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A letter to the editor is presented concerning a study which examines mesenchymal stem cells (MSCs)-derived exosomes as treatment for refractory graft-versus-host disease (GvHD).

Regularities of the formation of calcium phosphate coatings on the surface of titanium and zirconium alloys formed by the method of microarc oxidation are investigated. The scheme of deposition of the calcium phosphate coating in microarc discharges is suggested that explains the difference in the morphology, microstructure, and properties of coatings on the surface of titanium and zirconium alloys. It is demonstrated that coatings on the surface of titanium and zirconium alloys have different structures, phase compositions, and physicomechanical properties due to different electrophysical characteristics of metal (titanium and zirconium) substrates, disperse β-Nb particles, and passivating oxide films on their surfaces. [ABSTRACT FROM AUTHOR]

Results of an experimental study of the optical characteristics of gas discharges are presented. The study was aimed at optimizing the operating modes of a mid-frequency magnetron sputtering system to efficiently deposit Ti-O-N coatings. The conditions for maintaining the intensity of the chosen spectroscopic lines that ensure synthesis of titanium oxide and titanium oxynitride coatings have been revealed. The morphology, structure, contact angle, and free surface energy of titanium oxide and titanium oxynitride coatings on type 12Kh18N10T stainless steel substrates were examined by using scanning and transmission electron microscopy and infrared spectroscopy, and by measuring the wetting angle. The results of examination of the structure and properties of the synthesized films and their physicomechanical and optical characteristics are given. [ABSTRACT FROM AUTHOR]

Using the methods of electron and atomic force microscopy, X-ray structural analysis and measurements of the wetting angle, the features of morphology, structure, contact angle and free surface energy of silicon-containing calcium-phosphate coatings formed on the substrates made from titanium VT1-0 and stainless steel 12Cr18Ni10Ti are investigated. It is shown that the coating - substrate system possesses bimodal roughness formed by the substrate microrelief and coating nanostructure, whose principal crystalline phase is represented by silicon-substituted hydroxiapatite with the size of the coherent scattering region (CSR) 18-26 nm. It is found out that the formation of a nanostructured coating on the surface of rough substrates makes them hydrophilic. The limiting angle of water wetting for the coatings formed on titanium and steel acquires the values in the following ranges: 90-92 and 101-104°, respectively, and decreases with time. [ABSTRACT FROM AUTHOR]

The potential of x-ray powder diffraction to analyze the size and ultrastructure of metallic nanoparticles (silver, gold, silver-gold alloy, and calcium phosphate) is demonstrated. By the Rietveld analysis, it is possible to estimate the crystallite size for such nanoparticles, even if they are very small (4 nm), using the effect of peak broadening in small crystallites. The results correspond well to crystallite size as determined by transmission electron microscopy (TEM), also confirming the twinned nature of the metallic nanoparticles. For calcium phosphate nanorods which are not twinned, the results by x-ray powder diffraction and TEM are in good agreement. [ABSTRACT FROM AUTHOR]

Results are presented of studies of the physical-mechanical properties of silver-doped calcium phosphate coatings formed by radio-frequency magnetron sputtering on a surface of technically pure VT1-0 titanium and 12Cr18Ni10Ti stainless chromium-nickel surgical steel. The films have the nanocrystalline structure of hydroxyapatite with mean diameter of the coherently diffracting domains equal to 20-30 nm. It has been established that the configuration of the magnetic field of the magnetron has an effect on the roughness, thickness, and refractive index of the coatings. The thickness of the coatings and the refractive index vary within the ranges 300-700 nm and 1.68-1.80, respectively. The nanohardness of the coatings is within the range 4-7GPa, the modulus of elasticity of the coatings depends on the material of the substrate and is equal to 130-150 GPa for titanium and 170-200 GPa for steel. Sclerometric measurements of the coatings made it possible to establish a high adhesion strength of the coatings. [ABSTRACT FROM AUTHOR]

Silicon-containing hydroxyapatite coatings 400-700 nm in thickness are prepared by means of radio-frequency (RF) magnetron sputtering on a heated (to 200°C) titanium substrate chemically etched and treated with a pulsed electron beam. The morphology and phase composition of the coating are studied. The morphology and roughness of the composite 'calcium-phosphate coating-titanium substrate' differ depending on the treatment procedure of the substrate before deposition. The scratch test method is used to assess the adhesion strength of the coatings formed at different values of bias potential applied to the substrate. It is observed that the adhesion strength of the coating changes with decreasing crystallite size. [ABSTRACT FROM AUTHOR]

We studied by X-ray diffraction analysis, IR spectroscopy, and scanning electron microscopy (SEM) the phase composition and the structure of coatings based on silicon-containing hydroxyapatite (Si-HA) deposited by RF-magnetron sputtering. The sputtering target contained two phases (apatite and tricalcium phosphate) and was produced by the ceramic technology from a single-phase mechanically activated powder precursor. The structure of the coating deposited by sputtering from the two-phase target was single phase (hydroxyapatite) and textured in the (002) direction. During deposition, silicate anions partially replaced phosphate ions in the apatite lattice. [ABSTRACT FROM AUTHOR]

Silicon-containing calcium phosphate (Si-CaP) coatings on titanium and austenite steel substrates have been prepared by method of high-frequency magnetron sputtering. The powder of silicon-containing hydroxyapatite Ca(PO)(SiO)(HO) (Si-HA), where x = 0.5 obtained using a mechanochemical technique, was used as a target material. The obtained coatings were X-ray amorphous; the elemental composition of the coatings depended on the composition of the target to be sputtered. The coatings were heated in air for 3 hours to the temperature 700°C with the aim of changing their structure. The bioactivity of the coatings was studied using in-vitro tests. The solution of the simulated body fluid (SBF) oversaturated with respect to HA was used as a model medium. The phase elemental composition and morphology of the deposited and annealed Si-CaP coatings before and after submersion into the solution were controlled using the methods of X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDAX), and scanning electron microscopy (SEM). According to the XFA and IR-spectroscopy data, heat treatment in the air yields the formation of an apatite-like phase in the coating. Thermostating of 'metal + coating' specimens in the solution of simulated body fluid revealed that all obtained coatings were biologically active, and a calcium phosphate layer was formed on the coating surface during mineralization. The annealed coatings show a higher chemical stability under physiological conditions as compared to amorphous coatings. [ABSTRACT FROM AUTHOR]

Abstract: Biodegradable calcium phosphate nanoparticles as carriers for the immunoactive toll-like receptor ligands CpG and polyinosinic–polycytidylic acid for the activation of dendritic cells (DC) combined with the viral antigen hemagglutinin (HA) were prepared. A purification method based on ultracentrifugation and ultrasonication was developed to separate the nanoparticles from dissolved biomolecules. The number of biomolecules, i.e., oligonucleotides and peptide, incorporated into the nanoparticles was quantitatively determined by UV-spectroscopy, using fluorescent derivatives of the biomolecules. The immunostimulatory effects of purified calcium phosphate nanoparticles on DC were studied, i.e., cytokine production and activation of the cells in terms of the upregulation of surface molecules. Purified calcium phosphate nanoparticles, i.e., without dissolved biomolecules, are capable of inducing adaptive immunity by activation of DC. Immunostimulatory effects of purified calcium phosphate nanoparticles on DC were demonstrated by increased expression of co-stimulatory molecules and MHC II and by cytokine secretion. In addition, DC treated with purified functionalized calcium phosphate nanoparticles induced an antigen-specific T-cell response in vitro. [Copyright &y& Elsevier]

Coatings based on pure silicon and silicon-substituted hydroxyapatite were grown by RF magnetron sputtering. The coating surface morphology, phase and elemental composition were studied by scanning electron microscopy, energy-dispersive X-ray analysis, and infrared spectroscopy. It was found that coatings are X-ray-amorphous, their elemental composition being controlled by the sputtered target composition. The distribution of elements over the coating surface is homogeneous. Medical and biological properties of coatings were studied in vivo and in vitro. Osteogenic properties of coatings were studied. Coatings grown by sputtering of a stoichiometric hydroxyapatite target are biocompatible without osteoinductive activity. The introduction of silicate ions into the hydroxyapatite structure that forms an electrode target significantly enhances the in vivo effect of CaP magnetron coatings on the osteogenic activity and stromal bone-marrow stem cells. [ABSTRACT FROM AUTHOR]

Abstract: Silver nanoparticles (Ag-NP) are increasingly used in biomedical applications because of their remarkable antimicrobial activity. In biomedicine, Ag-NP are coated onto or embedded in wound dressings, surgical instruments and bone substitute biomaterials, such as silver-containing calcium phosphate cements. Free Ag-NP and silver ions are released from these coatings or after the degradation of a biomaterial, and may come into close contact with blood cells. Despite the widespread use of Ag-NP as an antimicrobial agent, there is a serious lack of information on the biological effects of Ag-NP on human blood cells. In this study, the uptake of Ag-NP by peripheral monocytes and lymphocytes (T-cells) was analyzed, and the influence of nanosilver on cell biological functions (proliferation, the expression of adhesion molecules, cytokine release and the generation of reactive oxygen species) was studied. After cell culture in the presence of monodispersed Ag-NP (5–30μgml−1 silver concentration), agglomerates of nanoparticles were detected within monocytes (CD14+) but not in T-cells (CD3+) by light microscopy, flow cytometry and combined focused ion beam/scanning electron microscopy. The uptake rate of nanoparticles was concentration dependent, and the silver agglomerates were typically found in the cytoplasm. Furthermore, a concentration-dependent activation (e.g. an increased expression of adhesion molecule CD54) of monocytes at Ag-NP concentrations of 10–15μgml−1 was observed, and cytotoxicity of Ag-NP-treated monocytes was observed at Ag-NP levels of 25μgml−1 and higher. However, no modulation of T-cell proliferation was observed in the presence of Ag-NP. Taken together, our results provide the first evidence for a cell-type-specific uptake of Ag-NP by peripheral blood mononuclear cells (PBMC) and the resultant cellular responses after exposure. [Copyright &y& Elsevier]

The rhopalia and statocysts of Periphylla periphylla (Péron and Lesueur in Ann Mus Hist Nat Marseille 14:316-366,) and Chironex fleckeri Southcott (Aust J Mar Freshw Res 7(2):254-280 ) were examined histologically and showed several homologous characteristics. Differences in sensory area distribution could be connected to a slightly different functionality of equilibrium sensing. In P. periphylla, the statoliths (crystals) grow independently of each other; whereas in C. fleckeri, one large crystal covers the smaller ones. The structures of both statoliths were examined in detail with single-crystal diffraction, microtomography and diffraction contrast tomography. The single compact statolith of C. fleckeri consisted of bassanite as was previously known only for other rhopaliophoran medusae. An origin area with several small oligocrystals was located in the centre of the cubozoan statolith. The origin areas and the accretion of statoliths are similar in both species. Our results lead to the assumption that the single bassanite statolith of C. fleckeri (Cnidaria, Cubozoa) is a progression of the scyphozoan multiplex statolith. It is therefore suggested that the Cubozoa are derived from a scyphozoan ancestor and are a highly developed taxa within the Rhopaliophora. [ABSTRACT FROM AUTHOR]

Abstract: Silver nanoparticles (Ag-NP) are widely used due to their well-known antibacterial effects. In medicine Ag-NP have found applications as wound dressings, surgical instruments and bone substitute biomaterials, e.g. silver-containing calcium phosphate cements. Depending on the coating technique, during resorption of a biomaterial Ag-NP may come into close contact with body tissues, including human mesenchymal stem cells (hMSC). Despite the widespread uses of Ag-NP, there is a serious lack of information concerning their biological effects on human cells. In this study the uptake of Ag-NP into hMSC has been analyzed and the intracellular distribution of Ag-NP after exposure determined. Non-agglomerated (dispersed) Ag-NP from the cell culture medium were detected as agglomerates of nanoparticles within the hMSC by combined focused ion beam/scanning electron microscopy. The silver agglomerates were typically located in the perinuclear region, as determined by light microscopy. Specific staining of cellular structures (endo-lysosomes, nuclei, Golgi complex and endoplasmatic reticulum) using fluorescent probes showed that the silver nanoparticles occurred mainly within endo-lysosomal structures, not in the cell nucleus, endoplasmic reticulum or Golgi complex. Quantitative determination of the uptake of Ag-NP by flow cytometry (scattergram analysis) revealed a concentration-dependent uptake of the particles which was significantly inhibited by chlorpromazine and wortmannin but not by nystatin, indicating clathrin-dependent endocytosis and macropinocytosis as the primary uptake mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline calcium phosphates containing carbonate have a high similarity to bone mineral. The reactions of bone cells (primary osteoblasts and osteoclast-like cells) on these materials as well as on sintered β-tricalcium phosphate and hydroxyapatite (HA) confirmed a good biocompatibility of the nanocrystalline samples. However, osteoclastic differentiation was constrained on the carbonate-rich samples, leading to a small number of osteoclast-like cells on the materials and few resorption pits. The grain size of the calcium phosphate ceramics (nano vs. micro) was less important than expected from to physico-chemical considerations. When comparing the nanocrystalline samples, the highest resorption rate was found for nano-HA with a low carbonate content, which strongly stimulated the differentiation of osteoclast-like cells on its surface. [Copyright &y& Elsevier]

The charge of nanoparticles influences their ability to pass through the cellular membrane, and a positive charge should be beneficial. The negative charge of calcium phosphate nanoparticles with an inner shell of carboxymethyl cellulose (CMC) was reversed by adding an outer shell of poly(ethyleneimine) (PEI) into which the photoactive dye 5,10,15,20-tetrakis(3-hydroxyphenyl)-porphyrin ( mTHPP) was loaded. The aqueous dispersion of the nanoparticles was used for photodynamic therapy with HT29 cells (human colon adenocarcinoma cells), HIG-82 cells (rabbit synoviocytes), and J774A.1 cells (murine macrophages). A high photodynamic activity (killing) together with a very low dark toxicity was observed for HIG-82 and for J774.1 cells at 2 μM dye concentration. The killing efficiency was equivalent to the pure photoactive dye that, however, needs to be administered in alcoholic solution. [ABSTRACT FROM AUTHOR]

Fourteen different synthetic or biological bone substitution materials were characterised by high-resolution X-ray diffractometry, infrared spectroscopy, thermogravimetry, and scanning electron microscopy. Thus, the main parameters chemical composition, crystallinity, and morphology were determined. The results are compared with natural bone samples. The materials fall into different classes: Chemically treated bone, calcined bovine bone, algae-derived hydroxyapatite, synthetic hydroxyapatite, peptide-loaded hydroxyapatite, and synthetic β-TCP ceramics. [Copyright &y& Elsevier]

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Halogenoacetates are known to undergo a solid-state elimination reaction to metal halide and poly(hydroxyacetic acid), polyglycolide. Earlier studies have shown that the reaction takes place exclusively in the solid-state without the occurrence of liquid intermediates. Single crystals of sodium chloroacetate and silver chloroacetate were reacted and studied with X-ray diffractometry, scanning electron microscopy and thermomicroscopy. The results show that the reaction leads from single crystals to a composite of polyglycolide and metal halide. Neither the salt nor the polymer exhibit a preferred crystallographic orientation, therefore it must be concluded that the crystal lattice is not preserved during the reaction. [ABSTRACT FROM AUTHOR]

Abstract Structural properties of hydrogen- and water-intercalated superconductors YBa Cu O are discussed on the basis of new high-resolution electron 2 3 7 microscopy, electron diffraction, X-ray diffraction, extended X-ray absorption fine structure (EXAFS) and Raman measurements. The multistep intercalation reaction proceeding at temperatures below 200oC leads to significant changes in the crystal structure via shear transformation resulting in a highly crystalline end phase. A new structure model was proposed for H YBa Cu O which includes 2 2 3 8 Cu-O single chains as in YBa Cu O . This result differs in principle from all 2 3 7 models proposed before. [ABSTRACT FROM AUTHOR]