Simulated Body Fluid Test Research Articles

Friction stir processing of AZ31 alloy to improve the mechanical, biodegradation, and in vitro biocompatible characteristics

The aim of the study was to improve the mechanical, biodegradation and in vitro biocompatible characteristics of as received rolled AZ31 (Mg-1%Zn-3%Al) alloy by develop the surface composite of Mg-Titania. The surface composite was developed by friction stir processing (FSP) and it’s used for prosthetic applications. The influence of tool rotation speed and number of FSP passes on grain structure, grain refinement, tensile strength, hardness, in vitro degradation rate and in vitro biocompatibility were explored. The obtained results support the capability of FSP in terms of mechanical strengthening, refinement of grain structure, dispersion of reinforcement (i.e. TiO2) and controlled degradation rate. Grain structure at stir zone, advancing side and retreating side were investigated. The large grains in the alloy were reduced to a fine equiaxial grains of average dimension of ≈ 3 μm by 3rd pass of FSP. The process was performed under two different tool rotation speed, i.e. 1550 and 2260 RPM. The addition of second phase in the matrix significantly improve the grain refinement. The results obtained from tensile test revealed the improvement in the percentage elongation without compromising the strength. The micro hardness of specimens of different parametric combination were evaluated and found ≈ 30–50% improvement in the micro hardness. The degradation rate by immersion test in simulated body fluid (SBF) for 3, 6 and 10 days were performed and found a significant reduction in degradation rate. The MTT assay for the biocompatibility performed by indirect method, the results validate the non-toxic behavior of processed specimen.

Effect of Atmospheric Pressure Plasma Jet Treatments on Magnesium Phosphate Cements: Performance, Characterization, and Applications.

Atmospheric pressure plasma treatments are nowadays gaining importance to improve the performance of biomaterials in the orthopedic field. Among those, magnesium phosphate-based cements (MPCs) have recently shown attractive features as bone repair materials. The effect of plasma treatments on such cements, which has not been investigated so far, could represent an innovative strategy to modify MPCs' physicochemical properties and to tune their interaction with cells. MPCs were prepared and treated for 5, 7.5, and 10 min with a cold atmospheric pressure plasma jet. The reactive nitrogen and oxygen species formed during the treatment were characterized. The surfaces of MPCs were studied in terms of the phase composition, morphology, and topography. After a preliminary test in simulated body fluid, the proliferation, adhesion, and osteogenic differentiation of human mesenchymal cells on MPCs were assessed. Plasma treatments induce modifications in the relative amounts of struvite, newberyite, and farringtonite on the surfaces on MPCs in a time-dependent fashion. Nonetheless, all investigated scaffolds show a good biocompatibility and cell adhesion, also supporting osteogenic differentiation of mesenchymal cells.

Influence of gelatin-TiO2-Al2O3 nanocomposite coatings on enhancement of wear and corrosion resistance of SKD11 steel

The performance and lifespan of steel mechanical components that experience wear and corrosion hinges on their surface properties, such as wear resistance, hardness, and corrosion resistance. Therefore, a surface coating method is vital to enhance the surface properties of this material. In this study, the influence of gelatin-TiO2-Al2O3 (GTA) nanocomposite coatings on the wear and corrosion resistance of the SKD11 steel (SS) surface was investigated with the purpose of enhancing the lifespan of this material. The nanocomposite coatings were prepared using a sol-gel spin-coating method. Microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements were used to analyze the surface morphology, molecular interactions, microstructure, and wettability of the coatings. The corrosion resistance is also determined by electrochemical tests in simulated body fluid (SBF), although the wear properties are evaluated using a ball-on-disc tribotester. Subsequently, a comparative analysis of pure gelatin (G) G-coated and uncoated samples is performed. These results confirm the formation of homogeneous, crack-free, and defect-free coatings on the substrates. Compared to the G-coated and uncoated samples, the anti-wear and anti-corrosion performances of the substrates were noticeably enhanced by the incorporation of gelatin and TiO2–Al2O3 coatings, structural advantages, and hydrophilicity. Furthermore, compared with the uncoated sample, the prepared GTA sample improved the friction coefficient and wear rate of the substrates by 45.16 % and 39.19 %, respectively.

Bioactive Glasses Enriched with Strontium or Zinc with Different Degrees of Structural Order as Components of Chitosan-Based Composite Scaffolds for Bone Tissue Engineering.

The development of innovative biomaterials with improved integration with bone tissue and stimulating regeneration processes is necessary. Here, we evaluate the usefulness of bioactive glasses from the SiO2-P2O5-CaO system enriched with 2 wt.% SrO or ZnO in the manufacturing of chitosan-based scaffolds. Bioglasses produced using the sol-gel method were subjected to thermal treatment in different regimes. Chitosan/bioglass composites were produced with a weight ratio. Bioglasses were evaluated via TG-DTA, FTIR, and SEM-EDS before and after incubation in simulated body fluid (SBF). The release of ions was tested. The cytocompatibility of the composites in contact with MG63 osteoblast-like cells was evaluated. The results showed that the presence of the crystalline phase decreased from 41.2-44.8% for nonmodified bioglasses to 24.2-24.3% for those modified with ZnO and 22.0-24.2% for those modified with SrO. The samples released Ca2+, Zn2+, and/or Sr2+ ions and were bioactive according to the SBF test. The highest cytocompatibility was observed for the composites containing nonmodified bioglasses, followed by those enriched with SrO bioglasses. The least cytocompatible were the composites containing ZnO bioglasses that released the highest amount of Zn2+ ions (0.58 ± 0.07 mL/g); however, those that released 0.38 ± 0.04 mL/g were characterised by acceptable cytocompatibility. The study confirmed that it is feasible to control the biological performance of chitosan/bioglass composites by adjusting the composition and heat treatment parameters of bioglasses.

Structurally modified bioglasses synthesized using agro-food wastes and conventional sources for bone regeneration application

Bioglasses are synthesized using the melt-quench technique using two different sources (biowastes and conventional chemicals). These glasses are characterized and tested using various experimental techniques such as X-ray diffraction, field emission-scanning electron microscopy, energy dispersive spectroscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, and in-vitro testing in simulated body fluid (SBF). The physical parameters, such as the density of glass samples, are 2.7 ± 0.01 g/cm3 and tend to decrease with increased MgO in glass composition. The MgO increases the phase separation tendency in glasses and stabilizes the hydroxyapatite layer (HAp) with an optimized Ca/P ratio of 1.67. MgO retards the degradation of bioglasses in SBF due to its two different roles in silicate and phosphate structural units. The controlled dissolution rates present an exciting prospect for chemical interactions and accelerated osteointegration in bone regeneration, bone grafting, and many dental applications.

Enhanced in-vitro biodegradation, bioactivity, and mechanical properties of Mg-based biocomposite via addition of calcium-silicate-based bioceramic through friction stir processing as resorbable temporary bone implant

Bioabsorbable Mg and alloys have been used as metallic biomaterials for orthopedic implant applications due to their similar mechanical properties to human natural bone. High biodegradation rate is the main reason for limiting clinical applications of Mg and alloys in biological media. In order to achieve long-lasting bio applications of bioabsorbable WE43 Mg alloy, it is necessary to improve strength and bioactivity and control biodegradation rate of this material. In this study, Mg-based biocomposites are produced using friction stir processing (FSP) by addition of wollastonite (CaSiO3) calcium-silicate-based bioactive reinforcing particle into Mg matrix. The results showed that applied severe plastic deformation during FSP caused formation of ultra-fine grain structure with homogenous distribution of secondary phase particles, which resulted in a remarkable improvement of ductility, strength and load bearing capacity of FSPed Mg matrix. Also, biodegradation behavior of resulting biocomposite was evaluated using electrochemical methods and in-vitro immersion test in simulated body fluid (SBF) and phosphate-buffered saline (PBS) at 37.5 °C. The results revealed that processed bioabsorbable Mg alloy showed a lower biodegradation rate compared to monolithic Mg alloy. Furthermore, the presence of wollastonite bioceramic particles significantly enhanced strength and reduced biodegradation of the Mg-based biocomposite. Moreover, the addition of wollastonite bioceramic particles positively affected the bioactivity of Mg matrix by forming a cauliflower shaped bone-like hydroxyapatite layer on the surface after 28 days of immersion in SBF and stimulate bone tissue regeneration.

Fabrication and Characterisation of Calcium Sulphate Hemihydrate Enhanced with Zn- or B-Doped Hydroxyapatite Nanoparticles for Hard Tissue Restoration.

A composite based on calcium sulphate hemihydrate enhanced with Zn- or B-doped hydroxyapatite nanoparticles was fabricated and evaluated for bone graft applications. The investigations of their structural and morphological properties were performed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy techniques. To study the bioactive properties of the obtained composites, soaking tests in simulated body fluid (SBF) were performed. The results showed that the addition of 2% Zn results in an increase of 2.27% in crystallinity, while the addition of boron causes an increase of 5.61% compared to the undoped HAp sample. The crystallite size was found to be 10.69 ± 1.59 nm for HAp@B, and in the case of HAp@Zn, the size reaches 16.63 ± 1.83 nm, compared to HAp, whose crystallite size value was 19.44 ± 3.13 nm. The mechanical resistance of the samples doped with zinc was the highest and decreased by about 6% after immersion in SBF. Mixing HAp nanoparticles with gypsum improved cell viability compared to HAp for all concentrations (except for 200 µg/mL). Cell density decreased with increasing nanoparticle concentration, compared to gypsum, where the cell density was not significantly affected. The degree of cellular differentiation of osteoblast-type cells was more accentuated in the case of samples treated with G+HAp@B nanoparticles compared to HAp@B. Cell viability in these samples decreased inversely proportionally to the concentration of administered nanoparticles. From the point of view of cell density, this confirmed the quantitative data.

Effect of MgF2 coating on stress corrosion cracking behavior of Mg−Zn−Ca alloy in simulated body fluid

The stress corrosion cracking behavior of Mg−3wt.%Zn−0.2wt.%Ca (MZC) alloy and fluoride (MgF2) coated Mg−3wt.%Zn−0.2wt.%Ca alloy (MZC-MF) for bone implant applications was investigated using slow strain- rate tensile (SSRT) tests in simulated body fluid (SBF). The results show that MgF2 coating could significantly improve the corrosion resistance and prolonged fracture failure time of MZC alloy. MgF2 coating also greatly reduced the stress corrosion cracking sensitivity of MZC alloy in SBF. Compared to MZC alloy, stress corrosion cracking sensitivity index (Iscc) of MZC-MF alloy decreased by 21% (ultimate tensile strength, UTS), 22% (time to failure, tf), 23% (elongation after fracture, δ), 7% (reduction ratio of cross-sectional area after fracture, ϕ) and 15% (inner product work, A), respectively.

Zinc-Doped Bioactive Glass/Polycaprolactone Hybrid Scaffolds Manufactured by Direct and Indirect 3D Printing Methods for Bone Regeneration.

A novel organic-inorganic hybrid, based on SiO2-CaO-ZnO bioactive glass (BG) and polycaprolactone (PCL), associating the highly bioactive and versatile bioactive glass with clinically established PCL was examined. The BG-PCL hybrid is obtained by acid-catalyzed silica sol-gel process inside PCL solution either by direct or indirect printing. Apatite-formation tests in simulated body fluid (SBF) confirm the ion release along with the hybrid's bone-like apatite forming. Kinetics differ significantly between directly and indirectly printed scaffolds, the former requiring longer periods to degrade, while the latter demonstrates faster calcium phosphate (CaP) formation. Remarkably, Zn diffusion and accumulation are observed at the surface within the newly formed active CaP layer. Zn release is found to be dependent on printing method and immersion medium. Investigation of BG at the atomic scale reveals the ambivalent role of Zn, capable of acting both as a network modifier and as a network former linking the BG silicate network. In addition, hMSCs viability assay proves no cytotoxicity of the Zn hybrid. LIVE/DEAD staining demonstrated excellent cell viability and proliferation for over seven weeks. Overall, this hybrid material either non-doped or doped with a metal trace element is a promising candidate to be translated to clinical applications for bone regeneration.

Synthesis and Characterization of Nano-Hydroxyapatite Obtained from Eggshell via the Hydrothermal Process and the Precipitation Method

Hydroxyapatite (HA) is a major component of the inorganic minerals in the hard tissues of humans and has been widely used as a biomedical ceramic material in orthopedic and dentistry applications. Because human bone contains several impurities, including carbonates, chlorides, fluorides, magnesium, and strontium, human bone minerals differ from stoichiometric HA. Additionally, natural bone is composed of nano-sized HA, and the nanoscale particles exhibit a high level of biological activity. In this paper, HA is prepared via the hydrothermal process because its reaction conditions are easy to control and it has been shown to be quite feasible for large-scale production. Therefore, the hydrothermal process is an effective and convenient method for the preparation of HA. Furthermore, eggshell is adopted as a source of calcium, and mulberry leaf extract is selectively added to synthesize HA. The eggshell accounts for 11% of the total weight of a whole egg, and it consists of calcium carbonate, calcium phosphate, magnesium carbonate, and organic matter. Eggshell contains a variety of trace elements, such as magnesium and strontium, making the composition of the synthesized HA similar to that of the human skeleton. These trace elements exert considerable benefits for bone growth. Moreover, the use of eggshell as a raw material can permit the recycling of biowaste and a reduction in process costs. The purpose of this study is to prepare HA powder via the hydrothermal method and to explore the effects of hydrothermal conditions on the structure and properties of the synthesized HA. The room-temperature precipitation method is used for the control group. Furthermore, the results of an immersion test in simulated body fluid confirm that the as-prepared HA exhibits good apatite-forming bioactivity, which is an essential requirement for artificial materials to bond to living bones in the living body and promote bone regeneration. In particular, it is confirmed that the HA synthesized with the addition of the mulberry leaf extract exhibits good in vitro biocompatibility. The morphology, crystallite size, and composition of the carbonated nano-HA obtained herein are similar to those of natural bones. The carbonated nano-HA appears to be an excellent material for bioresorbable bone substitutes or drug delivery. Therefore, the nano-HA powder prepared in this study has great potential in biomedical applications.

Enhancement of Antibacterial Properties, Surface Morphology and In Vitro Bioactivity of Hydroxyapatite-Zinc Oxide Nanocomposite Coating by Electrophoretic Deposition Technique

To develop medical-grade stainless-steel 316L implants that are biocompatible, non-toxic and antibacterial, such implants need to be coated with biomaterials to meet the current demanding properties of biomedical materials. Hydroxyapatite (HA) is commonly used as a bone implant coating due to its excellent biocompatible properties. Zinc oxide (ZnO) nanoparticles are added to HA to increase its antibacterial and cohesion properties. The specimens were made of a stainless-steel grade 316 substrate coated with HA-ZnO using the electrophoretic deposition technique (EPD), and were subsequently characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), stylus profilometry, electrochemical corrosion testing and Fourier transform infrared (FTIR) spectroscopy. Additionally, cross-hatch tests, cell viability assays, antibacterial assessment and in vitro activity tests in simulated body fluid (SBF) were performed. The results showed that the HA-ZnO coating was uniform and resistant to corrosion in an acceptable range. FTIR confirmed the presence of HA-ZnO compositions, and the in vitro response and adhesion were in accordance with standard requirements for biomedical materials. Cell viability confirmed the viability of cells in an acceptable range (>70%). In addition, the antibacterial activity of ZnO was confirmed on Staphylococcus aureus. Thus, the HA-ZnO samples are recommended for biomedical applications.

A strontium/vancomycin composite coating on titanium implants for preventing bacterial infection and improving osseointegration

Postoperative bacterial infection and poor osseointegration with surrounding bone tissue are not only the critical causes of implant failure but also the major challenges in clinical application. Hereby, Titania (TiO2) microporous/nanofiber coating was firstly prepared on the surface of titanium (Ti) material by alkali-heat treatment process, and strontium (Sr)-doped coating (TS) was then prepared by hydrothermal synthesis. Finally, polydopamine-assisted co-deposition technology was utilized to deposit vancomycin (Van) onto TS surface (TSV), thus obtaining a medical composite coating with antibacterial property and improved osseointegration ability. According to antibacterial test, TSV has not only a 99.99% killing effect on methicillin-resistant Staphylococcus aureus (MRSA), but also a good anti-biofilm ability. The cell experiments showed that TSV could enhance the adhesion and proliferation of osteoblasts. Compared with pure Ti and TS, TSV induces the formation of bone apatite in simulated body fluid (SBF) test quickly, indicating that the coating has good biological activity. According to histopathological observation and bone morphology analysis, TSV showed highly effective infection prevention and excellent osteointegration in vivo. These test results suggested that it is feasible to prevent implant-associated infection and promote osseointegration by functionalization of the implant, so as to provide a fresh direction for clinical research.

Effect of hydrothermal treatment on the surface characteristics and bioactivity of HAP based MAO coating on Ti-6Al-4V alloy

In this paper, the effects of hydrothermal treatment temperature and time on the surface characteristics and bioactivity of MAO coating on Ti-6Al-4V alloy were systematically investigated. The results showed that the amount of HAP formation on MAO coating gradually increased with the increase of hydrothermal treatment temperature and time. However, excessive temperature and time will cause the HAP pulverization on the MAO coating and cover its pores, which will be detrimental to osseointegration. It was found that when the hydrothermal treatment temperature and time were 200 °C and 24 h, respectively, the formed HAP could not be pulverized off, but could completely cover the MAO coating and retain its porous structure. Further bioactivity testing in simulated body fluid (SBF) revealed that the hydrothermally treated MAO coating generated more HAP crystal structures and covered a wider area than the sample without hydrothermal treatment. In addition, HAP first forms granules to fill the coating surface during the growth process. Then, with time HAP gradually embeds inside the coating and starts a new round of generation and fusion.

Scratch and Wear Behaviour of Co-Cr-Mo Alloy in Ringer’s Lactate Solution

Cobalt-chromium-molybdenum (Co-Cr-Mo) alloy is a material recommended for biomedical implants; however, to be suitable for this application, it should have good tribological properties, which are related to grain size. This paper investigates the tribological behaviour of a Co-Cr-Mo alloy produced using investment casting, together with electromagnetic stirring, to reduce its grain size. The samples were subjected to wear and scratch tests in simulated body fluid (Ringer's lactate solution). Since a reduction in grain size can influence the behaviour of the material, in terms of resistance and tribological response, four samples with different grain sizes were produced for use in our investigation of the behaviour of the alloy, in which we considered the friction coefficient, wear, and scratch resistance. The experiments were performed using a tribometer, with mean values for the friction coefficient, normal load, and tangential force acquired and recorded by the software. Spheres of Ti-6Al-4V and 316L steel were used as counterface materials. In addition, to elucidate the influence of grain size on the mechanical properties of the alloy, observations were conducted via scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD). The results showed changes in the structure, with a reduction in grain size from 5.51 to 0.79 mm. Using both spheres, the best results for the friction coefficient and wear volume corresponded to the sample with the smallest grain size of 0.79 mm. The friction coefficients obtained were 0.37 and 0.45, using the Ti-6Al-4V and 316L spheres, respectively. These results confirm that the best surface finish for Co-Cr-Mo alloy used as a biomedical implant is one with a smaller grain size, since this results in a lower friction coefficient and low wear.

Novel Bioactive Magnesium-Hopeite composite by friction stir processing for orthopedic implant applications

Magnesium (Mg) shows excellent potential for orthopedic implant applications owing to its equivalent mechanical properties compared to cortical bone and its biocompatibility. However, the rapid degradation rate of magnesium and its alloys in the physiological environment results in losing their mechanical integrity before complete bone healing. In light of this, friction stir processing (FSP), a solid-state process, is used to fabricate Hopeite (Zn(PO4)2.4H2O) reinforced novel magnesium composite. As a result of the novel composite fabricated by FSP, grain refinement of the matrix phase occurs significantly. The samples were immersed in simulated body fluid (SBF) for in-vitro bioactivity and biodegradability tests. The corrosion behavior of pure Mg, FSP Mg, and FSP Mg-Hopeite composite samples was compared using electrochemical and immersion tests in SBF. It found that Mg-Hopeite composite has better corrosion resistance than FSP Mg and pure Mg. Because of grain refinement and the presence of secondary phase Hopeite in the composite, the mechanical properties and corrosion resistance improved. The bioactivity test was performed in the SBF environment, and a rapid apatite layer was formed on the surface of Mg-Hopeite composite samples during the test. Osteoblast-like MG63 cells were exposed to samples, and the MTT assay confirmed the non-toxicity of the FSP Mg-Hopeite composite. The wettability of the Mg-Hopeite composite was improved than pure Mg. The present research findings showed that the novel Mg-Hopeite composite fabricated by FSP is a promising candidate for orthopedic implant applications, unreported in the literature.

Cold hydrostatic sintering of 45S5 bioactive glass

Fully amorphous 45S5 bioactive glass pellets were successfully consolidated at room temperature using cold hydrostatic sintering (CHS) and their acellular bioactivity was determined by immersion test in simulated body fluid (SBF). Crystalline 45S5 BG samples prepared using conventional sintering (TS) at 1050 °C were also tested. Preliminary results indicated the formation of hydroxyapatite (HAP) on the surfaces of both samples after immersion in SBF, which was confirmed using SEM, FTIR, and XRD analyses. The amount of hydroxyapatite increases by increasing the SBF immersion time. Results revealed that the amount of HAP crystalline phase was similar in both samples after 14 days of incubation in SBF (i.e., 23% in TS and 25% in CHS samples). The pellets prepared by TS resulted in a relative density of 95.6% and a hardness of about 3.5 GPa. On the other hand, CHS samples had a hardness of 1.2 GPa and a relative density of 75.1%, indicating the presence of a porous structure that can be beneficial for the interaction of the material with proteins and cells (both in vitro and in vivo).

In vitro degradation and corrosion evaluations of plasma electrolytic oxidized Mg–Zn–Ca–Si alloys for biomedical applications

Biodegradable calcium phosphate (CaP) ceramic coatings were prepared on self-designed Mg-2.0Zn-0.6Ca-xSi alloys by plasma electrolytic oxidation (PEO). The effect of calcium (Ca) and silicon (Si) on alloy microstructure and coating formation and biomineralization mechanisms were discussed. The in vitro bioactivity and degradability of CaP coatings were evaluated by immersion tests in simulated body fluid (SBF) solutions and trishydroxymethyl-aminomethane hydrochloric acid (Tris-HCl) buffer, respectively. The microstructure and chemical composition of the coatings, depositions and corrosion products were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and fourier transform infrared spectrometer (FT-IR). The electrochemical corrosion behavior of alloys and coatings was investigated using the electrochemical workstation. Results showed that the shape, quantity, size and distribution of second phases can be changed by the simultaneously addition of Ca and Si in Mg–Zn–Ca–Si alloys. The Si content in Mg-2.0Zn-0.6Ca-xSi alloy should not be higher than 0.8 wt%. The microstructure of Mg-2.0Zn-0.6Ca-xSi alloys can influence the formation and growth of PEO coating by altering the spark discharge characteristics. The plasma electrolytic oxidized Mg-2.0Zn-0.6Ca-0.8Si has potential to be served as biodegradable bone implant and cardiovascular stent.

In Vitro Investigation of Corrosion Control of Magnesium with Degradable Polycaprolactone Coatings for Cardiovascular Grafts

Magnesium is a promising metal for resorbable cardiovascular implants due to its high biocompatibility, high corrosion tendency, and mechanical properties. However, adapting its corrosion rate to the physiological healing processes is required to ascertain a safe graft function. A protective polymeric layer is supposed to slow down the corrosion rate of magnesium. Additionally, coatings can improve the host’s tissue interaction with the implant by implementing the local delivery of antibiotic drugs and growth or cell adhesion factors. However, little is known about the interaction of polymer-based coatings, their degradation, and magnesium corrosion. This study examines the corrosion mechanism of magnesium protected by spin coatings and electrospun fiber coatings under physiological conditions. Pure magnesium specimens were coated with polycaprolactone (PCL). The corrosion of the coated magnesium was evaluated using an immersion test in simulated body fluid. Spin coatings provided efficient protection against corrosive attacks and a significantly lower corrosion rate by 75% compared to uncoated magnesium. In contrast, fiber coatings did not provide relevant corrosion protection. On the other hand, magnesium corrosion caused the accelerated degradation of the PCL layer. A reliable and safe implant function is vital, especially in cardiovascular applications. Magnesium coating, therefore, should be carried out with spin coatings.

Bioactive Glass-Ceramic Scaffolds Coated with Hyaluronic Acid-Fatty Acid Conjugates: A Feasibility Study.

Promoting bone healing is a key challenge in our society that can be tackled by developing new implantable biomaterials provided with regenerative properties. In this work, the coating of three-dimensional porous glass-derived scaffolds with hyaluronic acid (HA)-fatty acids was investigated for the first time. The starting scaffolds, based on bioactive silicate glass, were produced by foam replication followed by sintering; then, HA-palmitate and HA-oleate conjugate coatings were deposited on the scaffold struts through a dipping procedure. FT-IR analysis confirmed the successful deposition of the coatings on the surface and struts of the scaffolds, the foam-like architecture of which was maintained as assessed by SEM investigations. The in vitro bioactivity of the HA-fatty-acid-coated scaffolds was studied by immersion tests in simulated body fluid and the subsequent evaluation of hydroxyapatite formation. The deposition of the polymeric coating did not inhibit the apatite-forming ability of scaffolds, as revealed by the formation of nanostructured hydroxyapatite agglomerates 48 h from immersion. These promising results motivate further investigation of these novel bioactive systems, which are expected to combine the bone-bonding properties of the glass with the wound-healing promotion carried out by the polymeric conjugates.

In vitro bioactivity and biocompatibility of magnesium implants coated with poly(methyl methacrylate) - bioactive glass composite

Magnesium (Mg) and its alloys have proved promising as biodegradable candidates for the repair of bone tissue. Despite the encouraging bio-related properties of Mg, its high corrosion rate in contact with body fluids still presents a major challenge. An efficient approach to address this issue is to provide a protective coating on Mg. The present research evaluates, for the first time, in vitro bioactivity and biocompatibility of a novel multifunctional composite coating based on poly(methyl methacrylate) (PMMA) biopolymer and bioactive glass (BG) particles on Mg-based implant. Electrophoretic deposition (EPD) was utilized to obtain this coating from a bi-component suspension. Coatings’ morphological analyses by scanning electron microscopy established that EPD provides a facile route for simultaneous deposition of the biopolymeric matrix and BG in the form of a dense and homogeneous coating on the surface of Mg. Chemical characterizations of the coatings performed by energy-dispersive spectroscopy and FT-IR spectroscopy confirmed the presence of both PMMA and BG components in the composite film. In vitro acellular bioactivity test in simulated body fluid (SBF) verified bone-like apatite formation on coatings due to the presence of BG particles. Additionally, in vitro cellular cytotoxicity using MTT assay demonstrated cellular viability in contact with the composite coatings. Moreover, the corrosion behavior of the pure Mg vs coated Mg samples in SBF was assessed electrochemically using linear polarization and impedance spectroscopy techniques. A significant increase in the polarization resistance from 65.89 Ω.cm 2 for uncoated Mg to 1365.1 Ω.cm 2 for Mg coated with a composite film (obtained from 45 g/L PMMA and 3.5 g/L BG suspension) was observed. This indicated a reduction of 95.17% in the corrosion rate of Mg substrate by application of a composite coating. The dramatic reduction in Mg substrate corrosion rate accompanied by in vitro bioactivity and cytocompatibility of the developed composite, reflect the high potential of the present strategy in the modification of Mg-based implants for successful bone tissue engineering applications. • Novel bioactive and corrosion-resistant composite coating on Mg biomedical implant • PMMA facilitates bioactive glass deposition via a facile electrophoretic method • Composite coatings were bioactive due to apatite formation in simulated body fluid • 95.17% reduction in corrosion rate in composite-coated Mg vs bare Mg • Coatings supported the growth of MG63 cells and were non-cytotoxic