TiO2 coatings are porous and its thickness is approximately 13μm. The major phases in the oxidation coating are tetragonal ZrO2 (t-ZrO2), cubic ZrO2 (c-ZrO2) and rutile TiO2. XPS result reveals that Zn exists as ZnO in the Zn-ZrO2/TiO2 coatings. The biological experiments indicate that Zn-ZrO2/TiO2 coatings exhibit not only excellent antibacterial property against Gram-positive Staphylococcus aureus (S. aureus), but also favorable cytocompatibility. In addition, the corrosion resistance of the coating is also appreciably improved in the simulated body fluids (SBF), which can ensure better biocompatibility in body fluids.

We have synthesized sodium tris(alkoxy)benzoates in which one of the three alkyl chains branches further into three C18H37 chains. These AB5 hyperbranched minidendrons melt directly into a body-centred cubic (BCC) mesophase formed by spherical “micelles”. In contrast, their non-branched counterparts display various mesophases before they turn into BCC upon heating. This agrees with the predictions from a numerical geometric model that relates the shape of the molecular wedge to the type of mesophase they adopt. The spheres were found to shrink in volume upon heating and expand upon cooling, as molecules, in some cases nearly half of them, are ejected and reintegrated in the spheres. The ejection of dendrons is caused by their lateral thermal expansion. The BCC appears to be the ultimate mesophase for the extremely divergent wedges such as the hyperbranched minidendrons. In dendrons with chains of unequal length, the sphere size is fixed by the shorter chains, the longer ones back-folding or interdigitating to effectively widen the wedge. This new understanding of their assembly will help in designing new dendrons, e.g. for better encapsulation of guest molecules.

Objective The purpose of this work was to explore the enhancement effect of zinc doped mesoporous silica nanoparticles (Zn-MSNs), which could form micromechanical interlocking with resin matrix and sustainably release Zn2+, on the mechanical and antibacterial properties of the dental resin composites. Methods Zn-MSNs were prepared by a sol–gel method, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption/desorption. The mechanical properties of the dental composites reinforced by Zn-MSNs were measured by a universal mechanical testing machine. Antibacterial activities of dental composites were evaluated by both qualitative and quantitative analysis using Streptococcus mutans (S. mutans). The cytotoxicity of the Zn-MSNs filled dental composites was investigated by osteoblasts (OBs). Results The synthesized Zn-MSNs possessed good monodispersity with an average particle size of about 138 nm. The mechanical properties of the composites gradually increased with the increase of the content of Zn-MSNs. The flexural strength, flexural modulus, compressive strength and micro-hardness of the composites containing 15 wt% Zn-MSNs were 31.21%, 50.47%, 53.83% and 26.79% higher than the samples with no Zn-MSNs, respectively. The antibacterial performance was significantly improved by the addition of Zn-MSNs and the antibacterial rate of the composite with 15 wt% of Zn-MSNs reached 100%. Cytotoxicity tests revealed that all the composites were biocompatible during OBs incubation. Significance The prepared Zn-MSNs can effectively improve the mechanical and antibacterial properties of the dental resin composites.

In this study, an oxide layer on Ti-based implants is fabricated by using a high current anodization (HCA) technique in the nitrate electrolyte. This layer is composed of micro-pits and nano-porous arrays in the honeycomb structure. The results show that both the roughness and the layer thickness are related to the reaction time, whereas the size of nano-pores has little to do with the anodization duration. Compared to the nano-tubular arrays constructed by the conventional anodization, this nano-porous layer shows significantly improved mechanical stability. Furthermore, the in vitro assay of osteoblasts shows that cells behaviors on this surface can be modulated by the topology of this special layer. A suitable hierarchical structure composed of micro-pits and nano-porous structure can significantly stimulate osteoblasts attachment, activity, spreading and ALP function. Therefore, this hierarchical surface layer may provide a promising approach, which endows the Ti-based implants with better stability and osseointegration.

The electrochemical stability of Ni-Ti-O nanoporous layers anodically grown on the equiatomic NiTi alloy is assessed by immersion in deionized water and phosphate buffered saline and the influence of immersion on the corrosion behavior and biological properties is studied systematically. The morphology, chemical composition, and microstructure of the layers exhibit no obvious change even after immersion for 60 days in the two media and the corrosion resistance, antibacterial ability, and cytocompatibility are retained as well. These findings indicate the Ni–Ti–O nanoporous layers are stable and have large potential as coatings on NiTi biomedical implants.

Magnesium (Mg) has been considered as the next-generation orthopedic implant material due to its biodegradability, but high degradation rate and severe cytotoxicity hinder its clinical application. Preparing micro-arc oxidation (MAO)/octacalcium phosphate (OCP) composite coating is considered as an ideal approach to solve the problems. In this work, nanostructured OCP coatings with variable structures were prepared facilely on MAO coated Mg by chemical deposition (CD) in a simple trace PO43- ion contained Ca(NO3)2 solution. The results show that nanostructured OCP grows and covers the MAO coating completely after CD. The morphology and thickness of OCP coating can be regulated by varying deposition time. The thinnest OCP coating with a fine structure is observed after 0.5 h of deposition, which shows the best cytocompatibility. Extending deposition time roughens the surface structure and thickens the coatings. The thickest OCP coating with a coarse structure can be obtained after 2 h of deposition, which shows the best corrosion resistance and mineralization. These results clearly indicate the functionality of the OCP coating can be easily tailored only by varying deposition time to meet different clinical requirements.

The numerous advantages of hydrogel make it possible to apply as dressing. However, it is challenging in designing hydrogels with desired antibacterial activity and enhanced mechanical properties at the same time. Herein, a graphene oxide/rose bengal/polyvinyl alcohol hybrid hydrogel (β-GO/RB/PVA HD) is prepared by freezing and thawing a mixed polyvinyl alcohol (PVA) solution of rose bengal (RB) immobilized with chitosan microspheres (CM) and a modified graphene oxide network (β-GO). The mechanical properties and light-triggered antibacterial activity of hydrogel are systematically evaluated. The β-GO inorganic network interpenetrate into the PVA porous structure, which significantly improves the mechanical properties of hydrogel. The hyperthermia generated by β-GO under 808 nm light irradiation combined with reactive oxygen species (ROS) produced by RB under 550 nm light irradiation give rise to excellent antibacterial activity requiring irradiation for only 10 min as demonstrated by our experiments conducted in vitro and in vivo. Meanwhile, β-GO/RB/PVA HD exhibits outstanding biocompatibility and water-absorbing capacity. More importantly, the hybrid hydrogel can significantly accelerate bacteria-accompanied wound healing. The results demonstrated that the hybrid hydrogel could be a promising wound dressing for preventing bacterial infection.

Well-ordered, one-dimensional silver-doped anatase TiO2 nanowire (AgNW) arrays have been prepared through a hydrothermal growth process on the sputtering-deposited AgTi layers. Electron microscope analyses reveal that the as-synthesized AgNW arrays exhibit a single crystalline phase with highly uniform morphologies, diameters ranging from 85 to 95 nm, and lengths of about 11 μm. Silver is found to be doped into TiO2 nanowire evenly and mainly exists in the zerovalent state. The AgNW arrays show excellent efficient antibacterial activity against Escherichia coli (E. coli), and all of the bacteria can be killed within 1 h. Additionally, the AgNW arrays can still kill E. coli after immersion for 60 days, suggesting the long-term antibacterial property. The technique reported here is environmental friendly for formation of silver-containing nanostructure without using any toxic organic solvents.

This study aims to simulate depositions of size-segregated particles in human airway in Beijing, China during seasons when fine particulate matter concentrations are high (December 2011 and April 2012). Particle size distributions (5.6–560 nm, electrical mobility diameter) near a major road in Beijing were measured by the TSI Fast Mobility Particle Sizer (FMPS). The information of size distributions provided by FMPS was applied in the Multiple-Path Particle Dosimetry model (MPPD) to quantify number and mass depositions of particles in human airway including extrathoracic (ET), tracheobronchial (TB), and pulmonary (PUL) regions of exposed Chinese in Beijing. Our results show that under ambient conditions, particle number concentration (NC) deposition in PUL is the highest in the three major regions of human airway. The total particle NC deposition in human airway in winter is higher than that in spring, especially for ultrafine particles (1.8 times higher) while particle mass concentration (MC) deposition is higher in spring. Although particle MC in clean days are much lower than that in heavily polluted days, total particle NC deposition in human airway in clean days is comparable to that in heavily polluted days. NC deposition for nucleation mode particles (10–20 nm, aerodynamic diameter) in clean days is higher than that in heavily polluted days. MC deposition for accumulation mode particles (100–641 nm, aerodynamic diameter) in heavily polluted days is much higher than that in clean days, while that of nucleation mode is negligible. The temporal variation shows that the arithmetic mean and the median values of particle NC and MC depositions in the evening are both the highest, followed by morning and noon, and it is most likely due to increased contribution from traffic emissions.

Titanium (Ti) is widely used in the field of hard tissue implant materials due to its desirable mechanical properties and biocompatibility, but its osteogenic activity is relatively poor, hindering its clinical applications. In this work, Na-Ti-O nanostructured film was prepared on Ti surface by anodization in 2 M NaOH electrolyte at different applied voltages. The results show that uniform film can be formed when the voltage is between 15 and 25 V. Compared with untreated Ti, the anodized samples can promote osteoblast spreading, proliferation, and osteogenic differentiation. These results indicate Na-Ti-O nanostructured film is promising to functionalize Ti-based materials for dental and orthopedic applications.

Nearly equiatomic nickel-titanium (NiTi) alloys are used in many biomedical applications due to their favorable properties, but in some cases, the surface properties such as corrosion resistance and biological characteristics may be inadequate, especially for clinical applications. Electrochemical self-assembly is an emerging surface modification method for valve metals and their alloys and the ordered oxide nanostructures produced by this method not only increase the corrosion resistance, but also regulate the cell behavior. Herein, recent advances pertaining to self-assembled anodization of NiTi alloys and biomedical applications are described. In particular, the influence of the preparation parameters on the morphology, microstructure, composition, corrosion behavior, Ni ion release, and biological response of self-assembled Ni–Ti–O nanotubes and nanopores are comprehensively analyzed and discussed.

Ni-Ti-O nanotubes (NTs) anodically grown on nearly equiatomic NiTi alloy are promising in biomedical field, but mechanical polishing pretreatment of the substrate usually results in severe pitting. The present work proposes to use electropolishing (EP) as pretreatment of anodization of the NiTi alloy to eliminate the side effect of mechanical polishing. Scanning electron microscopy was used to observe the morphology of the samples. Potentiodynamic polarization test was carried out to evaluate the corrosion behavior. Biological experiments were performed to assay their cytocomaptibility and antibacterial ability. Our results show pitting can be completely avoided after substrate EP pretreatment, yielding a macro smooth surface, while micro ordered nanotubular structure is well preserved. EP pretreatment enhances the corrosion resistance and antibacterial ability of the NiTi alloy when compared with that of mechanically polished sample, and all the samples show no appreciable cytotoxicity, clearly indicating EP is a promising pretreatment for fabricating Ni-Ti-O NTs on the NiTi alloy for biomedical applications.

In this study, we provide a photocurable chitosan bioink (CHI-MA), which can be used for the digital light processing (DLP) technology. The CHI-MA precursors were facilely synthesized by grafting chitosan molecular chains with methacryloyl groups. We investigated the effect of parameters, including the concentration and substitution degree (DS) of CHI-MA, on the rheology and the photocuring of bioinks and the mechanical property of photo-crosslinked gels. Using the CHI-MA with a high DS (33.6 %), the curing time to print a 150 μm thick hydrogel layer can be controlled within a reasonable short time period. Additionally, the cytotoxicity test shows that both the photocuring process and the photo-crosslinked hydrogels exhibit an excellent biocompatibility. Through the DLP printing, the CHI-MA bioink can be processed into complex 3D hydrogel structures with high-resolution, high-fidelity and good biocompatibility. It indicates that the photocurable CHI-MA would be a good bioink suitable for the DLP printing.

Clinical application of magnesium (Mg) in bone reconstruction has been hindered owing to its high degradation rate in physiological environment. Surface modification by the strategy combining micro-arc oxidation (MAO) and hydrothermal treatment (HT) to prepare a composite coating (MAO-HT) and improve its corrosion resistance has been proved an effective method. In this work, Mg was micro-arc oxidized in electrolyte with different Na3PO4 contents, and subsequently hydrothermally treated in Ca(NO3)2 solution. The results show that hydroxyapatite (HA) can be fabricated on MAO coating after HT for 4 h. The HA shows nano-flake morphology when P content in the MAO coating is low (12.1 at%), while nano-particle morphology is observed when the P content is high (20.0 at %). Electrochemical tests reveal an improved corrosion resistance of MAO-HT coatings than corresponding MAO coatings. In vitro biological tests indicate that MAO-HT coatings are more favorable for MG63 cells proliferation than MAO coatings. Especially, Nano-flake HA/MAO composite coating shows the highest corrosion resistance and cytocomatibility thus is promising as biomedical coatings of Mg.

The present work reports on the hydrothermal conversion of Ni-Ti-O nanopores anodically grown on NiTi alloy into nanospindles and their cytocompatibility. The results show the amorphous nanopores can transform to anatase nanospindles with length concentrated at 70–110 nm and diameter at 16–24 nm upon hydrothermal treatment at 200 °C in pure water for 2 h. The nanospindles also can promote proliferation of bone marrow mesenchymal stem cells when compared with that of nanopores and bare NiTi alloy thus are promising as biomedical coatings of NiTi alloy.

Coating materials applied for intraosseous implants must be optimized to stimulate osseointegration. Osseointegration is a temporal and spatial physiological process that not only requires interactions between osteogenesis and angiogenesis but also necessitates a favorable immune microenvironment. It is now well-documented that hierarchical nano-micro surface structures promote the long-term stability of implants, the interactions between nano-micro structure and the immune response are largely unknown. Here, we report the effects of microporous titanium (Ti) surfaces coated with nano-hydroxyapatite (HA) produced by micro-arc oxidation and steam-hydrothermal treatment (SHT) on multiple cell behavior and osseointegration. By altering the processing time of SHT it was possible to shift HA structures from nano-particles to nano-rods on the microporous Ti surfaces. Ti surfaces coated with HA nano-particles were found to modulate the inflammatory response resulting in an osteoimmune microenvironment more favorable for osteo-/angio-genesis, most likely via the activation of certain key signaling pathways (TGF-β, OPG/RANKL, and VEGF). By contrast, Ti surfaces coated with nano-rod shaped HA particles had a negative impact on osteo-/angio-genesis and osteoimmunomodulation. In vivo results further demonstrated that Ti implant surfaces decorated with HA nano-particles can stimulate new bone formation and osseointegration with enhanced interaction between osteocytes and implant surfaces. This study demonstrated that Ti implants with micro-surfaces coated with nano-particle shaped HA have a positive impact on osseointegration. Statement of Significance Osteo-/angio-genesis are of importance during osteointegration of the implants. Recent advances unravel that immune response of macrophages and its manipulated osteoimmunomodulation also exerts a pivotal role to determine the fate of the implant. Surface nano-micro modification has evidenced to be efficient to influence osteogenesis, however, little is known links nano-microstructured surface to immune response, as well the osteoimmunomodulation. This study demonstrates that the nano-particles decorated micro-surface, compared with the nano-rods decorated micro-surface enables osteogenesis and angiogenesis concurrently that has not been investigated previously. This study also unravels that the immune response of macrophages can be manipulated by the nano-micro surface, especially the nano-dimension matters, leading to a differential effect on osteointegration. The additional knowledge obtained from this study may provide foundation and reference for future design of the coating materials for implantable materials.

Implant-related infection is one of the most common and serious complications associated with biomedical implantation. To prevent bacterial adhesion, a series of porous TiO2 coatings with different concentrations of silver (designated as M0, M1, M2 and M3) were prepared on pure titanium substrates by a duplex-treatment technique combining magnetron sputtering with micro-arc oxidation. All coatings are porous with pore size less than 5 μm and the concentrations of silver in the M0, M1, M2 and M3 are 0, 0.95, 1.36 and 1.93 wt.%, respectively. Silver is found to be distributed throughout the thickness of the coatings by scanning electron microscopy. The release of silver from the TiO2 coatings was confirmed by an inductively-coupled plasma mass spectroscopy. The antibacterial effects of these coatings were tested against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli), and the cytotoxicity was evaluated using the mouse pre-osteoblast cells. The results indicate that the antibacterial activities of TiO2 coatings are greatly improved due to the incorporation of silver. No cytotoxic effect is found for the M1 surfaces from the observation of pre-osteoblast cell by MTT assay and fluorescence microscopy. Although the M2 and M3 coatings appeared to be toxic for pre-osteoblast cells after 1 day in culture, the cell viability on M2 and M3 surfaces was greatly raised after culturing for 2 days. Our results suggested that the TiO2 coatings incorporated with an optimum amount of silver can possess excellent antibacterial activities without cytotoxic effect, which has promising applications in biomedical devices.

In the present work, for the first time, we report the growth of hierarchical assemblies of Si 3 N 4 nanostructures via catalyst-assisted pyrolysis of a polymeric precursor on the Si substrates. The synthesized products were characterized by using field emission scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. It is found that the size of the catalytic droplet plays a critical role on the formation of hierarchical assemblies of Si 3 N 4 nanostructures rather than common single nanowire. A mechanism based on the Vapor–Liquid–Solid (VLS) process was proposed for the assembly of hierarchical Si 3 N 4 nanostructures.

Antibacterial TiO 2 coatings with different concentrations of Cu (Cu–TiO 2 ) were prepared by micro-arc oxidation (MAO) on pre-sputtered CuTi films. The effect of Cu concentrations in CuTi films on the MAO process was investigated. The Cu–TiO 2 coatings were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Cu–TiO 2 coatings was evaluated via potentiodynamic polarization method. The antibacterial properties were assessed by two methods: spread plate method and fluorescence staining. The experimental results demonstrate that the coatings are porous and consist of anatase phase, rutile phase and unoxidized titanium. The CuTi films are almost completely oxidized and the thickness of all MAO coatings is about 5–10 μm. Cu mainly exists as CuO in the TiO 2 coatings. The Cu–TiO 2 coatings exhibit excellent antibacterial activities, and the antibacterial rate gradually rise with the increase in Cu concentration in the MAO coatings. The corrosion resistance of MAO coatings is also improved slightly.

Sn4+-doped titanium dioxide photocatalytic films were synthesized on 304 stainless steel (SS) by a duplex treatment. The SS substrates were alloyed with titanium (Ti) through cathodic-arc ion plating followed by a microarc oxidation (MAO) treatment in different electrolytes. Field-emission scanning electron microscopy, x-ray diffraction, and energy dispersive spectroscopy were used to characterize the films surface morphology, crystalline phase, and composition, respectively. Photocatalytic activity was measured using an UV-Vis spectrophotometer. It was found that the films with a porous structure are mainly composed of TiO2, which exists in an anatase and rutile state. Furthermore, small quantities of SnO2 have been found in the Sn4+-doped titanium dioxide films. The fraction of anatase varies with the MAO time and electrolytes, whereas the pore size remains the similar with the same MAO current intensity and density and the surface roughness increases slightly with increasing MAO time. It was also found that the photocatalytic activity of the Sn4+-doped porous film improved, and the film synthesized with a shorter MAO time in a lower Na2SnO3-containing electrolyte is superior to the films with longer MAO times and higher Na2SnO3 concentrations.

Plasma surface copper and nickel alloying was applied to Ti6Al4V alloy. The effects of treatment temperatures on the microstructures were investigated by scanning electron microscope (SEM). The chemical composition and phase constituents of the alloyed layer were analyzed using glow discharge spectrum (GDS) and X-ray diffraction (XRD). The results show that the alloyed layer prepared at 850 °C with about 7 μm in thickness is bonded strongly to the Ti6Al4V substrate and consists of unbound Ti, Ti 2 Ni, TiNi, Cu 0.81 Ni 0.19 and CuTi. The results indicate that the treated samples exhibit excellent antibacterial properties within 12 h. The wear resistance of titanium alloy is also improved.

ZrN/Zr-N/Zr coatings were deposited on H13 steel by close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. The effect of two main parameters such as OEM and bias voltage for the CFUBMSIP process on the microstructure, mechanical properties and impact fatigue behavior of the coatings was investigated. The results indicate that with OEM increasing from 55% to 65% the surface particles size of the coatings increases while it remains almost similar when the bias voltage changes from 60 to 75 V. An aggregation of the particles occurs on the coatings surface with further increasing the OEM and bias voltage to 75% and 90 V, respectively. The coatings show a columnar grain structure and are mainly composed of two phases of ZrN and Zr. The coating hardness decreases with OEM value increasing and both the coating hardness and modulus go up with bias voltage. The coating deposited under OEM of 65% and bias voltage of 75 V shows the best impact fatigue property.

Infection associated with titanium implants remains the most common serious complication after surgery. In this work, Cu-doped antibacterial TiO2 coating was synthesized by micro-arc oxidation of titanium in an electrolyte bearing Cu nanoparticles. Surface morphology and structure of the coating were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicated that Cu nanoparticles were not only distributed on the surface and inside the pores but also embedded in the coating. Cu mainly exists in the Cu2+ state in the TiO2 coating. The Cu-doped coating exhibited excellent antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

We report on the influence of stirring of electrolyte (glycerol[Formula: see text] H2O [Formula: see text] NaCl) on anodic growth of Ni-Ti-O nanopores (NPs) on nearly equiatomic NiTi alloy at different applied voltages. The results show that anodization is a diffusion-controlled process. The stirring has little influence on the NP diameter, but shortens its length. High stirring speed of electrolyte yields high Ni content in the NPs, which is promising in electrocatalysis, biosensor, supercapacitor, and other related fields.