Materials In Simulated Body Fluid Research Articles

Calcium Citrate Amount and Gelatine Source Impact on Hydroxyapatite Formation in Bone Regeneration Material in Simulated Body Fluid.

Bone grafting is crucial for bone regeneration. Recent studies have proposed the use of calcium citrate (CC) as a potential graft material. Notably, citrate does not inhibit hydroxyapatite (HAp) formation at specific calcium-to-citrate molar ratios. Octacalcium phosphate (OCP)/gelatine (Gel) composites, which are commonly produced from porcine Gel, are valued for their biodegradability and bone replacement capability. This study introduces fish Gel as an alternative to porcine Gel because of its wide acceptance and eco-friendliness. This is the first study to examine the interaction effects between two osteogenic materials, OCP/CC, and the influence of different gelatine matrix components on HAp formation in an SBF. Samples with varying CC contents were immersed in an SBF for 7 d and analysed using various techniques, confirming that high CC doses prevent HAp formation, whereas lower doses facilitate it. Notably, small-sized OCP/CC/porcine Gel composites exhibit a high HAp generation rate. Porcine Gel composites form denser HAp clusters, whereas fish Gel composites form larger spherical HAps. This suggests that lower CC doses not only avoid inhibiting HAp formation but also enhance it with the OCP/Gel composite. Compared with porcine Gel, fish Gel composites show less nucleation but an increased crystal growth for HAp.

Enhanced corrosion resistance of CoCrMo by laser-based surface modification

Biomedical grade cobalt–chromium–molybdenum (CoCrMo) alloys are extensively used for load-bearing biomedical applications such as hip and knee implants due to their exceptional biocompatible and biomechanical properties. However, the strain-induced martensite ε-phase development during contact loading results in thin oxide layers that are prone to fracture leading to corrosion. The formation of thin oxide layers is undesirable for long-term deployment. We employed laser-texturing to enhance the corrosion resistance of the material in simulated body fluid by the formation of hcp ε-phase martensite and via the formation of oxide layers. However, partial formation of hcp ε-phase martensite was observed. By means of central composite design-based response surface methodology, three laser parameters such as average laser power, texture density and the number of passes were optimised for maximal open circuit potential, an indicator for minimal corrosion. The textured surfaces were found to assist in the cellular proliferation of fibroblasts and inhibit bacterial growth.

Preparation of hydroxyapatite/bioactive glass/collagen scaffolds for use in tissue engineering

Bioactive glass (BG) and hydroxyapatite (HAp) are widely used in tissue engineering, but their loss of shape and migration under load require their immobilization in a polymer matrix. This study involved the initial mixture of BG and HAp particles in ethanol. Heat treatment of the BG/HAp blends at temperatures between 600°C and 800°C induced subsequent structural changes, an aspect overlooked in the literature. By examining these changes, we have gained valuable insight into the properties and behavior of the prepared composite. The optimized composition (75 HAp/25 BG) and heat treatment temperature (800°C) were determined, followed by the incorporation of the ceramic powder into a collagen matrix and sterilization with ethylene oxide. Soaking the prepared materials in simulated body fluid resulted in the rapid formation of HAp, indicating favorable biocompatibility. The approach used here balances desired properties with economic considerations, resulting in affordable biomaterials for biomedical applications.

Imparting bioactivity to CP−Titanium with sputtered TiBN interlayer and electrophoretically grown bioglass overlay

Surface-modified implant materials with improved physicochemical properties and biocompatibility are vital for determining osseointegration and to enhance bone anchorage. Herein, titanium boron nitride (TiBN) thin films of thickness 3.4 μm were coated as an interlayer on sandblasted Ti plates by confocal D.C. magnetron sputtering using Ti and TiB2 targets. Nanoindentation tests showed a hardness of 27 GPa for the thin film. The bioactivity of the as-prepared coatings was enriched by introducing bioglass (BG), 45S5, overlay via electrophoretic deposition. The nanocrystalline microstructure with lattice parameter 4.2 Å, surface topology and vibration modes/surface chemistry of the coatings were comprehensively studied using microscopic and spectroscopic techniques. Swab inoculation assay, cellular viability assay and hemocompatibility studies revealed that bioglass overlaid thin films exhibited antibacterial property and cytocompatibility with no clot formation. Contact angle measurements showed that 45S5 bioglass-coated substrates were hydrophilic. Biocorrosion studies of the prepared implant materials in simulated body fluid (SBF) revealed the corrosion resistance of bioglass overlaid specimens with the corrosion potential (Ecorr) shifting towards a relatively positive value and the corrosion current density (Icorr) decreasing in the order bare Ti > TiBN >45S5/TiBN coated Ti substrates. Obtained experimental results suggests that the as-prepared 45S5 glass-coated TiBN/Ti plates could be a potential implantable candidate with synergistic cytocompatibility and corrosion resistance.

Hybrid Polylactic-Acid–Pectin Aerogels: Synthesis, Structural Properties, and Drug Release

Wound-dressing materials often include other materials stimulating wound healing. This research describes the first formulation of biodegradable hybrid aerogels composed of polylactic acid and pectin. The prepared hybrid material showed a highly porous structure with a surface area of 166 ± 22.6 m2·g-1. The addition of polylactic acid may have decreased the surface area of the pure pectin aerogel, but it improved the stability of the material in simulated body fluid (SBF). The pure pectin aerogel showed a high swelling and degradation ratio after 3 h. The addition of the polylactic acid prolonged its stability in the simulated body fluid from 24 h to more than one week, depending on the amount of polylactic acid. Biodegradable aerogels were loaded with indomethacin and diclofenac sodium as model drugs. The entrapment efficiencies were 63.4% and 62.6% for indomethacin and diclofenac sodium, respectively. Dissolution of both drugs was prolonged up to 2 days. Finally, sodium percarbonate and calcium peroxide were incorporated into the bioaerogels as chemical oxygen sources, to evaluate oxygen generation for potential wound healing applications.

Effect of simulated body fluid formulation on orthopedic device apatite-forming ability assessment.

Integration of native bone into orthopedic devices is a key factor in long-term implant success. The material-tissue interface is generally accepted to consist of a hydroxyapatite layer so bioactive materials that can spontaneously generate this hydroxyapatite layer after implantation may improve patient outcomes. Per the ISO 22317:2014 standard, "Implants for surgery - In vitro evaluation for apatite-forming ability of implant materials," bioactivity performance statements can be assessed by soaking the material in simulated body fluid (SBF) and evaluating the surface for the formation of a hydroxyapatite layer; however, variations in test methods may alter hydroxyapatite formation and result in false-positive assessments. The goal of this study was to identify the effect of SBF formulation on bioactivity assessment. Bioglass® (45S5 and S53P4) and non-bioactive Ti-6Al-4V were exposed to SBF formulations varying in calcium ion and phosphate concentrations as well as supporting ion concentrations. Scanning electron microscopy and X-ray powder diffraction evaluation of the resulting hydroxyapatite layers revealed that SBF enriched with double or quadruple the calcium and phosphate ion concentrations increased hydroxyapatite crystal size and quantity compared to the standard formulation and can induce hydroxyapatite crystallization on surfaces traditionally considered non-bioactive. Altering concentrations of other ions, for example, bicarbonate, changed hydroxyapatite induction time, quantity, and morphology. For studies evaluating the apatite-forming ability of a material to support bioactivity performance statements, test method parameters must be adequately described and controlled. It is unclear if apatite formation after exposure to any of the SBF formulations is representative of an in vivo biological response. The ISO 23317 standard test method should be further developed to provide additional guidance on apatite characterization and interpretation of the results.

Modification of mesoporous structure of silver-doped bioactive glass with antibacterial properties for bone tissue applications

Silver-containing mesoporous bioglasses powders with SiO2–CaO–P2O5–Ag2O composition have been successfully synthesized by sol-gel and evaporation-induced self-assembly (EISA) methods in presence of various amounts of surfactant (Pluronic-F127). The morphology and crystal structure of the powders were characterized by scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD). Also, the textural properties of samples have been evaluated by adsorption-desorption, Langmuir and BET methods. Accordingly, powders had a smooth surface morphology with cubic mesoporous structure and a desired surface area and pore volume. The in vitro bioactivity was assessed by SEM, XRD and Fourier transform infrared spectroscopy (FTIR) analyses. All samples enhance the formation of HA after soaking the material in simulated body fluid (SBF) solution. The antibacterial property of samples was evaluated to investigate the effect of silver content in chemical composition. The results showed an adequate antibacterial activity of the samples against Escherichia coli, Salmonella and Listeria monocytogenes.

Conductive Polyaniline Patterns on Electrospun Polycaprolactone/Hydroxyapatite Scaffolds for Bone Tissue Engineering.

Currently, the challenge for bone tissue engineering is to design a scaffold that would mimic the structure and biological functions of the extracellular matrix and would be able to direct the appropriate response of cells through electrochemical signals, thus stimulate faster bone formation. The purpose of the presented research was to perform and evaluate PCL/n-HAp scaffolds locally modified with a conductive polymer-polyaniline. The material was obtained using electrospinning, and a simple ink-jet printing method was applied to receive the conductive polyaniline patterns on the surface of the electrospun materials. The samples of scaffolds were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal analysis (DSC, TGA), and infrared spectroscopy (FTIR) before and after immersion of the material in Simulated Body Fluid. The effect of PANI patterns on changes in the SBF mineralization process and cell morphology was evaluated in order to prove that the presented material enables the growth and proliferation of bone cells.

Structure, drug absorption, bioactive and antibacterial properties of sol-gel SiO2/ZrO2 materials

Zirconia widely used in biomedical applications has three crystalline forms, but the transformation from tetragonal to monoclinic is a serious problem in the biomedical field. In this regards, silica was added to stabilize the tetragonal zirconia phase. In fact, in this study four SiO2/ZrO2 composites with different percentages of zirconia were synthesized with the sol-gel method. The aim of the present study was to check the suitability of these materials as a vector in the adsorption of an active drug. After the sintering process at different temperatures the materials have been chemically and biologically characterized. The interactions between the inorganic matrices and the identification of the different crystalline phases depending on the temperature of the thermal treatment were evaluated by Fourier transform infrared (FTIR) spectroscopy and XRD analysis. Furthermore, the absorption of ampicillin was carried out using UV–Vis. The bioactivity was studied after soaking the materials in simulated body fluid (SBF) for 21 days, by observing the characteristic peaks of hydroxyapatite by FTIR analysis. Finally, after drug absorption the materials were incubated against Escherichia coli in order to evaluate the antibacterial properties and the release of the drug from the different composites.

Effect of immersion time on corrosion behavior of Mg-2Nd-0.5Zn-0.4Zr-1Y alloy in simulated body fluid

The purpose of this paper is to investigate the corrosion behavior of biodegradable Mg-2Nd-0.5Zn-0.4Zr-1Y alloy immersed in simulated body fluid (SBF) with different immersion times. The corrosion behavior of the materials in SBF was determined by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), electrochemical test and immersion tests. The results indicated that the Mg-2Nd-0.5Zn-0.4Zr-1Y alloy was comprised of α-Mg matrix, Mg12Nd, Mg24Y5 and MgZn phases and the average grain size was about 60 μm. The corrosion started from the weak region between the eutectic phase/Zr-rich region and α-Mg matrix. The corrosion products were mainly composed of Mg(OH)2, CaCO3 and Ca5(PO4)3(OH). The corrosion form of Mg-2Nd-0.5Zn-0.4Zr-1Y alloy was mainly pitting corrosion. With the prolongation of immersion time, the pitting began to grow and eventually developed into filiform corrosion. The degradation behavior of the alloy in SBF included main four stages: (a) stage 1: galvanic corrosion; (b) stage 2: pitting corrosion; (c) stage 3: accumulated hydrogen bursting the corrosion layer and (d) stage 4: lateral and longitudinal growth of pitting.

Preparation and Histological Study of Multi-Walled Carbon Nanotubes Bone Graft in Management of Class II Furcation Defects in Dogs.

BACKGROUND:The main target of periodontal disease and alveolar bone defeat treatment is the regeneration of the lost structures.AIM:This work deals with the evaluation of the effect of functionalised multi-walled carbon nanotubes (MWCNTs), as grafting material in the management of furcation defects created in dogs.MATERIAL AND METHODS:Potential cytotoxicity of the grafting material was assessed. Scanning electron microscope (SEM) and energy dispersive x-ray (EDX) analysis after incubation of the grafting material in simulated body fluid (SBF) at pH 7.4 and 37°C for one week was done. In six healthy mongrel dogs’ full-thickness mucoperiosteal flaps were raised on the buccal aspects to create two walls intrabony defects at the furcation areas. The mandibular premolar area received the grafting material. Histological evaluation was carried out at 1, 2- and 3-months’ period.RESULTS:Cytotoxicity results proved the safety of grafting material application. The prepared material exhibited good Ca-apatite crystal patterns at the surface revealed by SEM and high calcium content showed by EDX results. Good bone formation ability was also apparent histologically.CONCLUSION:The prepared grafting material (MWCNTs) can serve as a delivery vehicle for osteogenic cells and osteogenic growth factor proteins in the bone development process.

Nanocrystalline Zn2+ and SO42- binary doped fluorohydroxyapatite: A novel biomaterial with enhanced osteoconductive and osteoinconductive properties.

In this study, we have successfully doped hydroxyapatite (HA) with zinc (Zn2+), sulphate (SO42-) and fluoride (F-) ions to develop a new composition of bioceramic, Ca10-x Znx(PO4)6-y(SO4)y(OH)2-z-yFz(SO4)y, (x = 0, 0.2, 0.6, 1.0, y = 0, 0.5 and z = 0,1.0 mol), using wet precipitation method. The obtained materials were analysed using XRD, FTIR, FESEM, and XPS techniques to investigate the phase purity, particle morphology and elemental composition, respectively. A model anticancer drug (Doxorubicin, DOX) was loaded onto the surface of the Zn/SO4-FHA materials. About 100% loading of DOX with a controlled release profile was obtained. Degradation of materials in Simulated body fluid (SBF) was greatly improved with the incorporation of Zn2+/SO42- ions in comparison to HA/FHA, which makes it highly bioactive materials. In vitro cell viability and adhesion of Human fetal osteoblast (hFOB) cell were investigated. Cell viability has demonstrated that the hFOB cells proliferated at a high rate on Zn/SO4-FHA materials, confirming the in vitro biocompatibility of the materials. Alkaline phosphatase (ALP) activity and intracellular calcium deposition of hFOB cells seeded on 1ZnSO4-FHA disc surface was statistically higher than observed on pure HA and FHA discs, indicating that hFOB cells differentiated into mature osteoblasts on 1Zn/SO4-FHA disc surfaces. Taken together, our results suggest that HA substituted by (Zn2+, 0.2 mol), (SO42-, 0.5 mol) and (F-, 1 mol) (1Zn/SO4-FHA) material was a promising material for hard tissue scaffolds.

Marginal Gaps between 2 Calcium Silicate and Glass Ionomer Cements and Apical Root Dentin

IntroductionThe outcome of periapical surgery has been directly improved with the introduction of novel material formulations. The aim of the study was to compare the retrograde obturation quality of the following materials: calcium silicate (Biodentine; Septodont, Saint-Maur-des-Fosses, France), mineral trioxide aggregate (MTA+; Cerkamed Company, Stalowa Wola, Poland), and glass ionomer cement (Fuji IX; GC Corporation, Tokyo, Japan). MethodsMaterials' wettability was calculated concerning the contact angles of the cements measured using a glycerol drop. Cements' porosity was determined using mercury intrusion porosimetry and micro–computed tomographic (μCT) imaging. Extracted upper human incisors were retrofilled, and μCT analysis was applied to calculate the volume of the gap between the retrograde filling material and root canal dentin. Experiments were performed before and after soaking the materials in simulated body fluid (SBF). ResultsNo statistically significant differences were found among the contact angles of the studied materials after being soaked in SBF. The material with the lowest nanoporosity (Fuji IX: 2.99% and 4.17% before and after SBF, respectively) showed the highest values of microporosity (4.2% and 3.1% before and after SBF, respectively). Biodentine had the lowest value of microporosity (1.2% and 0.8% before and after SBF, respectively) and the lowest value of microgap to the root canal wall ([10 ± 30] × 10−3 mm3). ConclusionsBiodentine and MTA possess certain advantages over Fuji IX for hermetic obturation of retrograde root canals. Biodentine shows a tendency toward the lowest marginal gap at the cement-to-dentin interface.

Biodegradation of hydroxyapatite coated Rex-734 alloy with silver and selenium/chitosan substitutions: In vitro analysis

Abstract Hydroxyapatite (HA) based bioceramic coatings; such as single-HA, double layered with Silver-Ag, Selenium-Se and Chitosan substitutions on Rex-734 alloy were executed by using the sol-gel method. Surface morphologies and adhesion strengths of the obtained coatings were investigated and coating material weight losses and metal ion releases from the substrates were determined in SBF (Simulated Body Fluid) environment. The coatings were characterized by SEM, EDS, XRD and adhesion strengths between the substrate and bioceramic coatings were measured with adhesion tests. SEM analyses revealed that crack-free surface morphologies were obtained in all bioceramic coatings. The coatings were kept in SBF for immersion periods from one to four weeks and the weight loss (%) in coatings and changes in ion release rates were determined. HA/Ag double layered coatings applied on the Rex-734 alloy increased the adhesion strength and accordingly reduced the weight losses (%) of coating materials in SBF. Se/Chitosan double layered coatings were found to decrease the adhesion strength and increase the weight losses (%) in SBF. Additionally, all bioceramic coatings were observed to prevent the elemental ion release by physical barrier effect for the release of metal ions during the four weeks immersion period in SBF.

In vitro behaviour of Nurse's Ass-phase: A new calcium silicophosphate ceramic

In the present study, a new single phase Si–Ca–P-based ceramic (called Nurse's Ass) was obtained and its in vitro behaviour was explored for potential bone tissue regeneration. A porous Si–Ca–P single phase ceramic was obtained from high-temperature sintering of previously synthesised γ-dicalcium silicate and β-tricalcium phosphate. Apatite-mineralisation ability and the dissolution rate were systematically studied by immersing the material in simulated body fluid (SBF) for several time points. Massive new dense calcium deficient hydroxyapatite (CDHA) layer formation was observed at the SBF-sample interface. Adjacent to the dense CDHA layer, a porous structure developed parallel to the interface, formed by the pseudomorphic transformation of Si–Ca–P (Nurse's Ass) into CDHA. The cell attachment test showed that the new material supported adult human bone marrow-derived mesenchymal stem cells (hMSCs) adhesion and spreading, and cells came into close contact with the ceramic surface during an extended 28-day culture. These findings indicate that the new calcium silicophosphate ceramic possesses good bioactivity and biocompatibility, and might be a promising bone graft substitute.

Electrodeposition of sustainable fluoridated hydroxyapatite coatings on 316L stainless steel for application in bone implant

Abstract Fluoridated hydroxyapatite (FHAp) coatings were deposited on 316L stainless steel (316LSS) substrate by the electrodeposition method. Different concentrations of F– ion were incorporated into the apatite structure by adding NaF into the electrolyte solution. The coating was uniform and dense, with thickness of 9.6 µm, and F– ions were doped on HAp with mass percentage of 1.7%; F– concentration was 0.002 M. Results of IR, energy-dispersive X-ray (EDX), X-ray and scanning electron microscopy (SEM) analysis showed that the obtained coatings were single phase crystals of HAp, of a cylinder shape with average size of about 100 nm×30 nm, and characterized for the molecular structure FHAp. The in vitro test of 316LSS, HAp/316LSS and FHAp/316LSS materials in simulated body fluid (SBF) solution was realized with different immersion times. After 21 immersion days in SBF solution, the apatite crystals have a cactus-like shape, and they grow to form a thick block on the surface of FHAp/316LSS leading to the decrease of the corrosion current density during the immersion process in the SBF solution.

Apatite-forming ability of vinylphosphonic acid-based copolymer in simulated body fluid: effects of phosphate group content.

Phosphate groups on materials surfaces are known to contribute to apatite formation upon exposure of the materials in simulated body fluid and improved affinity of the materials for osteoblast-like cells. Typically, polymers containing phosphate groups are organic matrices consisting of apatite-polymer composites prepared by biomimetic process using simulated body fluid. Ca(2+) incorporation into the polymer accelerates apatite formation in simulated body fluid owing because of increase in the supersaturation degree, with respect to apatite in simulated body fluid, owing to Ca(2+) release from the polymer. However, the effects of phosphate content on the Ca(2+) release and apatite-forming abilities of copolymers in simulated body fluid are rather elusive. In this study, a phosphate-containing copolymer prepared from vinylphosphonic acid, 2-hydroxyethyl methacrylate, and triethylene glycol dimethacrylate was examined. The release of Ca(2+) in Tris-NaCl buffer and simulated body fluid increased as the additive amount of vinylphosphonic acid increased. However, apatite formation was suppressed as the phosphate groups content increased despite the enhanced release of Ca(2+) from the polymer. This phenomenon was reflected by changes in the surface zeta potential. Thus, it was concluded that the apatite-forming ability of vinylphosphonic acid-2-hydroxyethyl methacrylate-triethylene glycol dimethacrylate copolymer treated with CaCl2 solution was governed by surface state rather than Ca(2+) release in simulated body fluid.

Novel bioactive materials developed by simulated body fluid evaluation: Surface-modified Ti metal and its alloys.

Until the discovery of the bone-bonding activity of Bioglass by Hench et al. in the early 1970s, it had not been demonstrated that a synthetic material could bond to living bone without eliciting a foreign body reaction. Since then, various kinds of materials based on calcium phosphate, such as sintered hydroxyapatite and β-tricalcium phosphate have also been shown to bond to living bone. Until the discovery of the bone-bonding activity of Ti metal formed with a sodium titanate surface layer by the present authors in 1996, it had not been shown that a metallic material could bond to living bone. Since then, various kinds of surface-modified Ti metal and its alloys have been found to bond to living bone. Until the discovery of the osteoinduction of porous hydroxyapatite by Yamasaki in 1990, it was unknown whether a synthetic material could induce bone formation even in muscle tissue. Since then, various kinds of porous calcium phosphate ceramics have been shown to induce osteoinduction. Until the discovery of osteoinduction induced by a porous Ti metal formed with a titanium oxide surface layer by Fujibayashi et al. in 2004, it had been unclear whether porous metals would be able to induce osteoinduction. These novel bioactive materials have been developed by systematic research into the apatite formation that occurs on surface-modified Ti metal and its related materials in an acellular simulated body fluid (SBF) having ion concentrations almost equal to those of human blood plasma. Some of the novel bioactive materials based on Ti metal are already in clinical use or clinical trials, such as artificial hip joints and spinal fusion devices. In the present paper, we review how these novel bioactive materials based on Ti metal have been developed based on an evaluation of apatite formation in SBF. Without the SBF evaluation, these novel bioactive materials would most likely never have been developed. On the basis of systematic study of apatite formation on a material in a simulated body fluid, various kinds of novel bioactive materials possessing not only bone-bonding activity and but also various other functions such as bone growth promotion, antibacterial activity and osteoinduction have been developed. Some of them are already successfully applied to clinical applications or trials for artificial hip joints and spinal fusion devices. It is shown in the present paper how these novel bioactive materials have been developed.

Er3+/Yb3+ co-doped bioactive glasses with up-conversion luminescence prepared by containerless processing

Er3+/Yb3+ co-doped bioactive glasses were prepared via containerless processing in an aerodynamic levitation furnace. The as-prepared glasses were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) equipped with energy dispersive X-Ray spectroscopy (EDX). The up-conversion luminescence of as-prepared glasses was measured using an Omni- 3007 spectrometer. Furthermore, the in vitro bioactivity was evaluated by soaking the materials in simulated body fluid, and the biocompatibility was evaluated in MC3T3-E1 cell culture.The results show that containerless processing is a unique method to prepare homogeneous rare earth doped bioactive glasses. The obtained Er3+/Yb3+ co-doped glasses show green and red up-conversion luminescence at the excitation of 980nm laser. The XRD analysis confirmed that calcium silicate powders, as starting materials, were completely transformed from the original multi-crystalline phase (CS-P) into the amorphous-glassy phase (CS-G, EYS, LCS) via containerless processing. The SEM observation combined with EDX and FTIR analyses showed that the as-prepared glasses were bioactive. The cell proliferation assay also revealed that the as-prepared glasses were biocompatible and nontoxic to MC3T3-E1 cells. This study suggests that the luminescent bioactive glasses prepared by containerless processing could be used for studying biodegradation of bone implantation materials.

Preparation of Mg–Zn bimetallic doped Na-containing bioceramic from sodium metasilicate

Glass–ceramic materials in the composition (mol%) 23.5 Na2O–23.5CaO–xMgO–xZnO–47SiO2–(6-2x) P2O5 (x = 0 and 1.5) were prepared by the sol–gel technique using sodium metasilicate (Na2SiO3) as source of Na2O and SiO2. Bioactivity was investigated in vitro by examining apatite formation on the surface of the samples after treatment in acellular simulated body fluid (SBF). Formation of bioactive apatite layer on the samples was confirmed by using scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscopy. Reactivity of the materials in SBF was based on changes in pH and ionic concentration of the solution as a function of immersion duration. Results obtained indicated that the sample doped with Mg and Zn exhibited greater crystallinity containing phases such as CaMgSi2O6, Ca2MgSi2O7, CaSiO3, Na2CaSi3O9, Na2CaSi3O8, CaZnSi2O7 and a new secondary phase, clinohedrite (CaZnSiO4·H2O), while the undoped sample contained a single crystalline phase composed of Na2Ca2Si3O9. After 7 days in SBF, phase transformation occurred at different rates on the materials leading to formation of apatite layer. The result shows that controlled amounts of MgO and ZnO may be useful in tuning up the mechanical properties of bioactive glasses while maintaining bioactivity.