Bioglass Coatings Research Articles

Applying 58S Bioglass Coating on Titanium Substrate: Effect of Multiscale Roughness on Bioactivity, Corrosion Resistance and Coating Adhesion

Applying 58S Bioglass Coating on Titanium Substrate: Effect of Multiscale Roughness on Bioactivity, Corrosion Resistance and Coating Adhesion

The Effect of Bioglass Coating on Microshear Bond Strength of Resin Cement to Zirconia.

Objectives: Durable bonding to zirconia is a challenging issue in dentistry. This study aimed to assess the effect of bioglass coating of zirconia on the microshear bond strength of resin cement to zirconia and to study the effect of thermocycling on this bond. Materials and Methods: This in-vitro experimental study was conducted on 60 yttria-stabilized tetragonal zirconia blocks in six groups (N=10) based on surface pretreatment and thermocycling. Surface pretreatments included no treatment control, alumina particle abrasion, and bioglass-coating of zirconia. Resin bonding was performed with Panavia F2.0 cements. Then, half of the specimens underwent a 24-hour incubation in 37°C water, while the other half were subjected to thermocycling (12000 cycles, 5-55°C, 60s for each batch) following the same incubation period. Subsequently, the microshear bond strength of the specimens was measured. Additionally, one block from each group was subjected to scanning electron microscopy and X-ray diffraction. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. Results: There was a significant difference between the bond strength values of different groups (P<0.001). Alumina particle abrasion and bioglass coating equally increased the bond strength compared to the untreated control group (P<0.001). Thermocycling caused significant decreases in bond strength in all the groups (P<0.001); however, the bond strength value of the thermocycled bioglass-coated group was significantly higher than that reported for the thermocycled alumina particle abraded group (P=0.015). Conclusion: Despite the decrease in the bond strength values after thermocycling, the long-term efficacy of the bioglass coating of zirconia was promising.

The Effect of Silver and Samarium on the Properties of Bioglass Coatings Produced by Pulsed Laser Deposition and Spin Coating.

The current study reports the use of silver (Ag) and samarium (Sm) as dopants to improve the properties of standard bioglass in terms of biological performance. This experiment considers thin films of doped bioglass obtained by pulsed laser deposition (PLD) and spin coating (SC). For both methods, some parameters were gradually varied, as the main objective was to produce a bioglass that could be used in biomedical fields. In order to study the morphology, the phase composition and other properties, the samples obtained were subjected to multiple analyses, such as thermal analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared (FT-IR), Raman spectroscopy, and x-ray diffraction (XRD). Furthermore, the in vitro bioactivity of the samples, as assessed through simulated body fluid (SBF) immersion, as well as immunocytochemistry and evaluation of actin filaments, assessed through fluorescence microscopy, are reported. The results confirmed the formation of the designed vitreous target employed as the source of material in the PLD experiments only at sintering temperatures below 800 °C; this vitreous nature was preserved in the grown film as well. The presence of Ag and Ce dopants in the parent glassy matrix was validated for all stages, from powder, to target, to PLD/SC-derived coatings. Additionally, it was demonstrated that the surface topography of the layers can be adjusted by using substrates with different roughness or by modulating the processing parameters, such as substrate temperature and working pressure in PLD, rotation speed, and number of layers in SC. The developed material was found to be highly bioactive after 28 days of immersion in SBF, but it was also found to be a potential candidate for inhibiting the growth of Gram-negative bacteria and a suitable support for cell growth and proliferation.

Complex Bioactive Chitosan–Bioglass Coatings on a New Advanced TiTaZrAg Medium–High-Entropy Alloy

High-entropy alloys (HEAs), also known as multicomponent or multi-principal element alloys (MPEAs), differ from traditional alloys, which are usually based only on one principal element, in that they are usually fabricated from five or more elements in large percentages related to each other, in the range of 5%–35%. Despite the usually outstanding characteristics of HEAs, based on a properly selected design, many such alloys are coated with advanced composites after their elaboration to further improve their qualities. In this study, 73Ti-20Zr-5Ta-2Ag samples were covered with chitosan and a mixture of chitosan, bioglass, and ZnO particles to improve the materials’ antibacterial properties. A variety of methods, including scanning electron microscopy, atomic force microscopy, and mechanical and electrochemical determinations, has permitted a quantified comparison between the coated and uncoated surfaces of this medium–high-entropy alloy. The materials’ properties were enhanced by the complex coating, giving the alloys not only high antibacterial activity, but also good corrosion protection.

Biomechanical behavior of functionally graded S53P4 bioglass-zirconia dental implants: Experimental and finite element analyses

ObjectivesThe aim of this work was to evaluate the biomechanical behavior of one-piece zirconia implants with a functionally graded bioglass (BG) layer as compared to monolithic zirconia and BG-coated implants, using the finite element method (FEM). MethodsZirconia disks were infiltrated with bioglass S53P4 and then morphologically inspected by scanning electron microscopy (SEM) followed by mechanical analyses on micro-indentation tests for further biomechanical validation using the finite element method (FEM). On modeling, zirconia dental implants anchored into mandibular bone were simulated on occlusal loading as recorded under mastication. Three types of implants were simulated: i) free of BG coating, ii) with 100 μm or 150 μm thick conventional BG coatings; and iii) with graded BG coatings involving 3 different chemical composition distributions. The stress state at both implant and bone were evaluated using the FEM. The mechanically-induced bone remodelling was analyzed through the bone strain results. ResultsInfiltration of BG into a zirconia structure resulted in a ∼100 μm thick layer with an exponential-like gradation of chemical composition and properties. Regarding the FEM calculations, the BG coating induced up to 30% decrease on stress in the implant body when compared to the monolithic zirconia implant. The gradient of chemical composition also improved the stresses’ distribution. The stresses distribution towards the BG-coatings were significantly high and could lead to failure. Stresses on the bone were recorded down to its strength threshold, with insignificant influence of the coating layer. The bone strain values on all models indicates further bone remodelling although BG-coated and BG-graded zirconia implants showed the highest strain magnitude that may enhance the mechanical stimulation for bone maintenance. SignificanceGraded BG-zirconia dental implants showed enhanced overall biomechanical behaviour as compared to the BG-coated or monolithic zirconia dental implants. Also, such biomechanical improvements noticed for the BG-graded system should be considered in combination with the well-known osseointegration benefits of bioactive glasses.

Analysis ofin vitrocorrosion behavior and hemocompatibility of electrophoretically deposited bioglass–chitosan–iron oxide coating for biomedical applications

Abstract

Influence of Atmospheric Plasma Spraying Parameters on Porosity Formation in Coatings Manufactured from 45S5 Bioglass® powder

Atmospheric plasma spraying parameters were studied to understand their influence on the splat stacking and the porosity formation in coatings made from commercial Schott 45S5 Bioglass® powder onto AISI 304 L stainless steel substrate. The spraying parameters were established from numerical simulation carried out by the Jets&Poudres software. The plasma spraying was performed by using an Oerlikon Metco F4 MB gun with a 6-mm-internal-diameter nozzle. Three Ar/H2 mixtures were used as plasma-forming gas (95/5, 88/12 and 84/16 vol.%), and the current intensity was varied from 450 to 650 A and the spray distance from 60 to 100 mm. The cooling of the samples during spraying was controlled by air jet pressure. The x-ray diffraction and the scanning electron microscopy were used to determine phases and structural characteristics of coatings, respectively. The numerical simulation results for each set of spray parameters have shown suitable Sommerfeld number for proper splat stacking. However, Na2O and P2O5 evaporation occurred experimentally during spraying of 45S5 Bioglass® promoted the porosity formation into the coating structure. Low porosity was obtained for 45S5 Bioglass coatings manufactured under the appropriate relationship between plasma-forming gas mixture ratio, current intensity, spray distance and cooling air jet pressure to achieve thermal energy input enough to overcome the glass transition temperature and to avoid the evaporation of volatile oxides.

Effect of processing on microstructure, mechanical properties and dissolution behaviour in SBF of Bioglass (45S5) coatings deposited by Suspension High Velocity Oxy Fuel (SHVOF) thermal spray

Bioglass (45S5) is known to react with physiological media and has the unique characteristic of bonding with hard and soft tissues when implanted in the body. 45S5 coatings were deposited by Suspension High Velocity Oxy Fuel (SHVOF) thermal spraying to investigate the effect of combustion conditions on the coating microstructure and surface topography. Bioactive (45S5) coatings were deposited onto 304 stainless steel substrates via SHVOF thermal spray using a water + isopropanol (IPA) based suspension with 8 wt% particle loading. Selected flame powers of 25 kW (low), 50 kW (medium) and 75 kW (high) produced three different coatings of varying microstructure (porosity and thickness) and composition. At 25 kW flame power thin coating of <10 μm thickness was deposited; however, 25 ± 3 μm thick, well bonded coatings to the substrates were deposited at flame powers of 50 and 75 kW. The medium flame power coating was 16 ± 2% porous, while the high flame power coating was 10 ± 1% porous. All the coatings remained amorphous, as confirmed via X-ray diffraction. After immersing the coated samples in simulated body fluid (SBF), 50 and 75 kW coatings revealed hydroxyapatite (HA) deposition after 3 days. Also, no HA deposition was observed on 25 kW coating, even after 7 days of immersion in SBF. EDX analysis of the 50 kW coating after 7 days immersion in SBF showed that the initial coating thickness reduced from 25 μm to 6 μm, it means that this microstructure was highly reactive towards SBF and hence behaved like a resorbable coating. Through SHVOF spraying technique changing the flame power resulted in coatings of varying microstructure. These microstructures behaved differently in SBF, 50 kW coating showed more degradation than the 75 kW coating owing to the porosity.

Approach for fabricating bioglass coatings on reticulated vitreous carbon foams for tissue engineering applications

Reticulated vitreous carbon foams have recently been used in the fabrication of scaffolds for biomedical applications, and have been shown to support cell adhesion. In this research, a methodology for coating reticulated vitreous carbon foams with two different bioglasses synthesized using the sol-gel technique is presented, towards enhancing the bioactivity of the reticulated vitreous carbon scaffolds. These coatings were morphologically characterized by confocal optical microscopy and scanning electron microscopy. Moreover, reactivity of the coated foams was also evaluated through in vitro tests by immersion in physiological solution. The results show successful deposition of the bioglass coating on the surface of the foams without compromising foam porosity. Coating morphological studies revealed a relationship between the composition of the bioglass and the final morphology of the coating. Additionally, preliminary in vitro tests showed that coating reactivity was also related to initial coating composition. Although the coatings dissolved after 21 days in PBS, the precipitation of a calcium-phosphate layer indicated the potential presence of the initial phases of the apatite formation process.

Electrophoretic deposition and laser cladding of bioglass coating on Ti

Abstract Bioglass coatings derived from electrophoretic deposition method were fused on Ti surface by laser cladding process using a continuous CO 2 laser. The specimens were studied by field-emission scanning electron microscopy, X-ray diffraction and bonding tests. Titanium oxide layer with hierarchical structures consisting of submicron rows of leaf-like embossments and nano-pores was obtained by combining acid etching and anodization processes, which increased the surface roughness of Ti. When heat-treatment temperature was 700 °C and high, CaSiO 3 phase began to crystallize from the bioglass matrix and the crystallinity reached its maximum at 700 °C. During the electrophoretic deposition process, porous bioglass coatings composed of bioglass particles and fibers were deposited on Ti surface. Bioglass coatings with similar hierarchical structure containing submillimeter bioglass beads and microfibers were synthesized on Ti surface by laser fusion. There are no obvious microcracks at the interface of the Ti-coating, which revealed the good bonding between Ti-porcelain. With the laser scanning distance decreased, the bond strength increased accordingly. After only one day immersion in SBF, calcium phosphate began to precipitate on the bioglass coatings' surfaces. The thickness of the calcium phosphate precipitation and the amount of microparticles increased with immersion time.

Hydroxyapatite coatings with oriented nanoplate and nanorod arrays: Fabrication, morphology, cytocompatibility and osteogenic differentiation

Hydroxyapatite (HA) crystals exhibit rod-like shape with c-axis orientation and plate-like shape with a(b)-axis orientation in vertebrate bones and tooth enamel surfaces, respectively. Herein, we report the synthesis of HA coatings with the oriented nanorod arrays (RHACs) and HA coatings with oriented nanoplate arrays (PHACs) by using bioglass coatings as sacrificial templates. After soaking in simulated body fluid (SBF) at 120°C, the bioglass coatings are hydrothermally converted into the HA coatings via a dissolution-precipitation reaction. If the Ca/P ratios in SBF are 2.50 and 1.25, the HA crystals on the coatings are oriented nanorod arrays and oriented nanoplate arrays, respectively. Moreover, the bioglass coatings are treated with SBF at 37°C, plate-like HA coatings with a low crystallinity (SHACs) are prepared. As compared with the Ti6Al4V and SHACs, the human bone marrow stromal cells (hBMSCs) on the RHACs and PHACs have better cell adhesion, spreading, proliferation and osteogenic differentiation because of their moderately hydrophilic surfaces and similar chemical composition, morphology and crystal orientation to human hard tissues. Notably, the morphologies of HA crystals have no obvious effects on cytocompatibility and osteogenic differentiation. Hence, the HA coatings with oriented nanoplate arrays or oriented nanorod arrays have a great potential for orthopedic applications.

Structural characterization and electrochemical behavior of 45S5 bioglass coating on Ti6Al4V alloy for dental applications

Abstract In the present work, 45S5 bioglass coatings were deposited on the Ti6Al4 V alloy substrate through the cathodic colloidal electrophoretic deposition process (CEDP) proposed in this work. The coatings were thermally treated at temperatures of 500, 600, 700, and 800 °C for 2 h, and their structure was characterized by FESEM and DRX. Nanostructure and phase evolution of the coatings and xerogels was followed as a function of temperature. The corrosion resistance of the Ti6Al4 V alloy and the 45S5/Ti6Al4 V coating was studied by means of Tafel extrapolation in Hank's solution, at 37 °C, simulating the conditions inside the mouth. The 45S5 bioglass coatings displayed an amorphous nanostructure at lower temperatures, and partial crystallization at higher temperatures. An increase in the corrosion resistance was observed in the 45S5/Ti6l4 V coating treated at 700 °C because it reduced the i corr , and there was a change in the E corr towards more noble values. A model of the chemical anchorage of the 45S5 bioglass coating on Ti6Al4 V was proposed.

Electron emission from the zirconium coated suspension plasma sprayed bioglass

The suspension plasma sprayed bioglass coatings were covered with electrically conducting zirconium film obtained by sputtering. The microstructure of the coatings, observed by scanning electron microscope (SEM) shows the spherical droplets and some acicular grains formed at the bioglass recrystallization. The coatings were submitted to the electron emission investigations. The measurements enabled to find out the critical electric field and electron emission coefficient. The values of the critical field as low as Eth=12V/μm and of the field enhancement coefficient being as high as β=280 are comparable to the values reached for carbon nanotubes. The possible application of the electron field emitting coatings is the large-area emission source used as e.g. information display.

Hydrothermal synthesis of hydroxyapatite coatings with oriented nanorod arrays

Hydroxyapatite coatings (HACs) with oriented nanorod arrays have been fabricated according to the following stages: (i) sol–gel preparation of bioglass coatings (BGCs) on Ti6Al4V substrates; and (ii) transformation of the BGCs to the HACs in a simulated body fluid (SBF) under hydrothermal conditions. After soaking the BGCs in SBF for 12 h under hydrothermal conditions, the elongated HA rods deposit on the surfaces via a dissolution–precipitation reaction. The TEM image and corresponding ED pattern indicate that the HA rods in the HACs are single crystals with a preferential (002) orientation. With increasing the reaction time to 2 days, most of the HA rods are converted to HA particles due to Ostwald ripening. If SBF is replaced by deionized water, the obtained coatings are rod-like HA with the poor crystal orientation. Beside the reaction time and reaction medium, the reaction conditions play an important role in the morphologies of the HACs. Although a HA layer deposits also on the BGCs after soaking in SBF at 37 °C, the HA crystals exhibit plate-like structure. SBF immersion tests and biocompatibility tests by using human bone marrow stromal cells (hBMSCs) as cell models indicate that the HACs with oriented nanorod arrays exhibit great in vitro bioactivity and biocompatibility. The oriented HA rods on the coatings can not only promote the formation of bone-like apatite, but also improve the adhesion, spreading and proliferation of hBMSCs. The excellent in vitro bioactivity and biocompatibility suggest that the HACs with oriented nanorod arrays have great potential for bone implants.

Magnetic hydroxyapatite coatings with oriented nanorod arrays: hydrothermal synthesis, structure and biocompatibility.

Ideal biocoatings for bone implants should be similar to the minerals of natural bones in chemical composition, crystallinity, and crystallographic texture. Herein, magnetic hydroxyapatite (HA) coatings (MHACs) with oriented nanorod arrays have been fabricated by using magnetic bioglass coatings (CaO-SiO2-P2O5-Fe3O4, MBGCs) as sacrificial templates. After the hydrothermal reaction for 24 h, the MBGCs are converted to MHACs in a simulated body fluid (SBF) via a dissolution-precipitation reaction. The formed HA nanorods with a preferential (002) orientation are perpendicular to the coating surfaces. The Fe3O4 nanoparticles in the coatings improve the nucleation rate of HA, so the elongated HA nanocrystals are retained even after hydrothermal reaction for 3 days. In contrast, if no magnetic nanoparticles are incorporated into the bioglass coatings (BGCs), the HA nanorods turn into blocky HA particles upon increasing the reaction time from 12 h to 24 h. Moreover, the MHACs possess much better hydrophilicity with a contact angle of 10.8° than the HA coatings because of the presence of Fe3O4 nanoparticles. The biocompatibility tests have been investigated by using human bone marrow stromal cells (hBMSCs) as cell models. The hBMSCs have better cell adhesion, spreading and proliferation on the MHACs than on the BGCs or MBGCs because of the HA phase, good hydrophilicity and oriented nanorod arrays. The excellent biocompatibility of the MHACs suggests that they have great potential for bone implants.

Bioactivation of 304 Stainless Steel Surface through 45S5 Bioglass Coating for Biomedical Applications

Bioactivation of 304 Stainless Steel Surface through 45S5 Bioglass Coating for Biomedical Applications

Microstructure and in vitro behaviour of 45S5 bioglass coatings deposited by high velocity suspension flame spraying (HVSFS)

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.

Osteoconductivity and growth factor production by MG63 osteoblastic cells on bioglass‐coated orthopedic implants

We have produced Bioglass coatings for Orthopedic implants by using a novel coating technique, CoBlast. The two resultant surfaces, designated BG and hydroxyapatite (HA)/BG, were compared with their HA counterpart, OsteoZip in terms of osteoblastic cell attachment, adhesion, proliferation, differentiation, and growth factor production. BG and HA/BG were demonstrated by goniometry to be more hydrophilic than OsteoZip. This corresponded to enhanced protein adsorption, cell attachment, and cell adhesion documented by both quantitative and qualitative assessments. BG and HA/BG surfaces had a significant initial release of Si and Ca ions, and this was consistent with elevated cell proliferation and basic fibroblast growth factor levels. However, OsteoZip, being similar to HA/BG, exhibited better osteogenic differentiation than BG did, shown by augmented differentiation marker activity at both protein and mRNA levels. Sandwich ELISA was used to quantify angiopoietin and inducible nitric oxide synthase which are involved in peri-prosthetic angiogenesis and aseptic loosening of total hip replacement, respectively. Both Bioglass-derived coatings provide superior initial osteoconductivity to OsteoZip, and HA/Bioglass composite coating outruns in long-term osteogenic differentiation and prognostic bioprocesses. The novel coatings discovered in this study have significant potential in providing both orthopedic and therapeutic functions.

Bioactive glass thin films deposited by magnetron sputtering technique: The role of working pressure

Bioglass coatings were prepared by radio frequency magnetron sputtering deposition at low temperature (150 °C) onto silicon substrates. The influence of argon pressure values used during deposition (0.2 Pa, 0.3 Pa and 0.4 Pa) on the short-range structure and biomineralization potential of the bioglass coatings was studied. The biomineralization capability was evaluated after 30 days of immersion in simulated body fluid. SEM-EDS, XRD and FTIR measurements were performed. The tests clearly showed strong biomineralization features for the bioglass films. The thickness of the chemically grown hydroxyapatite layers was more than twice greater for the BG films deposited at the highest working pressure, in comparison to those grown on the films obtained at lower working pressures. The paper attempts to explain this experimental fact based on structural and compositional considerations.

Characteristics of bioactive glass coatings obtained by pulsed laser deposition

AbstractA type of bioglass (named Mg10) formed by the substitution of 10wt%Na2O with MgO in Bioglass® 45S5 was designed and coated on the substrate Ti6Al4V by pulsed laser deposition (PLD) technique. Scratch test results show that the bonding strength of Mg10 coating with the substrate is higher than that of 45S5 coating. The reason is that the thermal expansion coefficient of Mg10 matches that of Ti6Al4V more than that of 45S5. The in vitro behavior of the Mg10 bioglass coatings is similar to that of 45S5 bioglass coatings and follows the bioactive mechanism. The bioactivity level of Mg10 coating is lower than that of 45S5 coating. This could be attributed to the addition of Mg in Mg10, as part of Mg ions in the bioglass become network former, which decreases the Si‐O‐NBO/Si‐O‐Si (s) intensity ratio of the Mg10 coating. Therefore, substitution of 10wt%Na2O with MgO on the base of Bioglass® 45S5 coatings can improve their long‐term stability while maintaining a good biological response. Copyright © 2008 John Wiley &amp; Sons, Ltd.