The Role of Dendritic Cells in Bone Loss and Repair

The cells of innate immunity, such as neutrophils, macrophages, and dendritic cells (DCs), stuck to the bone implant walls release reactive radicals, enzymes, and chemokines, which induced subsequent bone loss. DCs do not play a big role in bone homeostasis in steady-state conditions, but could act as osteoclasts precursors in inflammation foci of bone. The potent antigen-presenting cells responsible for activation of native T cells and modulation of T cell activity through RANK/RANKL pathway and other cytokines associated with osteoclastogenesis determine critically situated at the osteoimmune interface. The titanium (Ti) and magnesium (Mg), the metallic candidate in implant, including calcium-phosphate coating formation on them by method plasma electrolytic oxidation were used to evaluate the immune-modulatory effects of DCs. The calcium-phosphate coating on metals induced mature DC (mDC) phenotype, while Ti and Mg promoted a noninflammatory environment by supporting an immature DC (iDC) phenotype based on surface marker expression, cytokine production profiles, and cell morphology. These findings have numerous therapeutic implications in addition to DC’s important role in regulating innate and adaptive immunity. A direct contribution of these cells to inflammation-induced bone loss establishes DC as a promising therapeutic target, not only for controlling inflammation but also for modulating bone destruction

Effect of carbon nanotubes incorporation on the properties of the PEO coatings formed on MgMn-Ce alloy

The properties of coatings formed on the MA8 magnesium alloy by the plasma electrolytic oxidation in electrolytes containing multi-walled carbon nanotubes in concentrations of 2, 4 and 6 g/l have been investigated. It was found that the introduction of multi-walled carbon nanotubes leads to an increase in the adhesive strength, microhardness and Young’s modulus of the obtained layers

Physicochemical studies of composite coatings during accelerated tests for atmospheric corrosion

In the present paper, the formation of protective coatings on the MA8 magnesium alloy by plasma electrolytic oxidation (PEO) with subsequent treatment of fluoropolymer is considered. The morphology of coatings after accelerated climatic tests was investigated and the elemental composition of coatings was studied after tests in a salt spray chamber (SSC). The analysis of the obtained results demonstrated a higher corrosion resistance of the fluoropolymer-containing layers in comparison with the base PEO coating

Formation of composite coatings: morphology and composition studies

In this work, composite fluoropolymer-containing coatings were obtained on samples of AMg3 aluminium alloy, MA8 magnesium alloy, and VT1-0 commercially pure titanium treated by plasma electrolytic oxidation (PEO). Superdispersed polytetrafluoroethylene (SPTFE) and a solution of tetrafluoroethylene (TFE) telomers in acetone were applied onto preliminarily formed PEO layers by the spray-coating method. The obtained coatings contained a large amount of crystalline polytetrafluoroethylene embedded in the outer porous layer of the PEO coating and did not have visible defects, which indirectly indicates high protective properties

Multifunctional polymer-containing coatings on magnesium alloys

The results of surface modification of magnesium alloys by plasma electrolytic oxidation (PEO) and post-treatment in suspension of tetrafluoroethylene (TFE) telomeric solution or superdispersed polytetrafluoroethylene (SPTFE) dispersion have been presented. Electrochemical, tribological properties and wetting ability of obtained protective composite coatings were investigated. The fabricated coatings decrease both the corrosion current density (1.7×10-9–5.4×10-11 A/cm2) and wear (9.8×10-6–7.6×10-7 mm3/(N m)) by orders of magnitude as compared to bare magnesium alloy (5.3×10-5 A/cm2 and 3.8×10-3 mm3/(N m)) and base PEO-coating (2.4×10-7 A/cm2 and 1.7×1-3 mm3/(N m)). Moreover, coatings obtained by means of PEO and polymer dispersion dipping possess hydrophobic and superhydrophobic properties. Such multifunctional coatings have high corrosion resistance and good friction coefficient under dry wear conditions that extends the application field of magnesium alloys

Formation and properties of composite nanostructured PEO-coatings on metals and alloys

Results of investigation of the incorporation of zirconia and titanium nitride nanoparticles into the coatings formed on magnesium alloy by plasma electrolytic oxidation are presented. Comprehensive research of electrochemical and mechanical properties of obtained coatings was carried out. It was established that the polarization resistance of the samples with a coating containing zirconia nanoparticles is in two fold higher than for the sample with base PEO-coating. One of the important reasons for improving the protective properties of coatings formed in electrolytes containing nanoparticles consists in enhanced morphological characteristics, in particular, the porosity decrease and increase of thickness and resistivity of porousless sublayer in comparison with base PEO-layer. Incorporation of zirconia and titanium nitride particles into the coating increases the mechanical performances. The coating containing nanoparticles have greater hardness and are more wear resistant in comparison with the coatings formed in the electrolyte without nanoparticle

Porous magnesium scaffolds with biodegradable polycaprolactone coating

The results of the synthesis of magnesium matrices with a porous structure have been presented. The cavities sizes vary from 10 microns to hundreds of microns. It has been obtained porous magnesium samples coated by spin-coating with biodegradable polycaprolactone. It has been shown that a dense layer of biodegradable polymer more than 50 μm thickness can be formed on the sample surface. Study of the electrochemical properties of the obtained coatings has been carried out. Obtained results suggest that porous magnesium metals with protective coatings can be used as degradable bone substitute implants

Porous magnesium scaffolds with biodegradable polycaprolactone coating

The results of the synthesis of magnesium matrices with a porous structure have been presented. The cavities sizes vary from 10 microns to hundreds of microns. It has been obtained porous magnesium samples coated by spin-coating with biodegradable polycaprolactone. It has been shown that a dense layer of biodegradable polymer more than 50 μm thickness can be formed on the sample surface. Study of the electrochemical properties of the obtained coatings has been carried out. Obtained results suggest that porous magnesium metals with protective coatings can be used as degradable bone substitute implants

Formation and properties of composite nanostructured PEO-coatings on metals and alloys

Results of investigation of the incorporation of zirconia and titanium nitride nanoparticles into the coatings formed on magnesium alloy by plasma electrolytic oxidation are presented. Comprehensive research of electrochemical and mechanical properties of obtained coatings was carried out. It was established that the polarization resistance of the samples with a coating containing zirconia nanoparticles is in two fold higher than for the sample with base PEO-coating. One of the important reasons for improving the protective properties of coatings formed in electrolytes containing nanoparticles consists in enhanced morphological characteristics, in particular, the porosity decrease and increase of thickness and resistivity of porousless sublayer in comparison with base PEO-layer. Incorporation of zirconia and titanium nitride particles into the coating increases the mechanical performances. The coating containing nanoparticles have greater hardness and are more wear resistant in comparison with the coatings formed in the electrolyte without nanoparticle

Physicochemical studies of composite coatings during accelerated tests for atmospheric corrosion

In the present paper, the formation of protective coatings on the MA8 magnesium alloy by plasma electrolytic oxidation (PEO) with subsequent treatment of fluoropolymer is considered. The morphology of coatings after accelerated climatic tests was investigated and the elemental composition of coatings was studied after tests in a salt spray chamber (SSC). The analysis of the obtained results demonstrated a higher corrosion resistance of the fluoropolymer-containing layers in comparison with the base PEO coating