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Early biofilm formation could be inhibited by applying a thin biocompatible copper coating to reduce periprosthetic infections. In this study, we deposited crystalline Cu-doped TiO2 films using one-step DC magnetron sputtering in an oxygen atmosphere on a biased Ti6Al4V alloy without external heating. The bias voltage varied from −25 V to −100 V, and the resultant substrate temperature was measured. The deposited coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness, scratch and hydrophilicity tests, potentiodynamic polarization measurements, and antibacterial assays against S. aureus and E. coli. The findings demonstrated that when a higher negative bias is applied, the substrate temperature drops, and the anatase to rutile transformation is initiated without indicating obvious Cu-containing phases. The SEM images of the films showed spherical agglomerates with homogeneously distributed Cu with decreasing Cu content as the bias value increased. Higher bias results in the grain refinement of the thinning coatings with more lattice microstrain and more defects, together with an increase in water contact angles and hardness values. Samples biased at −75 V exhibited the highest adhesive strength between coatings and substrate, whereas the specimen biased at −50 V demonstrated higher corrosion resistance. Cu-containing TiO2 coatings with pure anatase phase composition and Cu concentrations of 2.62 wt.% demonstrated excellent bactericidal activity against both S. aureus and E. coli. The layers containing 2.34 wt.% Cu exhibited very good antibacterial properties against S. aureus, only. According to these findings, the produced copper-doped TiO2 coatings have high bactericidal qualities in vitro and may be used to prepare orthopaedic and dental implants in the future. [ABSTRACT FROM AUTHOR]

One of the primary risk factors for implant failure is thought to be implant-related infections during the early healing phase. Developing coatings with cell stimulatory behaviour and bacterial adhesion control is still difficult for bone implants. This study proposes an approach for one-step deposition of biocompatible and antimicrobial Cu-doped TiO2 coatings via glow-discharge sputtering of a mosaic target. During the deposition, the bias of the Ti6Al4V substrates was changed. Structure examination, phase analysis, and surface morphology were carried out using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The hardness values and hydrophilic and corrosion performance were also evaluated together with cytocompatible and antibacterial examinations against E. coli and S. aureus. The results show great chemical and phase control of the bias identifying rutile, anatase, CuO, or ternary oxide phases. It was found that by increasing the substrate bias from 0 to −50 V the Cu content increased from 15.3 up to 20.7 at% while at a high bias of −100 V, the copper content reduced to 3 at%. Simultaneously, apart from the Cu2+ state, Cu1+ is also found in the biased samples. Compared with the bare alloy, the hardness, the water contact angle and corrosion resistance of the biased coatings increased. According to an assessment of in vitro cytocompatibility, all coatings were found to be nontoxic to MG-63 osteoblast cells over the time studied. Copper release and cell-surface interactions generated an antibacterial effect against E. coli and S. aureus strains. The −50 V biased coating combined the most successful results in inhibiting bacterial growth and eliciting the proper responses from osteoblastic cells because of its phase composition, electrochemical stability, hydrophilicity, improved substrate adhesion, and surface roughness. Using this novel surface modification approach, we achieved multifunctionality through controlled copper content and oxide phase composition in the sputtered films. [ABSTRACT FROM AUTHOR]

Magnesium hydroxide (Mg(OH)2) nanoflakes were synthesized by surfactant-assisted sonochemical route with using of natural brine (containing MgCl2), NaOH, and polyethylene glycol as magnesium procedure, precipitator, and surfactant, respectively. The effect of ultrasound irradiation power was investigated in 3 levels (100, 200, and 350 W) on optical, structural, and morphological properties and thermal behavior of as-prepared magnesium hydroxide (MH) nanostructures. XRD, DLS, FESEM, TEM, EDS, FTIR, BET, and UV–visible spectroscopy techniques characterized the synthesized samples. XRD profiles and FESEM and TEM images of all as-synthesized samples disclosed that the Mg(OH)2 nanoflakes indicate hexagonal brucite-type crystallinity with space group P-3m1 without any impurity phases. Also, the crystallite size of samples was increased from 21 to 27 nm by incrementing the ultrasound irradiation power from 100 to 350 W, respectively. Due to the polycrystalline nature of the particles, the size of nanoflakes measured with DLS were 80, 105 and 140 nm for 100, 200, and 350 W irradiation powers, respectively. Well-dispersed Mg(OH)2 nanoflakes with a uniform size distribution were obtained using 100 W irradiation power. Also, FESEM and TEM images confirmed that increasing the ultrasonic wave power led to the accumulation of flakes, which based on BET studies can be due to the reduction of the specific surface area of nanoflakes from 115 m2/g (for 100 W irradiation) to 35 m2/g (for 350 W irradiation). The optical band gap energy of the nanoflakes was found to be slightly decreased with increasing with the increase of ultrasound irradiation power content. [ABSTRACT FROM AUTHOR]

In response to alphabeta1 integrin signaling, transducers such as focal adhesion kinase (FAK) become activated, relaying to specific machineries and triggering distinct cellular responses. By conditionally ablating Fak in skin epidermis and culturing Fak-null keratinocytes, we show that FAK is dispensable for epidermal adhesion and basement membrane assembly, both of which require alphabeta1 integrins. FAK is also dispensible for proliferation/survival in enriched medium. In contrast, FAK functions downstream of alphabeta1 integrin in regulating cytoskeletal dynamics and orchestrating polarized keratinocyte migration out of epidermal explants. Fak-null keratinocytes display an aberrant actin cytoskeleton, which is tightly associated with robust, peripheral focal adhesions and microtubules. We find that without FAK, Src, p190RhoGAP, and PKL-PIX-PAK, localization and/or activation at focal adhesions are impaired, leading to elevated Rho activity, phosphorylation of myosin light chain kinase, and enhanced tensile stress fibers. We show that, together, these FAK-dependent activities are critical to control the turnover of focal adhesions, which is perturbed in the absence of FAK.

To fix the bone in orthopedics, it is almost always necessary to use implants. Metals provide the needed physical and mechanical properties for load-bearing applications. Although widely used as biomedical materials for the replacement of hard tissue, metallic implants still confront challenges, among which the foremost is their low biocompatibility. Some of them also suffer from excessive wear, low corrosion resistance, infections and shielding stress. To address these issues, various coatings have been applied to enhance their in vitro and in vivo performance. When merged with the beneficial properties of various bio-ceramic or polymer coatings remarkable bioactive, osteogenic, antibacterial, or biodegradable composite implants can be created. In this review, bioactive and high-performance coatings for metallic bone implants are systematically reviewed and their biocompatibility is discussed. Updates in coating materials and formulations for metallic implants, as well as their production routes, have been provided. The ways of improving the bioactive coating performance by incorporating bioactive moieties such as growth factors, osteogenic factors, immunomodulatory factors, antibiotics, or other drugs that are locally released in a controlled manner have also been addressed. [ABSTRACT FROM AUTHOR]

Equal channel angular extrusion (ECAE) has shown great potential for the consolidation of powdered materials. In the present article, the mechanical and corrosion properties of Mg-MgO and Mg-Al2O3 composites produced by the ECAE method were studied. Pure magnesium reinforced with 0, 10, 20, and 30 vol percentages of MgO and Al2O3 particles were hot consolidated at 600 MPa in an ECAE die without prior cold compaction or canning of the powders. Results indicated that the reinforcement content is directly proportional to the hardness, compressive strength, and corrosion resistance of the fabricated composites, while it has an inverse relationship with the relative density. The lowest relative density and the highest corrosion rate were obtained for the Mgþ30%MgO composite samples, as opposed to the pure magnesium with the highest relative density and the lowest corrosion rate. Besides, composites reinforced with 30 and 20 vol percentages of alumina revealed the highest hardness and the highest compressive strength, which were 55% and 74% higher than that of the pure magnesium sample, respectively. Based on SEM and EDX analyses, it was shown that Mg-Al2O3 samples had finer grain sizes compared to Mg-MgO composites. [ABSTRACT FROM AUTHOR]

Each printing method and the materials used for prototype construction have distinct advantages and drawbacks. A large part of the 3D printer producers indicates high printing accuracy (positioning accuracies from 100 μm up to 1 μm and layer thickness from 100 μm tо 5 μm). In the process of layers deposition, the material is softened, melted or irradiated with a certain light source to polymerize. Thus, during the printing process, the volume of the materials is changing causing shrinking or expansion which often leads to the occurrence of precision errors in the prototype as opposed to the digital model. This phenomenon leads to distortions of the printed object known as a curling effect. Certain chemical compounds are added by the producers to multiple materials in order to enhance their mechanical and technological properties. However, this often results in changes of some printing parameters influencing the precision and quality of the manufactured object. The aim of the particular study is to establish the allowances with regard to the accuracy during manufacturing precise objects used in micro technologies as well as the necessary adjustments in dimensions because of the shrinkage and the positioning of the SLA 3D printed parts from photopolymer material.

Due to the generalized use of aluminium (Al) and Al alloy a detailed investigation of the mechanical and technological behaviour of a wide range of sheet metals is particularly needed. Often during deformation the Al sheets fold or crack which makes their subsequent use harder. The aim of this study is to identify the causes of the changes taking place during deformation that leads to earlier breaks of the Al sheet material. Pure ENAW-Al99.5 in as-received condition is used for examination in order to determine its behaviour without interference of the alloying elements. After the uniaxial uniform tensile test significant differences in the mechanical strength of the samples cut out from the sheet material at three different directions - 0°, 45° and 90° angle to the rolling direction are observed. The hardness values measured at three different directions: alongside the long side of the samples, cross-section and top view are compared. The XRD and microstructure analysis confirm the grain and lattice reorientation after the tests compared with the initial structure of the sheet material. These results could be applied as a basis of comparison when examining other Al alloys used in aviation and mechanical engineering, chemical and agro-food industry, etc.

Composite materials are currently used in many fields of activity. These materials have different compositions and show very good mechanical and technological properties. A field where these composite materials have applicability is that of metal coatings. In the present work, these composite materials are presented, how they are applied and how they manifest themselves on the materials on which they are deposited. [ABSTRACT FROM AUTHOR]