Titanium and its alloys have been widely used over the past 3 decades as implants for healing bone defects. Nevertheless, the bioinert property of titanium alloy limits its clinical application and surface modification method is frequently performed to improve the biological and chemical properties. Recently, the delivery of microRNA with osteogenesis capability has been recognized as a promising tool to enhance bone regeneration of implants. Here, we developed a biodegradable coating to modify the titanium surface in order to enhance osteogenic bioactivity. The previous developed nanocapsules were used as the building blocks, and then a bioactive titanium coating was designed to entrap the miR-29b nanocapsules. This coating was not only favorable for cell adhesion and growth but also provided sufficient microRNA transfection efficacy and osteoinductive potential, resulting in a significant enhancement of bone regeneration on the surface of bioinert titanium alloy.Keywords: bone regeneration; miR-29b; nanocapsules; osteogenic bioactivity; titanium

•Ag- and Sr-substituted HA was prepared by hydrothermal method.•Ag- and Sr-substituted HA coating was deposited on dopamine functionalized titanium.•Ag-substituted HA biofilm showed a remarkable antibacterial activity.•Sr could offset the side effects of Ag.Infection in primary total joint prostheses is attracting considerable attention. In this study, silver (Ag) was incorporated into hydroxyapatite (HA) using a hydrothermal method in order to improve its antimicrobial properties. Strontium (Sr) was added as a second binary element to improve the biocompatibility. The substituted HA samples were fixed on titanium (Ti) substrates by dopamine-assisted immobilization in order to evaluate their antibacterial and biological properties. The results showed that Ag and Sr were successfully incorporated into HA without affecting their crystallinity. Further, the antibacterial tests showed that all the Ag-substituted samples had good anti-bacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Despite their good antibacterial ability, the Ag-substituted samples showed evidence of cytotoxicity on MG63 cells, characterized by low cell density and poor spreadability. The addition of Sr to the Ag-substituted samples considerably reduced the cytotoxicity of Ag. Although the viability of the cells grown on the surfaces of co-substituted HA was not as high as that of the cells grown on the HA surfaces, it is believed that excellent antibacterial properties and good biological activity can be achieved by balancing the dosage of Sr and Ag.

•The film of a mixture of gentamicin sulphate (GS) and chitosan is fabricated.•Physical adsorption and cycling loading is effective for GS loading.•Chitosan layer can adjust the loading efficiency and the release kinetics.•The antibacterial activity is due to the synergistic effects of GS and chitosan.Bacterial infections have been identified as the main cause of orthopaedic implant failure. Owing to their high antibiotic delivery efficiency, titania nanotubes loaded with antibiotics constitute one of the most promising strategies for suppressing bacterial infections. However, it is difficult to control the drug-release behaviour of such nanotubes. Although sealing the nanotubes with a polymer solution provides sustained release effects to a certain extent, it inevitably influences their initial antibacterial activity. This study reports on the controlled release of gentamicin sulphate (GS) from titania nanotube surfaces whereby their initial antibacterial activity remains unaffected. Titania nanotubes were fabricated via electrochemical anodization and loaded with GS through physical adsorption. Experimental results showed that this loading method is feasible and efficient. The GS-loaded titania nanotubes were further covered by a thin film comprising a mixture of GS and chitosan (GSCH). The release kinetics confirmed that the drug release could be controlled by this thin film. Moreover, such a film was shown to not only inhibit initial bacterial adherence owing to its strong antibacterial properties but also enhance cell viability. Thus, GS-loaded titania nanotubes coated with GSCH have considerable potential as biomaterials for preventing initial release and peri-implant infection in the field of orthopaedics.

Magnesium (Mg) and strontium (Sr) have been widely used in the field of implanted devices because of their excellent bioactivity. However, the local high ion concentration caused by the implant affects the growth of hydroxyapatite (Ca10(PO4)6(OH)2, HA), which is the main inorganic component of bone and teeth. Many studies have investigated the effect of Mg2+ and Sr2+ on the growth of HA, but no systematic research has been conducted to compare these two ions in terms of the growth of HA. In this study, the substitution of a series of Sr- and Mg-substituted HA was conducted through a conventional hydrothermal method. Comprehensive characterization techniques, including X-ray diffraction, inductive coupled plasma, field emission scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, thermo gravimetric-differential scanning calorimetry, and Fourier transform infrared spectroscopy, were used to examine the effects of Sr2+ and Mg2+ on the phase, morphology, crystallinity, chemical composition, thermal stability, and lattice parameters of HA. The results indicated that Mg ions partially substituted for calcium (Ca) ions in the apatite structure, thus decreasing the lattice parameters, partially adsorbing on the apatite surface that formed the amorphous phase, and inhibiting the crystal growth. By contrast, Sr ions fully substituted for Ca ions and increased the lattice parameters. Both Mg and Sr ions affected the morphology of HA. Crystallinity decreased with the addition of Mg ions (transition from the crystal to amorphous phase was between 30% and 40% Mg), but it was not affected by Sr ions. Thermostability decreased with the addition of Mg (a total weight loss from 8.06 wt% for 10% Mg to 25.81 wt% for 50% Mg), but it had no significant changes in the Sr-substituted samples.

•MicroRNA (miRNA)/dopamine-modified alginate multilayer was fabricated.•miRNA were in situ released to osteoblasts upon degradation of the multilayer.•Multilayer enhanced surface osteoblasts proliferation and early differentiation.Micro-RNA (miRNA) gene therapy is a viable approach for enhancing implant osseointegration for clinical applications. However, an efficient in situ delivery system for coating the implants is needed. The present study combined dopamine-modified alginate and miRNA to construct multiple layers on titanium surface using the layer-by-layer technique. Water contact angle tests and fluorescence microscopy results showed that miRNAs were successfully loaded onto the multilayer. The in situ release behavior of miRNA was monitored and their transfection was confirmed by the fluorescence microscopy. Results from osteoblast viability tests showed that the multilayer significantly enhanced cell proliferation. Alkaline phosphatase activity was enhanced by the multilayer as well. In conclusion, the multilayer coating can serve as an effective in situ delivery method for miRNAs and can significantly enhance osteoblast proliferation and early differentiation.

Anatase TiO2 nanoplates, with average side length ranging from 90 to 200 nm and average thickness ranging from 20 to 60 nm, were successfully fabricated by annealing anodized TiO2 nanotubes with different heating rates. The as-synthesized TiO2 nanoplates and nanotubes were analyzed by field-emission scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and transmission electron microscopy. To investigate the growth mechanism of the TiO2 nanoplates dominated by highly reactive {001} facets, different heating rates were applied appropriately during the thermal treatment. The results revealed that the heating rate during thermal treatment is critical in determining the nanostructure of anatase TiO2. The fast heating rate (samples were annealed when the temperature heated up to 450 °C) and the brittle property are the main reasons for the collapse of the anodized TiO2 nanotubes. The nanosized TiO2 species grow into TiO2 nanoplates with the exposed 60 % of {001} facets because the fluorated surface of TiO2 species can direct the formation of TiO2 nanoplates with exposed {001} facets. The photoactivity of the TiO2 nanoplates is higher than that of TiO2 nanotubes.

Surface microstructure and chemical composition of the implant are very important for its osseointegration in vivo. In this paper, a hierarchical micropattern covered with calcium phosphate (Ca/P phase) was obtained on titanium (Ti) implant surface by femtosecond lasers (FSL) irradiation in hydroxyapatite suspension. The hierachical micropattern as well as Ca/P phase increased osteoblastic cell adhesion. Higher expression of osteogenic markers (osteocalcin, osteopontin, and runt related transcription factor-2) on the surface treated by FSL of 2.55 J/cm2 indicated the favorable effect of laser treatment on cell differentiation. In vivo studies were carried out to evaluate the effect of laser treatment and Ca/P deposition on the osseointegration. It showed that the binding capacity between bone and FSL-treated Ti implants was obviously stronger than that between bone and polished or sand blasting and acid etching (SLA) Ti implants. Bone trabecula surrounded the FSL-treated implants without fibrous tissue after 8-week implantation. Also, higher bone mineral density was seen surrounding the FSL-treated implants. Our in vitro and in vivo studies demonstrated that the FSL induced micropattern and Ca/P phase had positive effects on the acceleration of early osseointegration of Ti implants with bone tissue.Keywords: Ca/P phase; femtosecond lasers; micropatterning; osseointegration; Ti implant;

SnSe and silver (Ag) nanoparticles were sequentially deposited on TiO2 nanotube (NT) by pulsed electrochemical deposition and polyol chemistry process, respectively. The morphological observation under scanning electron microscope (SEM) showed that the average size of SnSe was about 30 nm and the Ag was about 5 nm. Transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED) examination indicated that Ag nanoparticles exhibited a well-defined crystallinity. However, SnSe nanoparticles were amorphous and they turned to crystalline after being annealed at 300 °C in the atmosphere. The photocatalytic behavior of SnSe/Ag-TiO2 NT was evaluated by UV–vis diffuse reflectance spectra (DRS). The results showed that the deposition of SnSe and Ag nanoparticles increased light absorption intensity in the wavelength range of visible light, which implied that the SnSe/Ag-TiO2 NT is a promising ternary hybrid material in photocatalysis.Graphical abstractHighlight► The SnSe and Ag nanoparticles co-modified TiO2 nanotube (NT) was fabricated. ► The average size of SnSe was about 30 nm and the Ag was about 5 nm. ► Both SnSe and Ag exhibited a well distribution density on TiO2 NT. ► UV–vis absorption spectra of SnSe/Ag-TiO2 NT exhibited obvious redshift.

Tetrathiafulvalene (TTF) was one of the most widely studied heterocyclic systems. However, TTF itself was easily oxidized, which induced the low stability and limited its potential applications. Here, a TTF derivative, 2,3,6,7-tetrakis(2-cyanoethylthio)tetrathiafulvalene (TCE-TTF), was synthesized. It was found that single crystalline micro- and nanowires of TCE-TTF were easily obtained by simple casting due to the enhanced π–π overlapping and S⋯S interaction. The thermal and vacuum stability analyses revealed TCE-TTF was much better than TTF. Single crystalline micro- and nanowires field-effect transistors were also fabricated by in situ dropping method. The typical mobility and on/off ratio were ∼0.02 cm2/V s and ∼103, which predicted great potential applications of organic nanowires electronics.

In this study, the self-organized TiO2 nanotubes grown by anodization of Ti–4Zr–22Nb–2Sn at different potentials, concentration of NH4F and anodization time was investigated. The morphology of nanotubes was observed by FE-SEM. The drug-loaded nanotubes were also fabricated in aqueous media containing minocycline hydrochloride. They were characterized by SEM, XPS and FT-IR. The results showed that the drug of minocycline hydrochloride (MH) was loaded in the nanotubes. The release effects were studied in phosphate buffer solution (PBS). The release rate of MH from TiO2 nanotubes with shorter tube length in PBS was lower than the one of MH from longer nanotubes. The sustaining release time could last at least 150 h. Hence, it is a promising method to eliminate the harmful reactions by carrying drug in the tubes when the titanium alloys were used as biomedical implants.

The iron oxide nanoparticles were loaded onto self-organized TiO2 nanotube layers grown by anodization of Ti in fluoride containing electrolytes. The nanoparticles were obtained by electrodepositing method in glycerol/water/FeCl3·6H2O electrolytes at room temperature. The X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) measurements showed that the nanoparticles consisted of iron nanocrystalline (Fe) and magnetite (Fe3O4). The hematite (α-Fe2O3) structure was obtained by annealing in air at 450 °C. The growth mechanism of the nanoparticles and their morphology were also described. Furthermore, the nanoparticles exhibited good ferromagnetic properties at room temperature.

Femtosecond laser processing is employed to create regular patterns and bioactive layer on the surface of pure titanium. Surface morphology and microstructure of the laser-processed layer are characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the processing with varied laser energies builds a surface with three-order roughness from nanometer scale to micrometer scale. Selected area electron diffraction indicates that some kind of TiO layer emerges on the surface after femtosecond laser machining. The bioactivity of TiO layer is further evaluated by soaking it in simulated body fluid (SBF). SEM observation and EDX analysis show that Ca/P layer is rapidly formed on the surface of TiO layer after SBF soaking. It implies that TiO layer with unique three-order roughness has good bioactivity.

Porous microstructures on Nickel-Titanium (NiTi) alloy surfaces were prepared by linearly polarized femtosecond lasers with moving focal point at a certain speed. It was found that various novel microstructures from feather-like ripples to cluster-like porous textures could be formed with increasing laser energy. Particularly, when the laser energy was 400 μJ, a periodic porous metal surface was generated. Measurement of X-ray diffraction showed that the grains on the sample surface were refined through femtosecond laser ablation processes, but the crystal structures still kept their original states. Analysis by X-ray photoelectron spectroscopy revealed that Ni/Ti on the sample surface was changed with an evident oxidization of titanium element under different laser energies. This investigation provides a new approach to improve the biocompatibility of NiTi-based implant devices.

The spider is well known for sensing the movements of air and preys. Bionics of the spider based on this principle is being paid great attention by many researchers. Here, this paper presents some detailed organs of the spider to make an attempt to clarify the sensing mechanism of the spider from the point view of physical structure by scanning electron microscopy. And behavior characteristics concerning sensing action are observed by optical microscopy. Compared with structures, some novel features of sense movements in micro- and nano-scale size and corresponding possible models are presented. At the same time, simple structure analysis is made to explain and prove this hypothesis.

Silver (Ag) nanoparticles were successfully assembled in self-organized TiO2 nanotubes by the polyol process. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy as well as Fourier transform infrared spectroscopy were used for the characterization of surface morphology, phase composition, microstructure, and valent state of the AgTiO2 catalysts. It was found that these catalysts showed improved dispersion and increased catalytically active sites. The electrocatalytic properties of AgTiO2 catalysts for ethanol oxidation were investigated by cyclic voltammetry. The results showed that the Ag doped anatase TiO2 composites exhibited excellent catalytic activity in electrocatalytic ethanol oxidation in alkaline media. Hence, the composites look promising in direct ethanol fuel cell applications.Graphical abstractThe TEM micrographs for Ag doped TiO2 nanotubes annealed at 723 K and the cyclic voltammograms in acidic and alkaline media.Download high-res image (52KB)Download full-size imageResearch highlights► Silver nanoparticles deposited on TiO2 nanotubes as catalysts. ► A small amount of Ag atoms can diffuse into the lattice of rutile TiO2. ► The AgTiO2/723 K coatings have the best catalytic activity.

Magnesium (Mg) and strontium (Sr) have been widely used in the field of implanted devices because of their excellent bioactivity. However, the local high ion concentration caused by the implant affects the growth of hydroxyapatite (Ca10(PO4)6(OH)2, HA), which is the main inorganic component of bone and teeth. Many studies have investigated the effect of Mg2+ and Sr2+ on the growth of HA, but no systematic research has been conducted to compare these two ions in terms of the growth of HA. In this study, the substitution of a series of Sr- and Mg-substituted HA was conducted through a conventional hydrothermal method. Comprehensive characterization techniques, including X-ray diffraction, inductive coupled plasma, field emission scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, thermo gravimetric-differential scanning calorimetry, and Fourier transform infrared spectroscopy, were used to examine the effects of Sr2+ and Mg2+ on the phase, morphology, crystallinity, chemical composition, thermal stability, and lattice parameters of HA. The results indicated that Mg ions partially substituted for calcium (Ca) ions in the apatite structure, thus decreasing the lattice parameters, partially adsorbing on the apatite surface that formed the amorphous phase, and inhibiting the crystal growth. By contrast, Sr ions fully substituted for Ca ions and increased the lattice parameters. Both Mg and Sr ions affected the morphology of HA. Crystallinity decreased with the addition of Mg ions (transition from the crystal to amorphous phase was between 30% and 40% Mg), but it was not affected by Sr ions. Thermostability decreased with the addition of Mg (a total weight loss from 8.06 wt% for 10% Mg to 25.81 wt% for 50% Mg), but it had no significant changes in the Sr-substituted samples.