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This research has addressed a complete study of the bioactivity of bioactive glass coatings obtained by atmospheric plasma spraying. The coatings have been characterized in terms of microstructure, adhesion, crystalline phases and bioactivity. Hydroxycarbonate apatite formation was also monitored following a standard protocol and the in vitro cell response was evaluated by human osteoblast-like cells (MG-63 cells) incubation. The obtained coatings shown a microstructure typical of glass coatings. A simulated body fluid test proved that coatings are capable of developing a surface layer of hydroxycarbonate apatite whereas the appearance of this phase takes place at a longer time than that observed for the powder feedstock. Cell-culture test showed multidirectional growth of MG-63 cells which promoted good contact between cells and the surface of the coating. This study has confirmed a positive effect of the coatings in terms of surface bioactivity and, more interestingly, it has proven an adequate cell-material interaction on the coating surface. Este trabajo ha abordado un estudio completo de la bioactividad de recubrimientos de vidrio bioactivo depositados mediante proyección térmica por plasma atmosférico. Se han caracterizado la microestructura, la adherencia, las fases cristalinas y la bioactividad de los recubrimientos obtenidos. También se ha estudiado la formación de hidroxiapatita carbonatada siguiendo un protocolo estándar y se ha evaluado la respuesta in vitro de los recubrimientos mediante su incubación con osteoblastos humanos (células MG-63). Los recubrimientos obtenidos han mostrado una microestructura típica de recubrimientos de vidrio. Tras la inmersión en fluido biológico simulado, se ha comprobado que el recubrimiento es capaz de desarrollar una capa superficial de hidroxiapatita carbonatada, aunque la velocidad de aparición de esta capa es menor que la observada para el polvo de vidrio de partida. El ensayo de cultivo celular ha mostrado un crecimiento multidireccional de las células MG-63, dando lugar a un buen contacto entre las células y la superficie del recubrimiento. Este estudio ha confirmado un efecto positivo de los recubrimientos en términos de bioactividad de la superficie y, lo que es más interesante, ha demostrado una adecuada interacción célula-material sobre la superficie del recubrimiento.

This research has addressed a complete study of the bioactivity of bioactive glass coatings obtained by atmospheric plasma spraying. The coatings have been characterized in terms of microstructure, adhesion, crystalline phases and bioactivity. Hydroxycarbonate apatite formation was also monitored following a standard protocol and the in vitro cell response was evaluated by human osteoblast-like cells (MG-63 cells) incubation. The obtained coatings shown a microstructure typical of glass coatings. A simulated body fluid test proved that coatings are capable of developing a surface layer of hydroxycarbonate apatite whereas the appearance of this phase takes place at a longer time than that observed for the powder feedstock. Cell-culture test showed multidirectional growth of MG-63 cells which promoted good contact between cells and the surface of the coating. This study has confirmed a positive effect of the coatings in terms of surface bioactivity and, more interestingly, it has proven an adequate cell-material interaction on the coating surface. Este trabajo ha abordado un estudio completo de la bioactividad de recubrimientos de vidrio bioactivo depositados mediante proyección térmica por plasma atmosférico. Se han caracterizado la microestructura, la adherencia, las fases cristalinas y la bioactividad de los recubrimientos obtenidos. También se ha estudiado la formación de hidroxiapatita carbonatada siguiendo un protocolo estándar y se ha evaluado la respuesta in vitro de los recubrimientos mediante su incubación con osteoblastos humanos (células MG-63). Los recubrimientos obtenidos han mostrado una microestructura típica de recubrimientos de vidrio. Tras la inmersión en fluido biológico simulado, se ha comprobado que el recubrimiento es capaz de desarrollar una capa superficial de hidroxiapatita carbonatada, aunque la velocidad de aparición de esta capa es menor que la observada para el polvo de vidrio de partida. El ensayo de cultivo celular ha mostrado un crecimiento multidireccional de las células MG-63, dando lugar a un buen contacto entre las células y la superficie del recubrimiento. Este estudio ha confirmado un efecto positivo de los recubrimientos en términos de bioactividad de la superficie y, lo que es más interesante, ha demostrado una adecuada interacción célula-material sobre la superficie del recubrimiento.

In this work a novel bioactive glass composition was used to deposit coatings by means of plasma spraying. Different coatings were manufactured and optimized by varying the processing parameters and were studied by X-ray diffraction and scanning electron microscopy. Moreover, the bioactivity was assessed by in vitro tests in Simulated Body Fluid solution. The coatings displayed the typical microstructure of atmospheric plasma sprayed coatings, that is a coating made up by the stacking of melted splats, with different thicknesses, porosities and crystalline phases depending on the spraying parameters used. The work showed that all the coatings are denser and with less porosity than those observed for plasma sprayed coatings of the well-known 45S5 bioactive glass, with similar particle size deposited under the same spraying conditions. The in vitro tests demonstrated the bioactive aptitude of all the coatings, on whose surface an hydroxycarbonate apatite layer formed after 7 days of soaking.

Diseases or complications that are caused by bone tissue damage affect millions of patients every year. Orthopedic and dental implants have become important treatment options for replacing and repairing missing or damaged parts of bones and teeth. In order to use a material in the manufacture of implants, the material must meet several requirements, such as mechanical stability, elasticity, biocompatibility, hydrophilicity, corrosion resistance, and non-toxicity. In the 1970s, a biocompatible glassy material called bioactive glass was discovered. At a later time, several glass materials with similar properties were developed. This material has a big potential to be used in formulating medical devices, but its fragility is an important disadvantage. The use of bioactive glasses in the form of coatings on metal substrates allows the combination of the mechanical hardness of the metal and the biocompatibility of the bioactive glass. In this review, an extensive study of the literature was conducted regarding the preparation methods of bioactive glass and the different techniques of coating on various substrates, such as stainless steel, titanium, and their alloys. Furthermore, the main doping agents that can be used to impart special properties to the bioactive glass coatings are described.

This work reports on the unprecedented magnetron sputtering deposition of submicrometric hollow cones of bioactive glass at low temperature in the absence of any template or catalyst. The influence of sputtering conditions on the formation and development of bioglass cones was studied. It was shown that larger populations of well-developed cones could be achieved by increasing the argon sputtering pressure. A mechanism describing the growth of bioglass hollow cones is presented, offering the links for process control and reproducibility of the cone features. The composition, structure, and morphology of the as-synthesized hollow cones were investigated by energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), grazing incidence geometry X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)-selected area electron diffraction (SAED). The in vitro biological performance, assessed by degradation tests (ISO 10993-14) and cytocompatibility assays (ISO 10993-5) in endothelial cell cultures, was excellent. This allied with resorbability and the unique morphological features make the submicrometer hollow cones interesting candidate material devices for focal transitory permeabilization of the blood-brain barrier in the treatment of carcinoma and neurodegenerative disorders.

This research addresses a simple and easy method to improve the microstructure of suspension plasma sprayed bioactive glass coatings. Based on previous research of the group, a SPS bioactive glass coating was deposited under optimised variables employing a stable suspension feedstock. After the microstructural characterisation, the coatings were subjected to a heat treatment at 400, 500 and 600 ºC peak temperatures. These temperatures have been chosen according to the shrinkage curve of the working glass which results from a hot stage microscope. Results show an improvement of the coatings microstructure (reduction in both porosity and thickness and increment of the adhesion) after a heat treatment at 500 ºC with respect to the original coating. However, for a temperature of 400 ºC the coating microstructure is not altered (porosity, thickness and adherence are the same as those of the original sample) while at 600 ºC the entire coating is completely delaminated.

Bioactive glasses are osteoproductive-type inorganic materials possessing the highest indices of bioactivity in both bulk and thin film forms. The prerequisites for reliable implant-type coatings are both their biological and mechanical performances. Whilst the bioglass films' structural, chemical and biological properties have been studied extensively, information about their mechanical performance is scarce. Here, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, nanoindentation and pull-out measurements were employed to assess the morphological, chemical, structural and mechanical properties of the bioglass films deposited onto Ti substrates by radio-frequency magnetron sputtering (RF-MS). The biological safety of the thin bioglass films was evaluated preliminarily in vitro by investigating the adherence, proliferation and cytotoxicity of fibroblast cells cultivated on their surface. Our study emphasize the versatility of RF-MS, showing how bioglass films' features such as composition, structure, bonding strength, hardness, elastic modulus and biological response can be conveniently adapted by tuning the RF-MS working conditions, and therefore demonstrating the unexplored potential of this deposition technique for preparing quality biomimetic glass coatings. (C) 2013 Elsevier B. V. All rights reserved.

Bioactive glasses are currently considered the suitable candidates to stir the quest for a new generation of osseous implants with superior biological/functional performance. In congruence with this vision, this contribution aims to introduce a reliable technological recipe for coating fairly complex 3D-shaped implants (e.g. dental screws) with uniform and mechanical resistant bioactive glass films by the radio-frequency magnetron sputtering method. The mechanical reliability of the bioactive glass films applied to real Ti dental implant fixtures has been evaluated by a procedure comprised of \"cold\" implantation in pig mandibular bone from a dead animal, followed by immediate tension-free extraction tests. The effects of the complex mechanical strains occurring during implantation were analysed by scanning electron microscopy coupled with electron dispersive spectroscopy. Extensive biocompatibility assays (MTS, immunofluorescence, Western blot) revealed that the bioactive glass films stimulated strong cellular adhesion and proliferation of human dental pulp stem cells, without promoting their differentiation. The ability of the implant coatings to conserve a healthy stem cell pool is promising to further endorse the fabrication of new osseointegration implant designs with extended lifetime. (C) 2015 Elsevier Ltd. All rights reserved.

45S5 bioactive glass powders with the composition of 45 SiO2, 6 P2O5, 24.5 CaO and 24.5 wt% Na2O were melted and quenched in water to obtain a frit. The frit was milled using two different routes: dry milling followed by sieving to obtain glass particles and wet milling followed by spray drying to obtain a powder comprising porous agglomerates. All feedstocks showed adequate characteristics that make them suitable to be deposited by atmospheric plasma spraying. The powders and coatings were characterised by field-emission gun environmental scanning electron microscope and X-ray diffraction. The roughness and the contact angle of the coatings were also determined. The bioactivity of the powders and coatings was assessed by immersion in simulated body fluid. It was found that bioactive glass prepared from bioglass frit by dry milling exhibited similar bioactivity as that of a commercial bioactive glass. All coatings produced showed good adhesion to the substrate as well as suitable surface properties to ensure efficient contact with body fluid. Regardless of the characteristics of the feedstocks or plasma spray conditions used, all coatings were exclusively made up of an amorphous phase. On the other hand, micrographs revealed that the characteristics of the feedstock strongly impact on the final coating microstructure. The most homogeneous microstructure was obtained when the feedstock was prepared by fine dry grinding of the frit. For this coating, the formation of a bioactive layer was also proved by Fourier transform infrared spectroscopy and X-ray diffraction.

The high-velocity suspension flame spraying technique (HVSFS) was employed in order to deposit 45S5 bioactive glass coatings onto titanium substrates, using a suspension of micron-sized glass powders dispersed in a water + isopropanol mixture as feedstock. By modifying the process parameters, five coatings with different thickness and porosity were obtained. The coatings were entirely glassy but exhibited a through-thickness microstructural gradient, as the deposition mechanisms of the glass droplets changed at every torch cycle because of the increase in the system temperature during spraying. After soaking in simulated body fluid, all of the coatings were soon covered by a layer of hydroxyapatite; furthermore, the coatings exhibited no cytotoxicity and human osteosarcoma cells could adhere and proliferate well onto their surfaces. HVSFS-deposited 45S5 bioglass coatings are therefore highly bioactive and have potentials as replacement of conventional hydroxyapatite in order to favour osseointegration of dental and prosthetic implants.