Akermanite Scaffolds Research Articles

Mechanical and degradation properties of triply periodic minimal surface (TPMS) hydroxyapatite & akermanite scaffolds with functional gradient structure

High porosity and high mechanical strength are both important for bone scaffolds, but they are always contradictory, which can be tackled by reasonable structural design. In this paper, we proposed a series of functional gradient lattice structures with the local porosity increasing continuously from the inside out. Based on the triply periodic minimal surface (TPMS), four types of gradient scaffolds were designed with the same porosity (65%) and fabricated by digital light processing (DLP) technology. Finite element (FE) analysis and compressive tests were conducted to investigate the mechanical property, and degradation test was conducted to investigate the biological property. Results showed that gradient structures can effectively enhance the overall compressive strength at the same porosity level. Scaffolds with exponential structure have the highest compressive strength and elastic modulus, reaching 4.45 ± 0.52 MPa and 0.580± 0.034 GPa respectively, almost twice that of uniform structure. Gradient structure has a trivial effect on degradation performance. The degradation rates of all scaffolds can reach more than 5% after immersing for one day. Surface morphology of distinct parts of a scaffold are almost the same due to the highly connected internal structure. These results confirmed that gradient structure can improve mechanical property while maintaining the degradation rate, which have great advantages in bone scaffold engineering.

Akermanite Scaffolds for Bone Tissue Engineering: 3D Printing Using Polymer Precursor and Scaffold Properties

Akermanite Scaffolds for Bone Tissue Engineering: 3D Printing Using Polymer Precursor and Scaffold Properties

Mechanical and Degradation Properties of Triply Periodic Minimal Surface (Tpms) Hydroxyapatite & Akermanite Scaffolds with Functional Gradient Structure

Mechanical and Degradation Properties of Triply Periodic Minimal Surface (Tpms) Hydroxyapatite & Akermanite Scaffolds with Functional Gradient Structure

Preparation and Characterization of Akermanite/Merwinite Scaffolds for Bone Tissue Repair

The ceramics in the system CaO–MgO–SiO2 has recently attracted a great deal of attention because they display a good in vitro bioactivity and have potential use as bone implants. Biphasic calcium-magnesium-silicate ceramics were prepared by a sol-gel method. The dried gel with chemical composition 3CaO.MgO.2SiO2 was thermally treated at 1200 °C for 2 hrs. The structural behavior of the synthesized ceramics was examined by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Merwinite crystalline phase and akermanite phase were recognized. Then, porous akermanite/merwinite scaffolds were prepared to utilize polymer sponge method and evaluated by employing SEM. Furthermore, bone marrow stromal cells (BMSC) adhesion and proliferation on the scaffolds were evaluated by MTT assay test. Differentiation of the cells was assessed by measuring alkaline phosphatase (ALP) activity. The results demonstrated that BMSC adhered and spread well on akermanite scaffolds and proliferated with the increase in the culture time, and the differentiation rate of osteoblasts on scaffolds was comparable to that on blank culture plate control. Thus, the obtained results presented that the akermanite/merwinite scaffolds deserve attention for bone tissue engineering applications.

Three-Dimensional-Printed Bioceramic Scaffolds with Osteogenic Activity for Simultaneous Photo/Magnetothermal Therapy of Bone Tumors.

For the postoperative treatment of bone cancer, biomaterials should possess an antitumor effect and simultaneous repair ability of bone defects. Compared with single photothermal treatment or magnetothermal treatment, photo/magnetothermal joint treatment represents a more high-efficient strategy to kill tumor cells. In this work, a 3D-printed bioceramic scaffold with a photo/magnetothermal effect was successfully designed and fabricated, which exhibited the function of killing tumor cells and excellent osteogenic bioactivity, via incorporating an Fe element into akermanite (AKT) bioceramics. After doping with ferric elements, the AKT scaffolds possessed significantly enhanced compressive strength and desirable ferromagnetic property. The ferric elements endowed the AKT scaffolds with excellent photo/magnetothermal effects, and hence the scaffolds could efficiently kill tumor cells in vitro under mild laser power density and magnetic field. In addition, the Fe-doped AKT bioceramic scaffolds significantly promoted cell proliferation and osteogenic differentiation of rabbit bone mesenchymal stem cells as compared with the original AKT scaffolds without Fe elements. The results suggest that Fe-doped bioceramic scaffolds with both photo/magnetothermal effect and in vitro osteogenic bioactivity could be a promising biomaterial for the synergistic therapy of bone cancers.

Hierarchically porous 3D-printed akermanite scaffolds from silicones and engineered fillers

The present investigation is dedicated to the manufacturing of reticulated three-dimensional akermanite scaffolds, developed by direct reaction between silica, from the oxidation of a commercial silicone resin and oxide fillers, forming pastes for direct ink writing. Crack-free scaffolds, with dense and regular struts, were due to the use of CaCO3 (micro) and MgO nano-particles as reactive fillers. An excellent phase purity was obtained, with the help of the liquid phase provided by anhydrous sodium borate (Na2B4O7), upon firing. The structure of the scaffolds, finally, was successfully modified by using Mg(OH)2 and hydrated sodium borate: besides macro-porosity from direct ink writing, the new scaffolds exhibited homogenous ‘spongy’ struts (owing to water vapor release in the heating step), with no crack. Both types of scaffolds (with dense or porous struts) exhibited remarkable strength-to-density ratios.

Akermanite reinforced PHBV scaffolds manufactured using selective laser sintering.

Scaffold assisted tissue engineering presents a promising approach to repair diseased and fractured bone. For successful bone repair, scaffolds need to be made of biomaterials that degrade with time and promote osteogenesis. Compared to the commonly used ß-tricalcium phosphate scaffolds, Akermanite (AKM) scaffolds were found to degrade faster and promote more osteogenesis. The objective of this study is to synthesize AKM micro and nanoparticle reinforced poly(3-hydroxybutyrate-co-3-hydroxyvalerate; PHBV) composite scaffolds using selective laser sintering (SLS). The synthesized composite scaffolds had an interconnected porous microstructure (61-64% relative porosity), large specific surface areas (31.1-64.2 mm-1 ) and pore sizes ranging from 303 to 366 and 279 to 357 μm in the normal and lateral direction, respectively, which are suitable for bone tissue repair. The observed hydrophilic nature of the scaffolds and the swift water uptake was due to the introduction of numerous carboxylic acid groups on the scaffold surface after SLS, circumventing the need for postprocessing. For the composite scaffolds, large amounts of AKM particles were exposed on the skeleton surface, which is a requirement for cell attachment. In addition, the particles embedded inside the skeleton helped to significantly reinforce the scaffold structure. The compressive strength and modulus of the composite scaffolds were up to 7.4 and 103 MPa, respectively, which are 149 and 197% of that of the pure PHBV scaffolds. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2596-2610, 2019.

On the synthesis of nanostructured akermanite scaffolds via space holder method: The effect of the spacer size on the porosity and mechanical properties

In the present study, for the first time, the space holder method was used to prepare akermanite scaffolds with high porous structures, high interconnectivity, and high compressive strength, while the role of different spacer sizes on the akermanite scaffold properties was also evaluated. The results showed that the increase in the NaCl particle size which was used as spacer leads to an increase of the pore size and interconnectivity and a decrease of compressive strength. When the size of the spacer was 420–600µm and more than 600µm, a total porosity of 82 and 83% and a compressive strength of 0.86 and 0.82MPa were obtained, respectively. These values are higher than those reported in previously studies and provide a great potential for akermanite to be used as bone substitute in tissue engineering. The in vitro bioactivity of the obtained akermanite scaffolds was also investigated.

A novel and economical route for synthesizing akermanite (Ca2MgSi2O7) nano-bioceramic

Despite the benefits of akermanite, there are limited reports on making powder and dense bulk akermanite (Ca2MgSi2O7) and most articles have focused on building akermanite scaffolds. This study centers on a new and economical route for the synthesis of akermanite bioceramic via high energy ball milling and subsequent sintering of a mixed powders of eggshell (as calcium source), MgO, and SiO2. The mechanisms occurred during akermanite synthesis were carefully investigated. XRD, DTA, FTIR, TGA, SEM, TEM, ICP and EDS were used for analyzing the obtained results. Simulated body fluid (SBF) was also used for assessing in vitro bioactivity of the akermanite samples. According to the results, the method presented in this study can be introduced as a facile method for preparing akermanite samples with a good compressive strength of 210±7MPa. The XRD patterns also indicated that akermanite bioceramic was synthesized after heat treating at 900°C which is very low compared to previous researches. With increasing the sintering time of the akermanite samples and the reduction of the surface porosities, the amount of the formed apatite and also the rate of apatite formation decreased and the compressive strength of the samples increased.

Development of bioceramic bone scaffolds by introducing triple liquid phases

Abstract

Akermanite scaffolds reinforced with boron nitride nanosheets in bone tissue engineering.

Akermanite (AKM) is considered to be a promising bioactive material for bone tissue engineering due to the moderate biodegradability and excellent biocompatibility. However, the major disadvantage of AKM is the relatively inadequate fracture toughness, which hinders the further applications. In the study, boron nitride nanosheets (BNNSs) reinforced AKM scaffolds are fabricated by selective laser sintering. The effects of BNNSs on the mechanical properties and microstructure are investigated. The results show that the compressive strength and fracture toughness increase significantly with BNNSs increasing from 0.5 to 1.0 wt%. The remarkable improvement is ascribed to pull out and grain wrapping of BNNSs with AKM matrix. While, overlapping sheets is observed when more BNNSs are added, which results in the decline of mechanical properties. In addition, it is found that the composite scaffolds possess good apatite-formation ability when soaking in simulated body fluids, which have been confirmed by energy dispersed spectroscopy and flourier transform infrared spectroscopy. Moreover, MG63 osteoblast-like cells and human bone marrow stromal cells are seeded on the scaffolds. Scanning electron microscopy analysis confirms that both cells adhere and proliferate well, indicating favorable cytocompatibility. All the facts demonstrate the AKM scaffolds reinforced by BNNSs have potential applications for tissue engineering.

Toughening and strengthening mechanisms of porous akermanite scaffolds reinforced with nano-titania

Akermanite possesses excellent biocompatibility and biodegradability, while low fracture toughness and brittleness have limited its use in load bearing sites of bone tissue.

Silicon carbide whiskers reinforced akermanite scaffolds for tissue engineering

The poor mechanical properties of akermanite (AKM), especially fracture toughness, limits its applications in bone tissue engineering, although it possesses favorable biological performance. In this research, silicon carbide whiskers (SiCw) are added in order to reinforce AKM scaffolds with controllable porous structures fabricated by selective laser sintering (SLS). The mechanical properties, microstructure and toughening mechanisms are analyzed. The results indicate that the compressive strength and fracture toughness increases with increasing SiCw from 5 to 20 wt.%, and then decreases when more SiCw are incorporated. The strengthening and toughening mechanisms are attributed to interface debonding, whisker fracture and whisker pull-out, and the main fracture mode becomes transgranular fracture. Moreover, the phase composition of SiCw remains constant, confirmed by X-ray diffraction (XRD) analysis. The bioactivity and degradation behaviour of the scaffolds were evaluated by soaking them in simulated body fluid (SBF). The results show that the composite scaffolds with 20 wt.% SiCw exhibits good apatite-mineralization ability and a moderate degradation rate in SBF medium. Moreover, scanning electron microscopy (SEM) analysis, MTT assay and alizarin red staining of human bone marrow stromal cells (hBMSCs) seeded scaffolds confirm the stem cell attachment, viability, proliferation and differentiation on the scaffolds. Thus, the overall study proves that SiCw reinforced AKM scaffolds have the potential to be used in bone tissue engineering.

Microstructure, mechanical properties and in vitro bioactivity of akermanite scaffolds fabricated by laser sintering

Akermanite had attracted great attention due to the favourable mechanical properties and excellent biological performance. In this research, the microstructure and mechanical properties of akermanite scaffolds fabricated via laser sintering under different process conditions were studied and characterized. The results showed that the akermanite particles gradually mixed together, grew up and reached complete densification with the scanning speed decreasing from 450 to 150 mm/min, while micro defects such as air holes occurred at 50mm/min. simultaneously, the compressive strength of the scaffolds went up and then descended, and the optimum value was 5.92 ± 0.41 MPa. The Vickers hardness and fracture toughness increased consistently and then tended to stabilize. X-ray diffraction (XRD) results indicated no new phase appeared under all process conditions. MG-63 cell culture revealed that cell adhesion and proliferation occurred, indicating excellent cytocompatibility of the scaffolds. Moreover, in vitro bioactivity tests showed that the apatite layer formed on the scaffolds and became dense and thick with the increase of soaking time in simulated body fluid (SBF), and this fact was further confirmed by energy-dispersive spectroscopy (EDS).

Development of highly porous scaffolds based on bioactive silicates for dental tissue engineering

Various scaffolding materials, ceramics and especially Mg-based ceramic materials, including akermanite (Ca2MgSi2O7) and diopside (CaMgSi2O6), have attracted interest for dental tissue regeneration because of their improved mechanical properties and controllable biodegradation. The aim of the present work was the synthesis of an Mg-based glass-ceramic, which would be used for the construction of workable akermanite scaffolds. The characterization of the synthesized material was performed by Fourier Transform Infrared Spectroscopy (FTIR) X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). Finally, the apatite forming ability of the scaffolds was assessed by immersion in simulated body fluid. The scaffolds were fabricated by the foam replica technique and were subsequently coated with gelatin to provide a functional surface for increased cell attachment. Finally, SEM microphotographs and FTIR spectra of the scaffolds after immersion in SBF solution indicated the inorganic bioactive character of the scaffolds suitable for the intended applications in dental tissue engineering.

Porous akermanite scaffolds for bone tissue engineering: Preparation, characterization, and in vitro studies

The aim of this study was to develop a bioactive, degradable, and cytocompatible akermanite (Ca2MgSi2O7) scaffold with high porosity and pore interconnectivity. In brief, porous akermanite scaffolds were prepared using polymer sponge method. The porosity and corresponding compressive strength were evaluated. The in vitro degradability was investigated by soaking the scaffolds in Ringer's solution. Hydroxyapatite (HAp)-formation ability of akermantite scaffolds in simulated body fluid (SBF) and the effect of ionic products from the scaffolds dissolution on osteoblasts were investigated. In addition, bone marrow stromal cells (BMSC) adhesion and proliferation on the scaffolds were evaluated. Differentiation of the cells was assessed by measuring alkaline phosphatase (ALP) activity. The results showed that akermanite scaffolds possessed 63.5-90.3% of porosity, with a corresponding compressive strength between 1130 and 530 kPa. The weight loss of the scaffolds and ionic content of the Ringer's solution increased with the increase in soaking time, indicating the degradability of scaffolds. HAp was formed on the scaffolds in SBF and the ionic products from akermanite scaffolds dissolution stimulated osteoblasts proliferation, indicating good in vitro bioactivity. Furthermore, BMSC adhered and spread well on akermanite scaffolds and proliferated with the increase in the culture time, and the differentiation rate of osteoblasts on scaffolds was comparable to that on blank culture plate control. Our results suggested that akermanite scaffolds were bioactive, degradable, and cytocompatible, and might be used as bone tissue engineering materials.