Nanosilicon carbide/hydroxyapatite nanocomposites: structural, mechanical and in vitro cellular properties

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

The goal of this review is to present a wide range of hybrid formulations and composites containing calcium orthophosphates (abbreviated as CaPO4) that are suitable for use in biomedical applications and currently on the market. The bioactive, biocompatible, and osteoconductive properties of various CaPO4-based formulations make them valuable in the rapidly developing field of biomedical research, both in vitro and in vivo. Due to the brittleness of CaPO4, it is essential to combine the desired osteologic properties of ceramic CaPO4 with those of other compounds to create novel, multifunctional bone graft biomaterials. Consequently, this analysis offers a thorough overview of the hybrid formulations and CaPO4-based composites that are currently known. To do this, a comprehensive search of the literature on the subject was carried out in all significant databases to extract pertinent papers. There have been many formulations found with different material compositions, production methods, structural and bioactive features, and in vitro and in vivo properties. When these formulations contain additional biofunctional ingredients, such as drugs, proteins, enzymes, or antibacterial agents, they offer improved biomedical applications. Moreover, a lot of these formulations allow cell loading and promote the development of smart formulations based on CaPO4. This evaluation also discusses basic problems and scientific difficulties that call for more investigation and advancements. It also indicates perspectives for the future.

Enhanced toughness and strength of 3D printed carbide-oxide composite for biomedical applications

Natural materials derived/extracted Ceramics is an excellent material for developing ceramic-based orthopedic implants. Recently, we have demonstrated an easily scalable, energy-efficient green method to extract ceramic particles from bio-waste i.e. chicken bone. Though the chicken bone extract (CBE) has good biocompatibility, it lacks good mechanical properties in the 3D printed condition as that of human bones. Here, we have reinforced CBE with different weight proportions of silicon carbide to improve the mechanical characteristics of the composite. The hybrid of CBE (oxide) and carbide (SiC) is sintered at different temperatures to understand the effect of the interface of the two ceramics. It is observed that temperature has minimal effect and composition has a noticeable effect on mechanical strength as well as bio-toxicity. The toughness (∼3.58 MJ/m3) and compressive strength (∼64.64 MPa) of the 90:10 composition sintered at 1250 °C show the maximum optimum values. A mathematical model has also been developed to predict and correlate the toughness with porosity, volumetric loading, and elastic modulus of the 3D-printed ceramic composite.

Improved dispersion of SiC whisker in nano hydroxyapatite and effect of atmospheres on sintering of the SiC whisker reinforced nano hydroxyapatite composites

In order to improve the mechanical properties of nano hydroxyapatite (HA), silicon carbide whisker (SiC_w) with excellent mechanical and biological properties was used as the reinforcement for SiC whisker reinforced nano hydroxyapatite (SiC_w/HA) composites. Hydrothermal synthesis method was adopted to prepare the uniformly dispersed SiC_w and HA composite powders, and SiC_w/HA composites were fabricated by pressureless sintering. The interfacial bonding state and mechanical properties of SiC_w/HA composites in different sintering atmospheres (air and N₂) were systematically investigated. The results show that the uniformity of the composite powders decreases with the increase of SiC_w content, and the cross-section of SiC_w/HA composites gradually changes from glossy and smooth to rough and undulate. When the content of SiC_w is 15 wt%, the maximum bending strength and fracture toughness of the composites sintered in air atmosphere (HAW15) are 40.85 MPa and 1.82 MPa·m^1/2 respectively, which are higher than those of pure HA. Compared with those of the SiC_w/HA composites sintered in N₂ atmosphere, the bending strength and fracture toughness of the HAW15 composites are increased by 154.2% and 10.3%, respectively. Moreover, Simulated body fluid (SBF) and in vitro cell behavior tests indicate that the SiC_w/HA composites still have excellent bioactivity. The possible strengthening and toughening mechanisms of SiC_w/HA composites are that the dispersion of SiC_w in HA matrix is improved by hydrothermal process, and the interfacial bonding property is enhanced because of the reaction fusion on interface of SiC_w/HA composites during sintering in air atmosphere. The adoption of hydrothermal process improves the dispersion uniformity of SiC_w in HA matrix. When sintering in air atmosphere, the interfacial bonding property of SiC_w/HA composite is enhanced via the reaction fusion (SiO₂ is formed by the oxidation of SiC_w). Both of them lead to the increase of strength and toughness of the composites. This study would provide additional insights into the feasibility of SiC_w/HA composites as load-bearing implant materials in orthopedic applications.

Proliferation and osteogenic differentiation of rat BMSCs on a novel Ti/SiC metal matrix nanocomposite modified by friction stir processing

The aims of this study were to fabricate a novel titanium/silicon carbide (Ti/SiC) metal matrix nanocomposite (MMNC) by friction stir processing (FSP) and to investigate its microstructure and mechanical properties. In addition, the adhesion, proliferation and osteogenic differentiation of rat bone marrow stromal cells (BMSCs) on the nanocomposite surface were investigated. The MMNC microstructure was observed by both scanning and transmission electron microscopy. Mechanical properties were characterized by nanoindentation and Vickers hardness testing. Integrin β1 immunofluorescence, cell adhesion, and MTT assays were used to evaluate the effects of the nanocomposite on cell adhesion and proliferation. Osteogenic and angiogenic differentiation were evaluated by alkaline phosphatase (ALP) staining, ALP activity, PCR and osteocalcin immunofluorescence. The observed microstructures and mechanical properties clearly indicated that FSP is a very effective technique for modifying Ti/SiC MMNC to contain uniformly distributed nanoparticles. In the interiors of recrystallized grains, characteristics including twins, fine recrystallized grains, and dislocations formed concurrently. Adhesion, proliferation, and osteogenic and angiogenic differentiation of rat BMSCs were all enhanced on the novel Ti/SiC MMNC surface. In conclusion, nanocomposites modified using FSP technology not only have superior mechanical properties under stress-bearing conditions but also provide improved surface and physicochemical properties for cell attachment and osseointegration.

Calcium Orthophosphate-Containing Biocomposites and Hybrid Biomaterials for Biomedical Applications

The state-of-the-art on calcium orthophosphate (CaPO4)-containing biocomposites and hybrid biomaterials suitable for biomedical applications is presented. Since these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration, this subject belongs to a rapidly expanding area of biomedical research. Through the successful combinations of the desired properties of matrix materials with those of fillers (in such systems, CaPO4 might play either role), innovative bone graft biomaterials can be designed. Various types of CaPO4-based biocomposites and hybrid biomaterials those are either already in use or being investigated for biomedical applications are extensively discussed. Many different formulations in terms of the material constituents, fabrication technologies, structural and bioactive properties, as well as both in vitro and in vivo characteristics have been already proposed. Among the others, the nano-structurally controlled biocomposites, those containing nanodimensional compounds, biomimetically fabricated formulations with collagen, chitin and/or gelatin, as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using CaPO4-based biocomposites and hybrid biomaterials in the selected applications are highlighted. As the way from a laboratory to a hospital is a long one and the prospective biomedical candidates have to meet many different necessities, the critical issues and scientific challenges that require further research and development are also examined.

Investigating the addition of SiO2–CaO–ZnO–Na2O–TiO2 bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity

Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2–CaO–ZnO–Na2O–TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560 ℃ with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability.

Hot Isostatic Pressing (HIPing) of FeCralloy®-Reinforced Hydroxyapatite

The goal of this study was to produce hydroxyapatite (HAp), a bioactive biomaterial, in a decomposition-free form with fracture toughness comparable to bone by metal fibre-reinforcement. This goal was ultimately achieved. Glass encapsulation of FeCralloy®-reinforced HAp was an unsuccessful technique due to the excessive low-temperature volatilisation, which aerated the glass. Therefore a graphite/stainless steel encapsulation system was used in the present study. Hot isostatic pressing enabled the production of fully dense decomposition-free HAp with toughness improvements of 14 times (FeCralloy® fibres, optimally 15 vol%), comparable to cortical bone. Further, it was found that the HAp decomposition temperature was higher at 100 MPa (the HIPing pressure) than for pressureless sintering. Addition of the FeCralloy® fibre additive induced significant plastic deformation and ductile fracture of the hydroxyapatite.

Hydroxyapatite Matrix Composites by Hot Isostatic Pressing: Part 1. Alumina Fibre Reinforced

Fracture Toughness Improvement of the Hydroxyapatite Matrix Composite, to a Level Comparable to that of Natural Bone for in Vivo Applications, Was the Aim of the Present Work. Hot Isostatic Press Using a Graphite/stainless Steel Encapsulation System Enabled the Production of Fully Dense Decomposition-Free Hap with Toughness Improvements of: 2.4 Times (Al2O3 Fibres, Optimally 20 Vol%). Glass Encapsulation of Fibre-Reinforced Hap Resulted in Aeration from Sample Volatilization. Further, it Was Found that the Hap Decomposition Temperature Was Higher at 100 Mpa (the Hiping Pressure) than for Pressureless Sintering. the Toughening Effect of the Al2o3 Fibre Additive Induced Plastic Deformation and Ductile Fracture.

Biocomposites and hybrid biomaterials based on calcium orthophosphates

The state-of-the-art of biocomposites and hybrid biomaterials based on calcium orthophosphates that are suitable for biomedical applications is presented in this review. Since these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration, this subject belongs to a rapidly expanding area of biomedical research. Through successful combinations of the desired properties of matrix materials with those of fillers (in such systems, calcium orthophosphates might play either role), innovative bone graft biomaterials can be designed. Various types of biocomposites and hybrid biomaterials based on calcium orthophosphates, either those already in use or being investigated for biomedical applications, are extensively discussed. Many different formulations, in terms of the material constituents, fabrication technologies, structural and bioactive properties as well as both in vitro and in vivo characteristics, have already been proposed. Among the others, the nanostructurally controlled biocomposites, those containing nanodimensional compounds, biomimetically fabricated formulations with collagen, chitin and/or gelatin as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using biocomposites and hybrid biomaterials based on calcium orthophosphates in the selected applications are highlighted. As the way from the laboratory to the hospital is a long one, and the prospective biomedical candidates have to meet many different necessities, this review also examines the critical issues and scientific challenges that require further research and development.