Study on the In Vitro and In Vivo Antibacterial Activity and Biocompatibility of Novel TiN/Ag Multilayers Immobilized onto Biomedical Titanium.

To determine the short- and long-term antibacterial properties of a novel biomedical titanium alloy to ensure excellent biocompatibility of the TiN/Ag multilayers loaded with different doses of Ag+. First, nanosized TiN/Ag multilayers were accumulated onto titanium alloy (Ti-6Al-4V) substrates via multi-arc ion plating. Then, the multilayers were implanted with different doses of silver ions (1×1017 ions/cm², 1×1018 ions/cm², 5×1016 ions/cm², and 5×1017 ions/cm²). Both short- and long-term antibacterial properties against Streptococcus mutans and Staphylococcus aureus were assessed via unique methods. Additionally, the response and behaviors of MC3T3-E1 and L929 cells on the different surfaces were evaluated by a variety of methods through comparison to a normal matched substrate (Ti-6Al-4V). In Vitro and In Vivo analyses revealed that the multilayers containing different doses of Ag ions effectively prevented bacterial adhesion and eliminated the majority of adhered bacteria in the initial period. In addition, the antibacterial activity of each TiN/Ag group improved with time, with the antibacterial rate (Ra) ultimately reaching 99% (antibacterial activity: 1 × 1018 ions/cm² > 5 × 1017 ions/cm² > 1 × 1017 ions/cm² > 5 × 1016 ions/cm²). All of the samples loaded with Ag+ exhibited good compatibility, as well as higher cell proliferation and lower apoptosis than the pure Ti-6Al-4V substrates. Considering both bacteriostasis and biocompatibility, 1 × 1017 ions/cm² and 5 × 1017 ions/cm² are the recommended doses for orthopedic and dental implants. The results indicate that all of the samples loaded with Ag+ possess excellent biocompatibility and antibacterial activity against common bacteria that cause implantation infection. The samples loaded with Ag+ can be implanted into soft and hard growing tissues to greatly improve the survival rate of orthopedic and dental implants.

Shape-Control of Three-Dimensional Self-Assembly Graphene by Hydrothermal Reaction Time and Its Biological Application.

In this paper, three-dimensional self-assembly graphene (3D-G) was prepared by the hydrothermal synthesis method, and 3D-G was designed as a suitable biological scaffold for cell growth and adhesion. The shape of 3D-G was tuned by adjusting the hydrothermal reaction time (6 h, 12 h, 18 h and 24 h). Then the scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses were used to characterize the microstructure and component of 3D-G, which showed that the length, diameter, pore size and defects of 3D-G were all decreased as the reaction-time increased. In vitro cell culture experiment, the cytocompatibility of 3D-G prepared under different hydrothermal reaction time was assessed using mouse fibroblast cells (L929) via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT). Meanwhile, the cell adhesion, growth and proliferation were also observed by SEM. These results showed that the 3D-G with the reaction time of 24 h (3D-G/24 h) had the best cytocompatibility, which could be used as tissue scaffolds for cell growth.

Enhanced anti-microbial activity and osseointegration of Ta/Cu co-implanted polyetheretherketone.

Polyetheretherketone (PEEK) has been widely applied for orthopedic and oral implants due to its excellent mechanical properties, biocompatibility, and radiolucency. However, its bioinert and the lack of anti-microbial activity limit its application. We modified the PEEK surface with Ta/Cu co-implantation using plasma immersion ion-implantation technology. After implantation of Ta/Cu ions, the morphology and roughness of the PEEK surface were not significantly changed at micron level. We estimated the cytocompatibility, anti-microbial ability, and osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs) of the modified surfaces in vitro. Compared to the untreated surfaces, the Ta ion-treated surface showed improved adhesion, proliferation, ALP activity, ECM mineralization, and osteogenic gene expression of BMSCs. Further, the Cu ion-treated surface showed reduced initial adhesion and proliferation of Escherichia coli and Staphylococcus aureus in vitro and proliferation of Staphylococcus aureus in the mouse subcutaneous implant-associated infection model. According to a rat bone repair model, all Ta ion-implanted groups demonstrated improved new bone formation. In summary, Ta/Cu ion co-impanation improved anti-microbial activity and promoted osseointegration of the PEEK surface.

Peroxidase- and UV-triggered oxidase mimetic activities of the UiO-66-NH2/chitosan composite membrane for antibacterial properties.

In this study, UiO-66-NH2 metal-organic framework (MOF) nanoparticles with peroxidase and oxidase mimetic activities were incorporated into a chitosan (CS) matrix by a simple and environmentally friendly method. The UiO-66-NH2/CS composite membrane possesses the peroxidase mimicking activity in the presence of traces of H2O2, thus resulting in good antibacterial properties. Intriguingly, 30 min of UV pre-irradiation of the UiO-66-NH2/CS composite membrane, in the absence of H2O2, still leads to a good antibacterial activity. This was attributed to the oxidase mimetic activity and the peroxidase mimicking activity of UiO-66-NH2. In such a way, the side effects of direct exposure to UV irradiation and H2O2 can be avoided for wound-healing treatments. The antibacterial mechanism was further proved by antibacterial experiments, TMB·2HCl color development experiments, reactive oxygen species generation tests and electron spin resonance tests. As a potential medical antibacterial dressing, in vitro membranes were also investigated.

Well-water-dispersed N-trimethyl chitosan/Fe3O4 hybrid nanoparticles as peroxidase mimetics for quick and effective elimination of bacteria.

Fe3O4 nanoparticles, used as peroxidase mimetics, exhibit splendid future in the biomedical field. However, the functionalization on Fe3O4 nanoparticles always goes with the loss of superparamagnetism and decrease in peroxidase-activity. Here, we synthesized green polyethylene glycol (PEG)-functionalized magnetic/N-trimethyl chitosan (CS) hybrid nanoparticles (Fe3O4@PAA/TMC/PEG NPs) with improved water dispersibility, superparamagnetism, high saturation magnetization and well peroxidase-like activity. The functionalized coating was divided in two steps, one involved a cross-linked PEG/PAA/CS middle layer to protect the nanocrystal Fe3O4 from oxidization, the other was a hydrophilic PEG/TMC outer layer improving the water dispersion, biocompatibility, as well as supplying positive quaternary ammonium groups for a potential increase of cell binding efficiency. The structure, composition and morphology of Fe3O4@PAA/TMC/PEG NPs were characterized by TEM, FT-IR spectroscopy, DLS, zeta potential measurement, respectively. Thermal performance was characterized by TGA, and the peroxidase-like mimics activity was tested by TMB·2HCl colour development experiments. The magnetic property of the as-prepared hybrid nanoparticles was first confirmed by VSM, and then proved by the bacterial pathogens adsorption, especially at ultralow pathogen concentration. Particularly, with an external magnet, the Fe3O4@PAA/TMC/PEG NPs, combined cationic quaternary ammonium groups and peroxidise-mimetic catalytic activity, were tested for antibacterial effect by plating method.

Study on the osteogenesis of rat mesenchymal stem cells and the long-term antibacterial activity of Staphylococcus epidermidis on the surface of silver-rich TiN/Ag modified titanium alloy.

The main causes of failure of orthopedic implants are infection and poor bone ingrowth. Surface modification of the implants to allow for long-term antibacterial and osteogenic functions is an effective solution to prevent failure of the implants. We developed silver-rich TiN/Ag nano-multilayers on the surface of titanium alloy with different doses of Ag+ . The antibacterial stability and osteogenesis of the silver-rich surface were determined by evaluating the adhesion and proliferation of Staphylococcus epidermidis, and the adhesion, proliferation, alkaline phosphatase activity, extracellular matrix mineralization, and the expression level of genes involved in osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs). The results demonstrated that the antibacterial rates (Ra) of 5 × 1016 -Ag, 1 × 1017 -Ag, 5 × 1017 -Ag, and 1 × 1018 -Ag were respectively 46.21%, 85.66%, 94.99%, 98.48%, and 99.99%. After subcutaneous implantation in rats or immersion in phosphate buffered saline for up to 12 weeks, the silver-rich surface of the titanium alloy showed long-term stable inhibition of Staphylococcus epidermidis. Furthermore, in vitro and in vivo studies indicated that the Ag-implanted titanium did not show apparent cytotoxicity and that lower Ag+ implanted groups (5 × 1016 -Ag, 1 × 1017 -Ag) had better viability and biological safety when compared with higher Ag+ implanted groups. In addition, when compared with the Ti6Al4V-group, all Ag-implanted groups exhibited enhanced osteogenic indicators in rat BMSCs. Regarding osteogenic indicators, the surfaces of the 5 × 1017 -Ag group had better osteogenic effects than those of other groups. Therefore, the proper dose of Ag+ implanted TiN/Ag nano-multilayers may be one of the options for the hard tissue replacement materials with antibacterial activity and osteogenic functions.

Enhanced cell growth on 3D graphene scaffolds implanted with nitrogen ions.

One of the key challenges in engineering tissues for cell-based therapies is developing biocompatible scaffold materials to direct cell behavior. In this paper, the cytocompatibilities of a flexible three-dimensional graphene scaffold (3D-G) and the same scaffold implanted with nitrogen ions (N+/3D-G) are compared using an in vitro assay based on 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The N+/3D-G samples were prepared from low-temperature hydrothermally synthesized flexible 3D-G by ion implantation and were found to display improved adhesion and proliferation of rat osteoblast and mouse fibroblast cells. In particular, the N+/3D-G sample with a nitrogen content of ∼10% showed the highest levels of cell viability and proliferation. The flexible N+/3D-G has potential applications as a biocompatible scaffold material that provides improved surface area and hydrophilic groups for cell growth and proliferation.

N+ implantation induce cytocompatibility of shape-controlled three-dimensional self-assembly graphene.

AIM: The aim of the present research was to synthesize N+ implanted 3D self-assembly graphene (N+/3D-SGHs) to overcome the weaknesses of graphene (small sizes and poor hydrophilicity) in tissue engineering scaffolds. MATERIALS & METHODS: N+/3D-SGHs was achieved by ion implantation on one-step hydrothermal synthesized 3D self-assembly graphene (3D-SGHs), and N+/3D-SGHs with different doses of nitrogen ions (1 × 1016 ions/cm2, 1 × 1018 ions/cm2 and 1 × 1020 ions/cm2), which adjusted by nitrogen ion beam intensity. RESULTS: N+/3D-SGHs, as scaffolds, provide stereo space and hydrophilic groups for mouse-fibroblast cells (L929) growth and proliferation. Notably, N+/3D-SGHs with the N+ injected quantity of 1 × 1020 ions/cm2 displayed the highest protein-adhesion strength, cell viability and proliferation, which supported its good cytocompatibility. CONCLUSION: This study demonstrated N+/3D-SGHs as a promising and effective tissue scaffold that might have applications in biomedicine.

Ag+ implantation induces mechanical properties, cell adhesion and antibacterial effects of TiN/Ag multilayers in vitro.

AIM: This study aims to investigate the effect of Ag+ implantation dose on the structure, hardness, adhesion strength, friction resistance, cell adhesion and antibacterial effects of TiN/Ag multilayers. METHODS: Nanoscale TiN/Ag multilayers were deposited on Ti-6Al-4V substrates using multiarc ion plating. The multilayers were then implanted by Ag ions. RESULTS: A distinct multilayer structure and large titanium nitride grains with better (111) crystallinity were proved. The hardness and elastic modulus of the multilayer reached 32.2 and 318.9 GPa, respectively. The largest critical load was 32.5 mN, and the minimum friction coefficient was 0.092. The mechanical properties, the cell proliferation and antibacterial properties of the multilayers with Ag+ implantation were better than those without Ag+ implantation. CONCLUSION: Our results indicate that a dose of 1 × 1017 ions/cm2 induced an improvement in crystallinity, mechanical properties, as well as preferable cell adhesion and antibacterial effects.

Enhancement of interaction of L-929 cells with functionalized graphene via COOH+ ion implantation vs. chemical method.

Low hydrophilicity of graphene is one of the major obstacles for biomaterials application. To create some hydrophilic groups on graphene is addressed this issue. Herein, COOH+ ion implantation modified graphene (COOH+/graphene) and COOH functionalized graphene were designed by physical ion implantation and chemical methods, respectively. The structure and surface properties of COOH+/graphene and COOH functionalized graphene were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurement. Compared with graphene, COOH+/graphene and COOH functionalized graphene revealed improvement of cytocompatibility, including in vitro cell viability and morphology. More importantly, COOH+/graphene exhibited better improvement effects than functionalized graphene. For instance, COOH+/graphene with 1 × 1018 ions/cm2 showed the best cell-viability, proliferation and stretching. This study demonstrated that ion implantation can better improve the cytocompatibility of the graphene.

Influence of Content of Al2O3 on Structure and Properties of Nanocomposite Nb-B-Al-O films.

Nb-B-Al-O nanocomposite films with different power of Al2O3 were successfully deposited on the Si substrate via multi-target magnetron co-sputtering method. The influences of Al2O3's content on structure and properties of obtained nanocomposite films through controlling Al2O3's power were investigated. Increasing the power of Al2O3 can influence the bombarding energy and cause the momentum transfer of NbB2. This can lead to the decreasing content of Al2O3. Furthermore, the whole films showed monocrystalline NbB2's (100) phase, and Al2O3 shaded from amorphous to weak cubic-crystalline when decreasing content of Al2O3. This structure and content changes were proof by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). When NbB2 grains were far from each other in lower power of Al2O3, the whole films showed a typical nanocomposite microstructure with crystalline NbB2 grains embedded in a matrix of an amorphous Al2O3 phase. Continuing increasing the power of Al2O3, the less content of Al2O3 tended to cause crystalline of cubic-Al2O3 between the close distances of different crystalline NbB2 grains. The appearance of cubic-crystallization Al2O3 can help to raise the nanocomposite films' mechanical properties to some extent. The maximum hardness and elastic modulus were up to 21.60 and 332.78 GPa, which were higher than the NbB2 and amorphous Al2O3 monolithic films. Furthermore, this structure change made the chemistry bond of O atom change from the existence of O-Nb, O-B, and O-Al bonds to single O-Al bond and increased the specific value of Al and O. It also influenced the hardness in higher temperature, which made the hardness variation of different Al2O3 content reduced. These results revealed that it can enhance the films' oxidation resistance properties and keep the mechanical properties at high temperature. The study highlighted the importance of controlling the Al2O3's content to prepare well-defined films with high mechanical properties and thermal stability.

In vivo implantation of hydrophobic acrylic intraocular lenses with surface modification.

PURPOSE: To assess the surface properties of modified hydrophobic acrylic intraocular lenses (IOL) implanted in rabbits. METHODS: The hydrophobic acrylic IOLs were modified with monomer vinyl pyrrolidone by surface modification technique. Phacoemulsification combined with IOL implantation was conducted in 9 rabbits (18 eyes). Postoperative responses were observed by slit-lamp microscope at 3, 7, 15, 30, 90 days after surgery. RESULTS: During the early stage after IOL implantation, corneal edema and anterior chamber fibrin exudation were observed. The exudate fluid was almost absorbed at the 15th day postoperatively. At 7th day, the anterior chamber exudation in the modification group was significantly less severe than that in non-modification group (P < 0.05). Posterior capsular opacification occurred at 30th day after surgery and was aggravated 90 days later. IOL dislocation was seen in 5 eyes and occlusion of pupil in 3 eyes. CONCLUSION: The hydrophobic acrylic IOLs with surface modification have improved surface properties and higher uveal biocompatibility.

NH2+ implantations induced superior hemocompatibility of carbon nanotubes.

NH2+ implantation was performed on multiwalled carbon nanotubes (MWCNTs) prepared by chemical vapor deposition. The hemocompatibility of MWCNTs and NH2+-implanted MWCNTs was evaluated based on in vitro hemolysis, platelet adhesion, and kinetic-clotting tests. Compared with MWCNTs, NH2+-implanted MWCNTs displayed more perfect platelets and red blood cells in morphology, lower platelet adhesion rate, lower hemolytic rate, and longer kinetic blood-clotting time. NH2+-implanted MWCNTs with higher fluency of 1 × 1016 ions/cm2 led to the best thromboresistance, hence desired hemocompatibility. Fourier transfer infrared and X-ray photoelectron spectroscopy analyses showed that NH2+ implantation caused the cleavage of some pendants and the formation of some new N-containing functional groups. These results were responsible for the enhanced hemocompatibility of NH2+-implanted MWCNTs.

In vitro comparison of the hemocompatibility of diamond-like carbon and carbon nitride coatings with different atomic percentages of N.

Carbon nitride (CN( x )) and diamond-like carbon (DLC) coatings were prepared by dc magnetron sputtering at room temperature. Different partial pressures of N(2) were used to synthesize CN( x ) to evaluate the relationship between the atomic percentage of nitrogen and hemocompatibility. Auger electron spectroscopy and atomic force microscopy indicated atomic percentages of N of 0.12 and 0.22 and that the CN( x ) coatings were smooth. An in vitro study of the hemocompatibility of the coatings revealed that both CN( x ) coatings had better anticoagulant properties and lower platelet adhesion than DLC. Compared with CN(0.12), the CN(0.22) coating showed longer dynamic clotting time (about 42 min), static clotting time (23.6 min) and recalcification time (45.6 s), as well as lower platelet adhesion (102 cells µm(-2)), aggregation, and activation. The presence of nitrogen in the CN( x ) coatings induced their enhanced hemocompatibility compared with DLC.