Applications In Bone Implants Research Articles

Producing High Wettable Surface on Pure Titanium Sheets by Shot Peening for Bone Implant Applications

Pure titanium (Ti) sheets were subjected to shot peening to achieve grain refinement at the surface. Microstructural studies revealed significant grain refinement at the surface of the Ti sheet after shot peening. The affected thickness of the grain refined region was measured as 150 µm at the cross-section. Due to the fine grain structure, higher hardness was measured for the processed surface. X-ray diffraction studies of the processed sample showed peak broadening for processed Ti due to shot peening. Wettability studies conducted by contact angle measurements clearly showed increased hydrophilicity for the processed Ti as reflected in the lower contact angles. Increased surface energy was calculated for the shot-peened Ti, which can be attributed to the role of the increased fraction of grain boundaries due to microstructure modification. The results demonstrate the potential of the shot peening process to improve the surface wettability and further directly enhance the bioactivity of the Ti implant.

Carbonated Hydroxyapatite-Based Honeycomb Scaffold Coatings on a Titanium Alloy for Bone Implant Application—Physicochemical and Mechanical Properties Analysis

In this work, carbonated hydroxyapatite (CHA) based on abalone mussel shells (Haliotis asinina) is synthesized using the co-precipitation method. The synthesized CHA was mixed with honeycomb (HCB) 40 wt.% for the scaffold fabrication process. CHA and scaffold CHA/HCB 40 wt.% were used for coating a Titanium (Ti) alloy using the electrophoretic deposition dip coating (EP2D) method with immersion times of 10, 20, and 30 min. The synthesized B-type CHA with a stirring time of 45 min could have lower transmittance values and smaller crystallite size. Energy dispersive X-ray spectroscopy (EDS) showed that the Ca/P molar ratio was 1.79. The scaffold CHA/HCB 40 wt.% had macropore size, micropore size, and porosity of 102.02 ± 9.88 μm, 1.08 ± 0.086 μm, and 66.36%, respectively, and therefore it can also be applied in the coating process for bone implant applications due to the potential scaffold for bone growth. Thus, it has the potential for coating on Ti alloy applications. In this study, the compressive strength for all immersion time variations was about 54–83 MPa. The average compression strengths of human cancellous bone were about 0.2–80 MPa. The thickness obtained was in accordance with the thickness parameters required for a coating of 50–200 μm.

Nitrogen plasma immersion ion implantation treatment of Ti6Al7Nb alloy for bone-implant applications: Enhanced in vitro biological responses and in vivo initial bone-implant contact

Ti6Al4V alloy has been widely applied to orthopedic and dental implants; however, V ions release may have detrimental side effects. Ti6Al7Nb alloy provides mechanical characteristics similar to those of Ti6Al4V while with fewer potentially biological side effects. In the present investigation, nitrogen plasma immersion ion implantation (N-PIII) treatment was applied to Ti6Al7Nb alloy surfaces. N-PIII surface treatment formed a thin (< 100 nm) TiN-containing film on Ti6Al7Nb surface. A higher applied N-PIII voltage resulted in a higher TiN content on Ti6Al7Nb surface. Compared to the untreated Ti6Al7Nb surface, the N-PIII treated Ti6Al7Nb surface had higher surface roughness, hydrophilicity, hardness, corrosion resistance in simulated body fluid, protein (fibronectin) adsorption, and growth of human bone marrow mesenchymal stem cells, particularly Ti6Al7Nb surface with a higher TiN content. Initial bone-implant contact was investigated in vivo by implanting Ti6Al7Nb screw-type implants (with and without N-PIII treatment) in the femur of mini-pigs for two weeks. At two weeks of post-implantation, the N-PIII treated implant surface with a higher TiN content showed a higher initial bone-implant contact than other implants. Overall, the proposed N-PIII treatment of Ti6Al7Nb alloy surface (particularly with a higher TiN content) enhanced in vitro corrosion resistance, protein adsorption, and cell response as well as in vivo initial bone-implant contact.

Preparation of Al2O3-ZrO2 scaffolds with controllable multi-level pores via digital light processing

Multi-level porous material based on additive manufacturing, is a potentially disruptive material across multiple industries, including medical implants, thermal insulation and filtration. In this study, we propose a novel approach to fabricate materials with controllable pores via digital light processing (DLP) and decomposition of Al(OH)3. DLP can be used to fabricate macro pores bigger than 300 μm. And the decomposition of Al(OH)3 can result in micro pores of about 1 μm inside the scaffolds. The process parameters of curing, debinding and sintering temperature (1100−1500 ℃) of ceramic scaffolds with containing proportion of Al(OH)3 (0−60 wt.%) were examined. The results indicated multi-level porous ceramic scaffold has controllable porosity and pore size distribution and meets the requirement of implant strength. Biological test show that ceramic scaffolds with multi-level pores promoted osteoblast proliferation and adhesion. The multi-level porous ceramic scaffolds prepared by DLP and decomposition of Al(OH)3 have great prospects for the application in bone implants.

Copper-enriched diamond-like carbon coatings promote regeneration at the bone–implant interface

There have been several attempts to design innovative biomaterials as surface coatings to enhance the biological performance of biomedical implants. The objective of this study was to design multifunctional Cu/a-C:H thin coating depositing on the Ti-6Al-4V alloy (TC4) via magnetron sputtering in the presence of Ar and CH4 for applications in bone implants. Moreover, the impact of Cu amount and sp2/sp3 ratio on the interior stress, corrosion behavior, mechanical properties, and tribological performance and biocompatibility of the resulting biomaterial was discussed. X-ray photoelectron spectroscopy (XPS) revealed that the sp2/sp3 portion of the coating was enhanced for samples having higher Cu contents. The intensity of the interior stress of the Cu/a-C:H thin bio-films decreased by increase of Cu content as well as the sp2/sp3 ratio. By contrast, the values of Young's modulus, the H3/E2 ratio, and hardness exhibited no significant difference with enhancing Cu content and sp2/sp3 ratio. However, there was an optimum Cu content (36.8 wt.%) and sp2/sp3 ratio (4.7) that it is feasible to get Cu/a-C:H coating with higher hardness and tribological properties. Electrochemical impedance spectroscopy test results depicted significant improvement of Ti-6Al-4V alloy corrosion resistance by deposition of Cu/a-C:H thin coating at an optimum Ar/CH4 ratio. Furthermore, Cu/a-C:H thin coating with higher Cu contents showed better antibacterial properties and higher angiogenesis and osteogenesis activities. The coated samples inhibited the growth of bacteria as compared to the uncoated sample (p < 0.05). In addition, such coating composition can stimulate angiogenesis, osteogenesis and control host response, thereby increasing the success rate of implants. Moreover, Cu/a-C:H thin films encouraged development of blood vessels on the surface of titanium alloy when the density of grown blood vessels was increased with enhancing the Cu amount of the films. It is speculated that such coating can be a promising candidate for enhancing the osseointegration features.

The microstructure, bio-tribological properties, and biocompatibility of titanium surfaces with graded zirconium incorporation in amorphous carbon bioceramic composite films

One type of carbon-based bioceramic composite film, zirconium (Zr) incorporated amorphous carbon (Zr/a-C) gradient multilayer films (GMFs), is deposited on titanium (Ti) alloys by magnetron sputtering to attain superior biocompatibility and mechanical and bio-tribological properties. The morphologies and structure of Zr/a-C GMFs were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XRD and SEM and TEM analysis confirmed the gradient multilayer nature of the film, and the presence of nanostructured fcc-ZrC at the Zr/C layer interface for Zr content of 6.3 at.%. XPS analyses confirmed elevated sp2 bond content as a result of incorporating the Zr interlayer in the a-C matrix. The tribological properties of Zr/a-C GMFs were defined using a tribometer with a fetal bovine serum (FBS) solution, in which all Zr/a-C GMFs exhibited improved wear resistance, compared to the pure a-C film and Ti alloy. Additionally, Zr/a-C GMFs exhibited the lowest friction coefficient (COF) at 0.114, and a wear rate of 1.47–1.56 × 10−6 mm3/Nm, compared to pure a-C films and Ti alloy. Phase composition and the superior mechanical properties of GMFs were determined as crucial factors contributing to the enhanced wear resistance and low COF in Zr/a-C GMFs. Furthermore, osteoblast cell viability and proliferation on GMF films were tested in cultures, and results indicated that Zr/a-C GMFs have better biocompatibility, compared to Ti alloy. Cell adhesion experiments also demonstrated the excellent biocompatibility and functional reliability of composite biofilms for potential application in bone implants.

Salt Preform Texturing of Absorbable Zn Substrates for Bone-implant Applications.

Surface roughness is an important factor in improving the bone-implant contact area to enhance bone regeneration, yet this aspect has not been applied to absorbable metals. Textured zinc surfaces with varying degrees of surface roughness were produced using a salt-preform method with fine- and coarse-grained salts and compared to a polished control sample. The resulting surfaces were characterized by scanning electron microscopy (SEM), surface roughness, corrosion rates, and in vitro cytotoxicity. The resulting textured surfaces exhibit micron-sized cavities and increased roughness consistent with the initial salt particle size. The corrosion rate was shown to accelerate significantly as compared to the polished control sample, and pre-osteoblasts displayed healthy morphologies on the textures. The results confirm textured zinc surfaces support cell adhesion and can be used to control the corrosion rate. This study represents an important intermediate step that can be applied to porous absorbable metal scaffolds for bone-implant applications.

Hydroxyapatite-Collagen Composite Made from Coral and Chicken Claws for Bone Implant Application

Synthesis of porous hydroxyapatite-collagen composites for bone implant applications has been carried out. Hydroxyapatite synthesized from coral by the precipitation method, while Collagen synthesized from chicken claws. Collagen formation was carried out by freeze-dry technique with variations in freezing time of 2, 4 and 6 hours at -80 ° C. The next process was by drying in a lyophilizer. Characterization of samples was carried out using Fourier Transform Infra Red (FTIR), Scanning Electron Microscopy (SEM), compressive strength test and cytotoxicity test with Microtetrazolium (MTT) assay. FTIR results proved that collagen uptake and hydroxyapatite combine chemically. This is indicated by the absorption of functional groups that did not coincide between collagen and hydroxyapatite functional groups with composites. SEM observations showed that the largest pore size was obtained at freezing for 2 hours which was 774 μm and the smallest in freezing for 6 hours was 640 μm. This pore size was an important parameter of the bone implant because it played a role in the osteoinductive process. The composite compressive strength test results for freezing 2 hours, 4 hours and 6 hours respectively was 737 KPa, 842 KPa and 707.7 KPa. The results of the cytotoxicity test with MTT showed the percentage of cell viability above 100%. This means that the Hydroxyapatite-collagen composite is non-toxic. So, the sample formed has qualified as a bone implant candidate.

Near-eutectic Zn-Mg alloys: Interrelations of solidification thermal parameters, microstructure length scale and tensile/corrosion properties

Zn-Mg alloys are considered to have potential application in bone implants, since both metals are biocompatible and have biodegradable characteristics. Adding Mg to Zn can boost mechanical and corrosion resistances. However, the literature is very limited on quantifying the interrelation of solidification parameters, microstructural features and mechanical/corrosion properties of Zn-Mg alloys. The present study examines the interrelations of alloy Mg content, macrosegregation effects, morphology and scale of the matrix and eutectic phases, nature of intermetallics and tensile and corrosion properties of near-eutectic Zn-Mg alloys. The alloys samples are obtained by unsteady-state directional solidification resulting in a wide range of solidification thermal parameters and microstructures. We examine microstructural features of both dendritic and complex regular eutectic phases. It is shown that the eutectic exhibits a bimodal pattern with neighboring areas of coarse and fine lamellae. Experimental growth laws relating the primary, secondary and eutectic spacings to the solidification cooling rate and growth rate are proposed. Hall-Petch type equations are derived expressing tensile strength and elongation to dendritic and eutectic spacings. Electrochemical parameters determined by polarization curves during corrosion tests and SEM analyses of corroded areas have shown that the alloy having an essentially eutectic microstructure is associated with better corrosion resistance.

Advancement of the artificial amorphous-crystalline structure of laser cladded FeCrMoCB on nickel-free stainless-steel for bone-implants

Abstract This research proposes the development of amorphous-crystalline FeCrMoCB layer as a promising biomaterial for bone-implant applications. The FeCrMoCB amorphous powder was laser cladded on nickel-free stainless-steel (Cronidur30) using three laser specific energies (Es) levels (31.8, 27.5 and 23.4 J/mm2) to attain different amorphous contents. The amorphous-crystalline structure and the microstructure were investigated using X-ray diffraction and scanning electron microscope, respectively. Later, the corrosion rate and the wear rate in simulated body fluids (SBF) were evaluated to investigate the advancement of the artificial amorphous-crystalline structure of laser cladded FeCrMoCB metallic glass (MG) composite via electrochemical corrosion test and pin-on-disc test, respectively. The hardness and Young's modulus (E) were acquired using nanoindentation measurement while the cytocompatibility was evaluated by MTT assay using MC3T3 cell-lines. The material characterization showed that increasing of Es resulted in decreasing the amorphous phase and increasing the crystalline phase. The laser cladded FeCrMoCB MG composite showed significant enhancement of the corrosion and wear resistance in SBF implying longer implant service time. This advancement behavior is not only superior to the uncoated substrate, but also compared to other biomaterials including Zr-based MG, Ti6Al4V, and CoCrMo alloys in SBF. Finally, the FeCrMoCB MG composite showed an acceptable cytocompatibility behavior bringing promising enhanced characteristics for bone-implant material.

Fabrication and characterization of porous scaffolds for bone replacements using gum tragacanth

The practice of bone implants is the standard procedure for the treatment of skeletal fissures, or to substitute and re-establish lost bone. A perfect scaffold ought to be made of biomaterials that duplicate the structure and properties of natural bone. However, the production of living tissue constructs that are architecturally, functionally and mechanically comparable to natural bone is the major challenge in the treatment and regeneration of bone tissue in orthopaedics and in dentistry. In this work, we have employed a polymeric replication method to fabricate hydroxyapatite (HAP) scaffolds using gum tragacanth (GT) as a natural binder. GT is a natural gum collected from the dried sap of several species of Middle Eastern legumes of the genus Astragalus, possessing antibacterial and wound healing properties. The synthesized porous HAP scaffolds were analyzed structurally and characterized for their phase purity and mechanical properties. The biocompatibility of the porous HAP scaffold was confirmed by seeding the scaffold with Vero cells, and its bioactivity assessed by immersing the scaffold in simulated body fluid (SBF). Our characterization data showed that the biocompatible porous HAP scaffolds were composed of highly interconnecting pores with compressive strength ranging from 0.036 MPa to 2.954 MPa, comparable to that of spongy bone. These can be prepared in a controlled manner by using an appropriate binder concentration and sintering temperature. These HAP scaffolds have properties consistent with normal bone and should be further developed for potential application in bone implants.

Surface Mechanoengineering of a Zr-Based Bulk Metallic Glass via Ar-Nanobubble Doping To Probe Cell Sensitivity to Rigid Materials.

In this study, a new materials platform, utilizing the amorphous microstructure of bulk metallic glasses (BMGs) and the versatility of ion implantation, was developed for the fundamental investigation of cell responses to substrate-rigidity variations in the gigapascal modulus range, which was previously unattainable with polymeric materials. The surface rigidity of a Zr-Al-Ni-Cu-Y BMG was modulated with low-energy Ar-ion implantation because of the impartment of Ar nanobubbles into the amorphous matrix. Surface softening was achieved due to the formation of nanobubble-doped transitional zones in the Zr-based BMG substrate. Bone-forming cell studies on this newly designed platform demonstrated that mechanical cues, accompanied by the potential effects of other surface properties (i.e., roughness, morphology, and chemistry), contributed to modulating cell behaviors. Cell adhesion and actin filaments were found to be less established on less stiff surfaces, especially on the surface with an elastic modulus of 51 GPa. Cell growth appeared to be affected by surface-mechanical properties. A lower stiffness was generally related to a higher growth rate. Findings in this study broadened our fundamental understanding concerning the mechanosensing of bone cells on stiff substrates. It also suggests that surface mechanoengineering of metallic materials could be a potential strategy to promote osseointegration of such materials for bone-implant applications. Further investigations are proposed to fine-tune the ion implantation variables in order to further distinguish the surface-mechanical effect on bone-forming cell activities from the contributions of other surface properties.

Development and characterization of a bioglass/chitosan composite as an injectable bone substitute

SiO2-CaO-P2O5 based bioglass (BG) systems constitute a group of materials that have wide applications in bone implants. Chitosan (Cn) is a biocompatible and osteoconductive natural polymer that can promote wound healing. In this study, bioactivity of chitosan/bioglass (CnB) composites as minimally invasive bone regenerative materials was assessed both in vitro and in vivo. Injectability tests and scanning electron microscopy (SEM) results demonstrated the formation of uniform injectable paste-like composites using BG particles and Cn. Fourier transform infrared spectroscopy (FTIR) and SEM images confirmed hydroxyapatite deposition in vitro after incubation in simulated body fluid (SBF). Higher BG content in the composite correlated with increased human osteoblast proliferation. An in vivo study in a rat spinal fusion model confirmed that increasing the amount of BG improved osteoconductivity. Manual palpation, radiographic images and pathological assessments proved that the composites promote bone formation. Based on these data, the synthesized composites have a potential application in orthopedic and reconstructive surgeries as a minimally invasive bone substitute.

Anisotropic Porous Ti6Al4V Alloys Fabricated by Diffusion Bonding: Adaption of Compressive Behavior to Cortical Bone Implant Applications

In this work, porous Ti6Al4V alloys with 30%–70% porosity for biomedical applications were fabricated by diffusion bonding of alloy meshes. Pore structure was characterized by Micro-CT and SEM. Compressive behavior in the out-of-plane direction and biocompatibility with cortical bone were studied. The results reveal that the fabricated porous Ti6Al4V alloys possess anisotropic structure with square pores in the in-plane direction and elongated pores in the out-of-plane direction. The average pore size of porous Ti6Al4V alloys with 30%–70% porosity is in the range of 240–360 µm. By tailoring diffusion bonding temperature, aspect ratio of alloy meshes and porosity, porous Ti6Al4V alloys with different compressive properties can be obtained, for instance, Young's modulus and yield stress in the ranges of 4–40 GPa and 70–500 MPa, respectively. Yield stress of porous Ti6Al4V alloys fabricated by diffusion bonding is close to that of alloys fabricated by rapid prototyping, but higher than that of fabricated by powder sintering and space-holder method. Diffusion bonding temperature has some effects on the yield stress of porous Ti6Al4V alloys, but has a minor effect on the Young's modulus. The relationship between compressive properties and relative density conforms well to the Gibson–Ashby model. The Young's modulus is linear with the aspect ratio, while the yield stress is linear with the square of aspect ratio of alloy meshes. Porous Ti6Al4V alloys with 60%–70% porosity have potential for cortical bone implant applications.

Bactericidal Coatings for Bone Implant Applications

Infections after bone implant surgeries have remained one of the leading underlying cause of revision surgery due to implant failure. Despite careful and improved surgery procedures and systemic antibiotic prophylaxis are well practised, the possibility of infection still exists. Many strategies have been studied to prevent post-implant infections, such as anti-bacterial coatings, adhesion resistant coatings, and anti-microbial alloying element. To respond on the challenge of reducing the risks of infections after bone implantations, a review that focused on the effectiveness of anti-bacterial coatings on metallic implants are briefly presented.

Growth factors-loaded calcium phosphate/polymer hybrid coating with sequential release behavior prepared via electrochemical deposition method

Abstract In this study, the dicalcium phosphate dehydrate (DCPD)/carboxymethyl hexanoyl chitosan (CHC) hybrid coating layer with sequential release of BMP-2 and TGF-β1 was deposited onto Ti6Al4V substrate by electrochemical co-precipitation method. Different concentrations of amphiphatic chitosan derivative (carboxymethyl hexanoyl chitosan, CHC), BMP-2 and TGF-β1-loaded PLA microspheres (PLA/TGF-β1 MSs) were co-precipitated with the precursor of DCPD. The resulting DCPD/CHC hybrid coating incorporated with BMP-2 and PLA/TGF-β1 MSs was designed for improving the osteoconductive and osteoinductive functionalities of Ti6Al4V. FTIR spectroscopy and X-ray diffraction were used to characterize these hybrid coatings. The drug release profile, MC3T3-E1 cell proliferation and alkaline phosphatase activity were used to investigate the functionality of these hybrid coatings. It was found that the incorporation of CHC could be used as a mean to manipulate the release behavior of growth factor from the DCPD/CHC hybrid coating. In addition, the BMP-2- and PLA/TGF-β1 MSs-incorporated DCPD/CHC hybrid coating exhibited a sequential release of BMP-2 and TGF-β1 during the first and second two weeks, respectively. Importantly, the DCPD/CHC hybrid coating immersed in simulated body fluid gradually transformed to hydroxyapatite phase. Hence, the BMP-2 and PLA/TGF-β1 MSs-incorporated DCPD/CHC hybrid coating exhibited the best cell viability and the highest ALP activity after 14 days. The biocompatible hybrid coating with sequential release functionality proposed in the present study can enhance the osseointegration process and possess promising potential for clinical applications in bone implants and tissue engineering.

Anisotropic porous titanium with superior mechanical compatibility in the range of physiological strain rate for trabecular bone implant applications

Porous titanium for biomedical application was fabricated by diffusion bonding of titanium meshes. Compressive mechanical compatibility and strain rate sensitivity were studied in the range of physiological strain rate under quasi-static and dynamic conditions. The results show that porous titanium presents anisotropic pore structure suited for bone ingrowth. Quasi-static compressive Young׳s modulus and yield stress are in the range of 0.4–6.5GPa and 5–105MPa, respectively, for porous titanium with 30–70% relative density. Based on the Gibson–Ashby model, quasi-static compressive properties can be quantitatively designed and tailored with respect to relative density to match those of human trabecular bone. Porous titanium with 30–40% relative density compressed in the out-of-plane direction shows excellent mechanical compatibility in strain rate sensitivity, and has huge potential for application in human trabecular bone implants.

Enhancing the bio-corrosion resistance of Ni-free ZrCuFeAl bulk metallic glass through nitrogen plasma immersion ion implantation

Improving the resistance of bulk metallic glass (BMG) to corrosion, particularly pitting, is crucial to the further development of this material. This study employed surface treatment based on nitrogen plasma immersion ion implantation (N-PIII) to enhance the bio-corrosion resistance of Ni-free Zr62.5Cu22.5Fe5Al10 BMG for application in bone implants. Resistance to bio-corrosion was evaluated by establishing potentiodynamic polarization curves in artificial saliva (AS) and simulated body fluid (SBF). Commercial pure Ti was used as the control. Results demonstrate that N-PIII treatment did not alter the bulk amorphous structure of Zr62.5Cu22.5Fe5Al10 BMG. Following N-PIII treatment, a nitride-containing 15nm thick oxide film was formed on the BMG. This film significantly improved resistance to bio-corrosion in both AS and SBF solutions. The N-PIII-treated BMG presented lower corrosion rates (50–67% less) and higher corrosion potential (800–1100mV more) than that observed in untreated BMG and Ti. The N-PIII treatment also significantly improved resistance of the BMG to pitting (increased pitting potential by 500–700mV). This is the first report of the outstanding resistance of Ni-free Zr-based BMG to bio-corrosion (i.e. corrosion rate 0.01μA/cm2; pitting potential >1200mV; corrosion potential >270mV) in simulated biological environments.

Development of Porous Calcium Phosphate Bioceramics for Bone Implant Applications: A Review

The present review briefly outlines the most recent patents and journals on various aspects of porous calcium phosphate bioceramics including techniques of preparation, properties and bone implant applications. Bioactive ceramics are a class of materials that have capability to bond directly with the host bone. These materials can be easily assimilated by the body and are considered to be biodegradable. Researches have revealed that artificial bones made from hydroxyapatite or a combination of hydroxyapatite (HA) and tricalcium phosphate (TCP) is a perfect substitute for natural bone owing to its excellent biocompatibility and properties close to that of human bone. Bioceramics made of HA are available in dense and porous forms. Several efforts on the fabrication of porous calcium phosphate bioceramics have been carried upon in the field of clinical orthopaedics. The realisation of these efforts can be observed from the fact that numerous patents have been filed on methods of preparing porous calcium phosphate bioceramics for bone implant applications. A number of porous HA ceramics have been developed for applications in both tissue engineering and drug delivery systems. Porous bodies are decomposable in human body and provide a surface for proliferation and growth of cells that are infiltrated from the surrounding tissues so that a new bone grows into the pores and prevents any movement or loosening of the implants. Consequently, these can be used for filling the damaged bone, repair of fractured bone and even can be used as hard tissue replacements. Several processing techniques have been employed for fabrication of porous scaffolds. Among prominent techniques are gel casting, slip casting, camphene-based freeze casting and polymeric-sponge method.

One-step synthesis of bioactive glass by spray pyrolysis

Bioactive glasses (BGs) have recently received more attention from biologists and engineers because of their potential applications in bone implants. The sol–gel process is one of the most popular methods for fabricating BGs, and has been used to produce BGs for years. However, the sol–gel process has the disadvantages of discontinuous processing and a long processing time. This study presented a one-step spray pyrolysis (SP) synthesis method to overcome these disadvantages. This SP method has synthesized spherical bioactive glass (SBG) and mesoporous bioactive glass (MBG) particles using Si-, Ca- and P-based precursors. This study used transmission electron microscopy, selected area electron diffraction and X-ray dispersive spectroscopy to characterize the microstructure, crystallographic structure, and chemical composition for the BG particles. In addition, in vitro bioactive tests showed the formation of hydroxyl apatite layers on SBG and MBG particles after immersion in simulated body fluid for 5 h. Experimental results show the SP formation mechanisms of SBG and MBG particles.