The use of porous titanium-based implant materials for bone contact has been gaining ground in recent years. Selective laser melting (SLM) is a rapid prototyping method by which porous implants with ...highly defined external dimensions and internal architecture can be produced. The coating of porous implants produced by SLM with ceramic layers based on calcium phosphate (CaP) remains relatively unexplored, as does the doping of such coatings with magnesium (Mg) to promote bone formation. In this study, Mg-doped coatings of the CaP types octacalcium phosphate and hydroxyapatite (HA) were deposited on such porous implants using the pulsed laser deposition method. The coated implants were subsequently implanted in a rabbit femoral defect model for 6 months. Uncoated implants served as a reference material. Bone-implant contact and bone volume in the region of interest were evaluated by histopathological techniques using a tri-chromatographic Masson-Goldner staining method and by microcomputed tomography (µCT) analysis of the volume of interest in the vicinity of implants. Histopathological analysis revealed that all implant types integrated directly with surrounding bone with ingrowth of newly formed bone into the pores of the implants. Biocompatibility of all implant types was demonstrated by the absence of inflammatory infiltration by mononuclear cells (lymphocytes), neutrophils, and eosinophils. No osteoclastic or foreign body reaction was observed in the vicinity of the implants. µCT analysis revealed a significant increase in bone volume for implants coated with Mg-doped HA compared to uncoated implants.
The current studies provide insights into how predictions based on results of physicochemical and in vitro tests are consistent with the results of in vivo studies. The new biomicroconcrete type ...materials were obtained by mixing the solid phase, composed of hybrid hydroxyapatite/chitosan granules and highly reactive α‐tricalcium phosphate powder, used as the setting agent. This approach guaranteed a good adhesion of the continuous cement phase to the surface of granules. It has been demonstrated that developed biomicroconcretes are surgically handy, possessed favorable physicochemical and biological properties and can be considered as effective bone implant material. The hierarchical porosity and compressive strength (2–6 MPa) similar to cancellous bone made them suitable for low‐load bearing applications. Despite the fact that final setting times of biomicroconcretes were longer than recommended in the literature (i.e., exceeded 15 min), their short cohesion time allows for a successful implantation in a rabbit femoral defect model. Histological analysis and Raman studies revealed newly formed bone tissues around the sides of implanted materials. Furthermore, the process of neovascularization and reconstruction of the bone tissue, as well as a reverse scaffolding process, was visible. No signs of inflammation or adverse tissue reactions were observed during the experiment.
The influence of the three nonionic surface active agents such as Tween 20, Tween 80, and Tetronic 90R4 on hydrolysis, setting reaction, microstructure, and mechanical properties of alpha tricalcium ...phosphate (α-TCP) based materials was determined. The study revealed that the addition of any of the surfactants mentioned above slightly prolonged the setting time of the tested cements (up to 5 min). On the other hand, it was found that surfactants influence the long-term hydrolysis reaction. The addition of surfactants also affected the microstructure of the final materials, especially after incubation in a simulated body fluid. Surface active agents also had an impact on mechanical behavior of the obtained cements. Sorbitan esters, Tween 20 and Tween 80, decreased compressive strength in comparison to the reference material (6.56 ± 1.59 MPa) to 3.54 ± 1.18 and 3.68 ± 1.03 MPa, respectively. Interestingly, Tetronic 90R4, never used before as an additive to calcium phosphate bone cements (CPCs) caused a 2-fold increase of this value (up to 13.28 ± 1.59 MPa). All the developed materials exhibited bioactivity in vitro. The obtained results shed new light on surfactants as CPCs additives. They should not only be considered as foaming agent or binders, but also they deserve more attention as modifiers affecting the physicochemical properties of α-TCP based materials.
Material properties of the scaffolds as well as their microstructure are vital in determining in vivo cellular response. Three-dimensional (3D), highly porous scaffolds are used in tissue engineering ...to provide a suitable microenvironment and to support regeneration of bone. Both pore sizes and their architecture, in particular interconnection density, impact functionality of scaffold during its biomedical applications.
In this paper a comparative study of the microstructure of highly porous hydroxyapatite scaffolds produced via gelcasting of foamed slurries and replication of polyurethane sponge were carried out.
Quantitative stereological analysis of the microstructure was conducted using transmission X-ray computed microtomography (μCT) and scanning electron microscopy (SEM). Application of the X-ray microtomography allowed obtaining the 2D cross-sectional images of examined samples, and then the 3D reflection of individual samples.
In our studies we proved that the distribution of pores in HAp bioceramics can be controlled by selection of the manufacturing method. In the case of material produced by the gelcasting method, the porosity of the samples was about ∼78 vol.%, while for the method of replication of the porous organic matrix it was higher ∼84 vol.%. Application of gelcasting method resulted in bioceramics with the macropores ranging from 95 μm to 158 μm (the modal value of 120 μm). Furthermore, micropores of size 34 μm-60 μm - so called "windows", were observed on spherical macropores surfaces. In the case of replication of polyurethane sponge only macropores from 295 μm to 337 μm (the modal value of 300 μm) were obtained. Application of μCT and SEM give more information than classical mercury intrusion porosimetry in studies of porous bioceramics. Developed materials met the criteria for porous bone substitutes.
The results of quantitative description of microstructure allowed determining the differences between porous hydroxyapatite bioceramics obtained via replication of porous organic matrix and gelcasting of foamed slurry. The stereological analysis demonstrated, that bioceramics prepared via gelling of foamed slurry has a lower pore size and grains (1.1-1.9 μm) than the material obtained by the method of replication of polyurethane sponge (2.1-2.3 μm). Based on morphological analysis the porosity of tested materials was determined. In the case of material produce by the gelcasting, porosity of the samples was about ∼78 vol.%, while for method of replication of the porous organic matrix the porosity was higher and constituted ∼84 vol.%. Furthermore, evaluated materials varied in porosity and the pore size distribution. It was stated that the method of gelcasting resulted in hydroxyapatite bioceramics with the macropores diameter (95-158 μm), micropores so called "windows" (34-60 μm) - observed on spherical macropores walls and micropores of size 0.6 μm-1.3 μm, which were visible in sintered areas. When the method of replication of polyurethane sponge was applied only macropores from 295 μm to 337 μm were obtained. The comparable values of shape factors such as elongation, curvature of pours boundary and convexity, confirmed that macropores in both studied series had similar shape.
The effect of the sodium alginate and methylcellulose modifiers on hydrolysis, setting reaction, microstructure, mechanical and in vitro properties of α-TCP based materials was investigated. It was ...found that the presence of sodium alginate impeded α-TCP hydrolysis to hydroxyapatite, which may have a significant influence on resorbability, biodegradation and biological behavior of biomaterials. There were several reasons for these phenomena, such as: (I) the gelation of sodium alginate in the presence of Ca2+, (II) the creation of an organic layer which impedes the diffusion of water molecules to α-TCP and (III) the uptake of water molecules by sodium alginate. The inhibitory effect was not observed for methylcellulose and it was diminished in simulated body fluid. Additionally, it was demonstrated that the examined cements varied in their microstructure, setting times and compressive strengths, depending on the applied kind of a polymer additive. The cement containing sodium alginate had a higher compressive strength (20 ± 8MPa) than the one with methylcellulose (17 ± 4MPa) and the one lacking polymer (14 ± 4MPa). All the developed materials exhibited high bioactivity in vitro.
Hydroxyapatite and carbonate-substituted hydroxyapatite are widely used in bone tissue engineering and regenerative medicine. Both apatite materials were embedded into recently developed ...ceramic/polymer composites, subjected to Simulated Body Fluid (SBF) for 30days and characterized using ATR-FTIR spectroscopic imaging to assess their behaviour and structures. The specific aim was to detect the transition phases between both types of hydroxyapatite during the test and to analyze the surface modification caused by SBF. ATR-FTIR spectroscopic imaging was successfully applied to characterise changes in the hydroxyapatite lattice due to the elastic properties of the scaffolds. It was observed that SBF treatment caused a replacement of phosphates in the lattice of non-substituted hydroxyapatite by carbonate ions. A detailed study excluded the formation of pure A type carbonate apatite. In turn, CO32– content in synthetic carbonate-substituted hydroxyapatite decreased. The usefulness of ATR-FTIR spectroscopic imaging studies in the evaluation of elastic and porous β-glucan hydroxyapatite composites has been demonstrated.
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•Transition phases between two apatites were detected by use of ATR- FTIR spectroscopic imaging.
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•Novel biomicroconcretes based on hybrid HAp/CTS granules, α-TCP and pectins were developed.•Biomicroconcretes possessed excellent injectability, high cohesion and washout ...resistance.•Developed materials can be considered as a dual-setting system.•Type of pectins significantly affect mechanical properties of final materials.•Obtained biomicroconcretes can be considered as novel injectable bone substitutes.
In this work, novel bone substitutes in the form of biomicroconcretes with high surgical handiness and satisfactory mechanical properties were developed. Materials were composed of hybrid hydroxyapatite/chitosan (HAp/CTS) granules as aggregate, α-TCP as a setting phase, and pectin solutions as a liquid phase. Two types of low esterified amidated pectins from citrus peels (CP) and apple pomace (AP) and also two fractions of HAp/CTS granules of size between 300 and 400 µm and 400–600 µm were used. The presence of pectins significantly improved surgical handiness and allowed to obtain injectable biomicroconcretes. Synergistic effect of fast internal crosslinking of low esterified pectins, induced by Ca2+ released from α-TCP, together with setting reaction of highly reactive α-TCP (dual setting system) resulted in excellent cohesion of the final materials. By the use of different type of pectins (AP, CP) one can control mechanical properties of the materials. The results showed that pectins from citrus peels more effectively improved compressive strength. The biomicroconcretes obtained in this work showed great potential for the use as novel bone substitutes, however, they require further studies, especially biological evaluation.
Bioactive, chemically bonded bone substitutes with antibacterial properties are highly recommended for medical applications. In this study, biomicroconcretes, composed of silicon modified (Si-αTCP) ...or non-modified α-tricalcium phosphate (αTCP), as well as hybrid hydroxyapatite/chitosan granules non-modified and modified with gold nanoparticles (AuNPs), were designed. The developed biomicroconcretes were supposed to combine the dual functions of antibacterial activity and bone defect repair. The chemical and phase composition, microstructure, setting times, mechanical strength, and in vitro bioactive potential of the composites were examined. Furthermore, on the basis of the American Association of Textile Chemists and Colorists test (AATCC 100), adapted for chemically bonded materials, the antibacterial activity of the biomicroconcretes against S. epidermidis, E. coli, and S. aureus was evaluated. All biomicroconcretes were surgically handy and revealed good adhesion between the hybrid granules and calcium phosphate-based matrix. Furthermore, they possessed acceptable setting times and mechanical properties. It has been stated that materials containing AuNPs set faster and possess a slightly higher compressive strength (3.4 ± 0.7 MPa). The modification of αTCP with silicon led to a favorable decrease of the final setting time to 10 min. Furthermore, it has been shown that materials modified with AuNPs and silicon possessed an enhanced bioactivity. The antibacterial properties of all of the developed biomicroconcretes against the tested bacterial strains due to the presence of both chitosan and Au were confirmed. The material modified simultaneously with AuNPs and silicon seems to be the most promising candidate for further biological studies.
This study delves into the physicochemical properties of inorganic hydroxyapatite (HAp) and hybrid hydroxyapatite-chitosan (HAp-CTS) granules, also gold-enriched, which can be used as aggregates in ...biomicroconcrete-type materials. The impact of granules' surface modifications with citric acid (CA) or polyethylene glycol (PEG) was assessed. Citric acid modification induced increased specific surface area and porosity in inorganic granules, contrasting with reduced parameters in hybrid granules. PEG modification resulted in a slight increase in specific surface area for inorganic granules and a substantial rise for hybrid granules with gold nanoparticles. Varied effects on open porosity were observed based on granule type. Microstructural analysis revealed increased roughness for inorganic granules post CA modification, while hybrid granules exhibited smoother surfaces. Novel biomicroconcretes, based on α-tricalcium phosphate (α-TCP) calcium phosphate cement and developed granules as aggregates within, were evaluated for compressive strength. Compressive strength assessments showcased significant enhancement with PEG modification, emphasizing its positive impact. Citric acid modification demonstrated variable effects, depending on granule composition. The incorporation of gold nanoparticles further enriched the multifaceted approach to enhancing calcium phosphate-based biomaterials for potential biomedical applications. This study demonstrates the pivotal role of surface modifications in tailoring the physicochemical properties of granules, paving the way for advanced biomicroconcretes with improved compressive strength for diverse biomedical applications.
Rheology of bioceramic bone cements is usually described as properties of ceramic slurries, neglecting the self-setting character of these materials. In our studies calcium sulphate based bone ...cements with Ag+, Mg2+ and Mg2+/CO32- modified hydroxyapatite were investigated. Despite of expectations, it has been proven that the presence of magnesium ions significantly influence the rheological properties of cement pastes. Changes in rheological properties were connected with (I) chemical interactions between Mg2+ and sulphate ions (II) chemical interaction between Mg2+ and chitosan. These effects were not observed for silver additive. Most of the developed calcium sulphate based pastes, except material containing MgHA and chitosan, have been categorized as thick pastes applicable with the spatula. It has been found that the chitosan present around and at the calcium sulphate grains acted as a lubricant and prolong the period of quasi-constant viscosity of the pastes.
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