Search

Novel bone substitutes such as highly porous ceramic scaffolds can serve as platforms for delivering active molecules. A common problem is to control the release of the drug, therefore, it is beneficial to use a drug-functionalized polymer coating. In this study, β-tricalcium phosphate-based porous scaffolds were obtained and coated with diclofenac-functionalized biopolymer – poly(3-hydroxyoctanoate) – P(3HO). To the best of our knowledge, studies using P(3HO) as a component in ceramic-polymer based drug delivery system for bone tissue regeneration have not yet been reported. Presented materials were comprehensively investigated by various techniques such as powder X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, hydrostatic weighing and compression tests, pH and ionic conductivity measurements, high-performance liquid chromatography and in vitro cytotoxicity studies. The obtained diclofenac-loaded composite was not only characterised by controlled and sustained drug release, but also possessed improved mechanical properties. Moreover, the precipitation of apatite-like forms on its surface was observed after incubation in simulated body fluid, which indicates its bioactive potential. After 24 hours no cytotoxic effect on MC3T3-E1 mouse preosteoblastic cells was confirmed using indirect cytotoxicity studies. Thus, this promising multifunctional composite scaffold can be a promising candidate as an anti-inflammatory drug-delivery system in bone tissue engineering.

A novel way of obtaining highly porous cements is foaming them with the use of nonionic surface active agents (surfactants). In this study, foamed calcium phosphate cements (fCPCs) intended for in situ use were fabricated by a surfactant-assisted foaming process. Three different surface active agents, Tween 20, Tween 80 and Tetronic 90R4, were used. The amount of surfactant, based on its critical micelle concentration and cytotoxicity as well as foaming method, was determined. It has been established that in order to avoid cytotoxic effects the concentration of all applied surfactants in the cement liquid phases should not exceed 1.25 g L−1. It was found that Tetronic 90R4 had the lowest cytotoxicity whereas Tween 20 had the highest. The influence of the type of surfactant used in the fabrication process of bioactive macroporous cement on the physicochemical and biological properties of fCPCs was studied. The obtained materials reached higher than 50 vol% open porosity and possessed compressive strength which corresponds to the values for cancellous bone. The highest porosity and compressive strength was found for the material with the addition of Tween 80. In vitro investigations proved the chemical stability and high bioactive potential of the examined materials.

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.

In this paper, novel hybrid biomicroconcrete-type composites were developed and investigated. The solid phase of materials consisted of a highly reactive α -tricalcium phosphate (α-TCP) powder, hybrid hydroxyapatite-chitosan (HAp-CTS) material in the form of powder and granules (as aggregates), and the polysaccharides sodium alginate (SA) or hydroxypropyl methylcellulose (HPMC). The liquid/gel phase in the studied materials constituted a citrus pectin gel. The influence of SA or HPMC on the setting reaction, microstructure, mechanical as well as biological properties of biomicroconcretes was investigated. Studies revealed that manufactured cement pastes were characterized by high plasticity and cohesion. The dual setting system of developed biomicroconcretes, achieved through α-TCP setting reaction and polymer crosslinking, resulted in a higher compressive strength. Material with the highest content of sodium alginate possessed the highest mechanical strength (~17 MPa), whereas the addition of hydroxypropyl methylcellulose led to a subtle compressive strength decrease. The obtained biomicroconcretes were chemically stable and characterized by a high bioactive potential. The novel biomaterials with favorable physicochemical and biological properties can be prosperous materials for filling bone tissue defects of any shape and size.

Polylactide (PLA), widely used in bioengineering and medicine, gained popularity due to its biocompatibility and biodegradability. Natural origin and eco-friendly background encourage the search of novel materials with such features, such as polyhydroxyoctanoate (P(3HO)), a polyester of bacterial origin. Physicochemical features of both P(3HO) and PLA have an impact on cellular response 32, i.e., adhesion, migration, and cell morphology, based on the signaling and changes in the architecture of the three cytoskeletal networks: microfilaments (F-actin), microtubules, and intermediate filaments (IF). To investigate the role of IF in the cellular response to the substrate, we focused on vimentin intermediate filaments (VIFs), present in mouse embryonic fibroblast cells (MEF). VIFs maintain cell integrity and protect it from external mechanical stress, and also take part in the transmission of signals from the exterior of the cell to its inner organelles, which is under constant investigation. Physiochemical properties of a substrate have an impact on cells’ morphology, and thus on cytoskeleton network signaling and assembly. In this work, we show how PLA and P(3HO) crystallinity and hydrophilicity influence VIFs, and we identify that two different types of vimentin cytoskeleton architecture: network “classic” and “nutshell-like” are expressed by MEFs in different numbers of cells depending on substrate features.

Development of new composite materials for bone tissue engineering is a constantly growing field of medicine. Therefore there is a continuous need in creating novel materials that can not only regenerate the defected tissue but also nourish it while the healing process progresses. Here we present a novel type of composite material that fulfils these requirements. The study describes creation of a composite with macroporous bioceramic core that is infiltrated with a thin biopolymer layer. The ceramic component, namely tricalcium phosphate (TCP), due to its mechanistic and bioactive properties may promote new bone creation as shown through the in vitro studies. To the best of our knowledge the coating layer was created for the first time from a representative of bacterially derived medium chain length polyhydroxyalkanoate polymers (mcl-PHA), namely polyhydroxyoctanoate (PHO). This polymer layer not only profoundly changed the stress-strain characteristics of the bioceramic foam but also released ( R )-3-hydroxyacids and their dimers/trimers to the investigated environment. In the manuscript we have in depth characterised these materials employing a set of basic procedures, through 3D structure reconstruction and finishing with prolonged in vitro experiments.

Nowadays, regenerative medicine faces a major challenge in providing new, functional materials that will meet the characteristics desired to replenish and grow new tissue. Therefore, this study presents new ceramic-polymer composites in which the matrix consists of tricalcium phosphates covered with blends containing a chemically bounded diclofenac with the biocompatible polymer&mdash, poly(3-hydroxyoctanoate), P(3HO). Modification of P(3HO) oligomers was confirmed by NMR, IR and XPS. Moreover, obtained oligomers and their blends were subjected to an in-depth characterisation using GPC, TGA, DSC and AFM. Furthermore, we demonstrate that the hydrophobicity and surface free energy values of blends decreased with the amount of diclofenac modified oligomers. Subsequently, the designed composites were used as a substrate for growth of the pre-osteoblast cell line (MC3T3-E1). An in vitro biocompatibility study showed that the composite with the lowest concentration of the proposed drug is within the range assumed to be non-toxic (viability above 70%). Cell proliferation was visualised using the SEM method, whereas the observation of cell penetration into the scaffold was carried out by confocal microscopy. Thus, it can be an ideal new functional bone tissue substitute, allowing not only the regeneration and restoration of the defect but also inhibiting the development of chronic inflammation.

Recently, intensive efforts have been undertaken to find new, superior biomaterial solutions in the field of hybrid inorganic&ndash, organic materials. In our studies, biomicroconcretes containing hydroxyapatite (HAp)&ndash, chitosan (CTS) granules dispersed in an &alpha, tricalcium phospahate (&alpha, TCP) matrix were investigated. The influence of CTS content and the size of granules on the physicochemical properties of final bone implant materials (setting time, porosity, mechanical strength, and phase composition) were evaluated. The obtained materials were found to be promising bone substitutes for use in non-load bearing applications.

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 ± 8 MPa) than the one with methylcellulose (17 ± 4 MPa) and the one lacking polymer (14 ± 4 MPa). All the developed materials exhibited high bioactivity in vitro.

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 + , Mg 2+ and Mg 2+ /CO 3 2- 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 Mg 2+ and sulphate ions (II) chemical interaction between Mg 2+ 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.

Implantations in orthopedics are associated with a high risk of bacterial infections in the surgery area. Therefore, biomaterials containing antibacterial agents, such as antibiotics, bactericidal ions or nanoparticles have been intensively investigated. In this work, silver decorated β tricalcium phosphate (βTCP)-based porous scaffolds were obtained and coated with a biopolymer—poly(3-hydroxybutyrate)-P(3HB). To the best of our knowledge, studies using silver-doped βTCP and P(3HB), as a component in ceramic-polymer scaffolds for bone tissue regeneration, have not yet been reported. Obtained materials were investigated by high-temperature X-ray diffraction, X-ray fluorescence, scanning electron microscopy with energy dispersive spectroscopy, hydrostatic weighing, compression tests and ultrahigh-pressure liquid chromatography with mass spectrometry (UHPLC-MS) measurements. The influence of sintering temperature (1150, 1200 °C) on the scaffolds’ physicochemical properties (phase and chemical composition, microstructure, porosity, compressive strength) was evaluated. Materials covered with P(3HB) possessed higher compressive strength (3.8 ± 0.6 MPa) and surgical maneuverability, sufficient to withstand the implantation procedures. Furthermore, during the hydrolytic degradation of the composite material not only pure (R)-3-hydroxybutyric acid but also its oligomers were released which may nourish surrounding tissues. Thus, obtained scaffolds were found to be promising bone substitutes for use in non-load bearing applications

The implant-related infections are a severe problem in orthopedic surgery. In this work, bone cements based on α-TCP, silver doped hydroxyapatite and calcite were examined. Developed bioactive materials revealed good surgical handiness and appropriate setting times allowing for their application. In order to assess antibacterial properties, two independent experiments (test imitating in vivo conditions and test of cumulative extraction) were used. It was found that bone cement matrix do not impede the Ag + release from the Ag-HA agglomerates. Materials showed mild antibacterial activity which depended on the kind of bacterial strain and the type of test. Presence of silver in the tested materials increased the antibacterial activity in the extracts only for E. coli strain and the effect was transient. In the case of Gram-positive strains ( S. aureus and S. epidermidis ), antibacterial activity was most probably connected with the properties of cement material, not with the content of silver. Observed reduction of osteoblast viability in vitro resulted from the synergic effect: decrease in concentrations of Ca 2+ , Mg 2+ , and PO 4 3- ions in the culture medium and the presence of silver ions.

Background 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. Objective 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. Methods 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. Results 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. Conclusions 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 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.

The objective of this study was to combine titanium doped nano-hydroxyapatite with chitosan and calcium sulfate to obtain cement-type materials with improved cohesion and handling properties. It was proven that the presence of nano-TiHA influenced setting, hardening, microstructure and bioactivity of the cement samples. In the developed composites chitosan played a role of the cohesion promotor and created homogenous organic layers on the materials surfaces. Application of chitosan in acetic acid solution favorably delayed setting process of calcium sulfate dihydrate. The polymer combined with nano-TiHA and calcium sulfate improved handling and workability of the cements without diminishing their mechanical properties. It was suggested that the resorption rate of materials based on calcium sulfate can be optimized by addition of both titanium doped nano-hydroxyapatite and chitosan.

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.

In the present study two alpha-tricalcium phosphate powders (αTCP-1 and αTCP-2) were synthesized by slightly different routes. For structural comparison, commercial pure α-TCP (αTCP-st) was used. The influence of the preparation method on physicochemical properties of α-TCP was investigated using scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD). The chemical structure of the samples was determined using spectroscopic methods: mid-infrared spectroscopy (FT-IR), Raman spectroscopy and solid-state nuclear magnetic resonance (ssNMR). Specific surface area of the synthesized αTCP-1, αTCP-2 and standard αTCP-st powders was measured using the BET method with nitrogen adsorption. The studies have shown differences in morphology of the samples. αTCP-1 is characterized by small grains forming agglomerates below 2 µm while the αTCP-2 powder has a tendency to form compact clusters with micropores below 5 µm. Its specific surface area is about 5 times lower than αTCP-1 and close to the reference material. PXRD demonstrated that αTCP-1 is significantly less crystalline. In addition, the crystallinity of αTCP-2 was comparable to that of the standard sample. FT-IR and ssNMR experiments have indicated that αTCP-1 is not homogenous but contains beside alpha-tricalcium phosphate amorphous calcium phosphate (ACP). We suggest that ACP may be found in the interior of agglomerates and therefore it is not converted to a highly crystalline form at higher temperature. Different ways of grinding and heat treatment strongly influence characteristic properties (crystallinity, Ca/P molar ratio, phase composition, specific surface area) of the obtained αTCP.

Composites consisting of hydroxyapatite (HA) and chitosan (CTS) have recently been intensively studied. In this work, a novel inorganic-organic (I/O) HA/CTS materials in the form of granules were prepared through a simple solution-based chemical method. During the synthesis of these hybrids, the electrostatic complexes between positively charged, protonated amine groups of chitosan and the negative phosphate species (HPO42 − and H2PO4−) were formed. Our biocomposites belong to the class I of hybrids, which was confirmed by FTIR studies. XRD analysis revealed that the obtained materials consisted of hydroxyapatite as the only crystalline phase. Homogeneous dispersion of the components in HA/CTS composites was confirmed. The use of 17 wt% and 23 wt% of chitosan resulted in approximately 12-fold and 16-fold increase in the compressive strength of HA/CTS as compared to the non-modified HA material. During incubation of the studied materials in SBF, pH of the solution remained close to the physiological one. Formation of apatite layer on their surfaces indicated bioactive nature of the developed biomaterials.

Nowadays successful regeneration of damaged bone tissue is a major problem of the reconstructive medicine and tissue engineering. Recently a great deal of attention has been focused on calcium phosphate cements (CPCs) as the effective bone fillers. Despite a number of studies regarding CPCs, only a few compare the physicochemical and biological properties of α-TCP based materials of various phase compositions. In our study we compared the effect of several components (calcite, hydroxyapatite doped with Mg2+, CO3 2− or Ag+ ions, alginate, chitosan and methylcellulose) on the physicochemical and biological properties of α-TCP-based bone cements. The influence of materials composition on their setting times, microstructure and biochemical stability in simulated body fluid was determined. A number of in vitro laboratory methods, including ICP-OES, metabolic activity test, time-lapse microscopic observation and SEM observations were performed in order to assess biocompatibility of the studied biomaterials. The positive outcome of XTT tests for ceramic extracts demonstrated that all investigated cement-type composites may be considered cytocompatible according to ISO 10993-5 standard. Results of our research indicate that multiphase cements containing MgCHA, AgHA and calcite combined with αTCP enhanced cell viability in comparison to material based only on αTCP. Furthermore materials containing chitosan and methylcellulose possessed higher cytocompatibility than those with alginate. Graphical abstract

Mineralized hydrogels are increasingly gaining attention as biomaterials for bone regeneration. The most common mineralization strategy has been addition of preformed inorganic particles during hydrogel formation. This maintains injectability. One common form of bone cement is formed by mixing particles of the highly reactive calcium phosphate alpha-tricalcium phosphate (α-TCP) with water to form hydroxyapatite (HA). The calcium ions released during this reaction can be exploited to crosslink anionic, calcium-binding polymers such as the polysaccharide gellan gum (GG) to induce hydrogel formation. In this study, three different amounts of α-TCP particles were added to GG polymer solution to generate novel, injectable hydrogel-inorganic composites. Distribution of the inorganic phase in the hydrogel was studied by high resolution microcomputer tomography (µCT). Gelation occurred within 30 min. α-TCP converted to HA. µCT revealed inhomogeneous distribution of the inorganic phase in the composites. These results demonstrate the potential of the composites as alternatives to traditional α-TCP bone cement and pave the way for incorporation of biologically active substances and in vitro and in vivo testing. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 822-828, 2018.

In this paper we present a complex study on the preparation and characterization of the cement-type implant material composed of α-tricalcium phosphate and chitosan. α-TCP has already been used as an initial component of bone cement formulations. In most cases, however, it was synthesized using a solid state reaction. In our studies, highly reactive α-TCP powder was obtained by a wet chemical method. Chitosan is well known as a safe and biocompatible polymer. In our studies it was used to improve the characteristic of the cements. Chitosan was introduced into the bone cements in the form of acetic acid solution and acted as a binder for agglomerates of calcium phosphate grains but at the same time the impeded creation of interconnections inside the agglomerates. The concentration of acetic acid influenced the pore size distribution. In vitro investigations proved the high bioactive potential of the examined materials.

Following the quest for new composite materials for bone tissue engineering, a novel elastic hydroxyapatite-glucan composite loaded with two aminoglycoside antibiotics was prepared. The porosity of the composite and the drug release profiles in closed-loop and semi-open systems were tested. The antibacterial activity of the drug was estimated against two Gram-positive and two Gram-negative bacterial strains causing orthopedic infections. It was found that the loaded antibiotic acted in a biphasic mode. The majority of the drug was released within 48-119 h in a pore-dependent manner and inhibited the bacterial growth in the culture medium. However, a small residual amount of the drug was bound to the composite microstructure via ionic interactions and acted as a short-lived barrier against bacterial adhesion to the composite, although the surrounding medium was no longer protected against bacterial infection. Sub-inhibitory concentrations of the released drug were observed in the medium only during the last two days of the experiment (minimized risk of occurrence of drug-resistant strains). Thus the novel drug-loaded elastic hydroxyapatite-glucan composite, demonstrating a biphasic mode of antibacterial action, may be recommended for antibiotic prophylaxis in bone substitute implantation, with less emphasis on the treatment of bone infections.

In vitro chemical stability and bioactivity of three different cement type bone substitutes were determined by incubating cement samples in the simulated body fluid (SBF) for 7 and 28 days. Morphology of sample surfaces has been studied using scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectroscopy (EDS) and by atomic force microscopy (AFM). The diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) was applied as a supplementary method. The development of bone-like apatite layers on the surface depended on their initial phase composition. Obtained cements showed good surgical handiness, high bioactive potential and were chemically stable. They seem to be promising materials for bone substitution.

Unsatisfactory surgical handiness is a commonly known disadvantage of implantable granular bioceramics. To overcome this problem, β-1,3-glucan, biotechnologically derived polysaccharide, has been proposed as a joining agent to combine granular ceramics into novel compact and elastic composite. Hydroxyapatite/glucan elastic material was processed and evaluated as a potential bone void filler. The procedure of composite formation was based on gelling properties of glucan. Its properties were studied using X-ray microtomography, SEM-EDS, FTIR spectroscopy, compression test and ultrasonic method. Sorption index was determined in phosphate buffered saline; bioactivity in simulated body fluid; sterility in growth broth and human blood plasma; implantation procedure in dog model. HAp/glucan composite is sterilizable, flexible and self-adapting to defect shape. It exhibits bioactivity, good surgical handiness, high sorption index and profitable mechanical properties, resembling those of spongy bone. Results of pilot clinical experiment on animal (dog) patients of a local clinic of animal surgery suggested good healing properties of the composite and its transformation into new bone tissue within critical-size defect. The results obtained in this study confirm that flexible HAp/glucan composite has potential as a bone-substituting material. Promising results of pilot clinical experiment suggest that further in vivo experiments should be performed.

In order to improve some features of bone substitutes the new self-setting composite-type implant material based on Mg 2+ /CO 3 2− co-substituted hydroxyapatite (Mg-CHA) and calcium sulfate hemihydrate (CSH) was developed. Synthetic hydroxyapatites doped with small amounts of additives found in natural bone ( e.g. Mg 2+ and CO 3 2− ) are regarded as promising components of calcium phosphate bone cements (CPCs). The CPCs, now available on the market, due to low resorption rate are too stable to permit material degradation and are slowly replaced by the newly formed bone. To improve cement resorption we used calcium sulfate which is a well-known biodegradable and biocompatible bone defect filler. Combining properties of Mg-CHA and CSH allowed developing a new, promising, easy shapeable implant material with high potential for bone regeneration.

Hydroxyapatite (HA), magnesium containing hydroxyapatite (Mg-HA) and magnesium containing carbonated apatite (Mg-CHA) were prepared by the wet chemical synthesis. Various analytical methods, such as X-ray diffraction (XRD), infrared spectroscopy (FTIR) and high-resolution solid-state nuclear magnetic resonance (SSNMR) were applied to characterize physicochemical properties of the studied samples. The synthesized apatites were found nanocrystalline with the absence of additional phases. Mg-CHA was less crystalline than the other samples and presented the highest specific surface area. The material had chemical composition and morphological features similar to that of bone mineral. Chemical differences between crystal surface and crystal interior of the analyzed samples (i.e. Mg2+, CO 3 2 - , HPO 4 2 - and water distribution) were discussed.

Hydroxyapatite and magnesium modified hydroxyapatite were deposited on nitrited Ti6Al4V substrates by use of pulsed laser deposition technique. Three target materials consisting of non-modified and magnesium modified hydroxyapatite with Mg content of 0.6 wt.% and 1.8 wt.% were ablated using an ArF excimer laser. The obtained coatings were analyzed using X-ray diffraction, FTIR and AFM methods in order to determine the influence of magnesium on their phase and chemical composition, crystallinity, surface morphology and biological properties. Doping with low concentration of Mg does not significantly influence the HA morphology but improves osteoblast adhesion as compared to pure HA.

Hydroxyapatite (HA) – Ca 10 (PO 4 ) 6 (OH) 2 is a basic inorganic model component of hard biological tissues, such as bones and teeth. The significant property of HA is its ability to exchange Ca 2+ ions, which influences crystallinity, physico-chemical and biological properties of modified hydroxyapatite materials. In this work, FTIR, Raman spectroscopy, XRD, SEM and EDS techniques were used to determine thermal stability, chemical and phase composition of Mn containing hydroxyapatite (MnHA). Described methods confirmed thermal decomposition and phase transformation of MnHA to αTCP, βTCP and formation of Mn 3 O 4 depending on sintering temperature and manganese content. In vitro biological evaluation of Mn-modified HA ceramics was also performed using human osteoblast cells.

Carbonate hydroxyapatite (CHAp) was synthesized by a wet precipitation method. In the synthesis, calcium oxide, H 3 PO 4 and (NH 4 ) 2 HPO 4 were applied as reactants. NH 4 HCO 3 in the amount of 0.05–0.20 mol per 0.3 mol of H 3 PO 4 or (NH 4 ) 2 HPO 4 was used as the source of CO 3 2− groups. Sintering was carried out using powders and uniaxially pressed samples of carbonate and non-carbonate hydroxyapatites. The influence of synthesis conditions as well as sintering atmosphere on sinterability and phase composition of the final ceramic materials was evaluated. It was found that using properly synthesized CHAp powders and CO 2 atmosphere during heat-treatment it was possible to obtain dense CHAp ceramics with 1% of CaCO 3 as the secondary phase at the temperature 300–350 °C lower than that required for non-carbonate hydroxyapatite. Chemical stability and bioactive potential of CHAp–CaCO 3 ceramics were confirmed by in vitro tests.

There is a technological need for highly porous bioceramics to be produced in an environmentally friendly manner. Gel-casting of highly porous HAp-(α-TCP) (CaP) foams using agarose as a gelling agent was investigated. Foaming of gel-cast suspension was performed at the temperature of 60 °C followed by transformation of the foams from a liquid state to a gelled state by cooling them to 15 °C. The sintered (1250 °C, 2 h soaking time) foams were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N 2 adsorption isoterm and Hg porosimetry. XRD study revealed that additives used in the gel-casting process did not influence the phase composition of the investigated materials. The macroporous microstructure of HAp-(α-TCP) foams was typically composed of approximately spherical pores (cells) interconnected by circular windows. The foams exhibited a broad pore size distribution with cells and windows ranging from 250 to 900 μm, and from 25 to 250 μm, respectively. The mode for spherical pore size was approximately 500 μm while the above value for window was ∼100 μm. Additionally, the small amount of wall microporosity in the range of 0.2–0.9 μm was confirmed by SEM and Hg porosimetry. The obtained porous ( P = 90%) HAp-(α-TCP) scaffolds with interesting two types of macropores and a small amount of micropores seem to be a promising bone substitution material.

BACKGROUND: Calcium phosphate ceramics have been widely considered as scaffolds for bone tissue engineering. Selection of the best support for cultured cells, crucial for tissue engineered systems, is still required. OBJECTIVE: We examined three types of calcium phosphate compounds: α-tricalcium phosphate – the most soluble one, carbonate hydroxyapatite – chemically the most similar to the bone mineral and biphasic calcium phosphate – with the best in vivo biocompatibility in order to select the best support for osteoblastic cells for tissue engineered systems. METHODS: Human osteoblasts were tested in direct contact with both dense samples and 3D scaffolds in either static or dynamic culture. Cell viability, cell spreading, osteogenic cell capacity, and extracellular matrix production were examined. RESULTS: The obtained data indicate that biphasic calcium phosphate is the optimal cell-supporting material. In addition, dynamic culture improved cell distribution in the scaffolds, enhanced production of the extracellular matrix and promoted cells osteogenic capacity. CONCLUSIONS: Biphasic calcium phosphate should be recommended as the most suitable matrix for osteogenic cells expansion and differentiation in tissue engineered systems.

Besides high-temperature calcium phosphates (CaPs), low-temperature calcium phosphate bone cements (CPCs), due to excellent biological properties: bioactivity, biocompability and osteoconductivity, are successfully used as bone substitutes. However, some disadvantages, related mainly to their low resorption rate and poor mechanical properties result in limited range of applications of these implant materials to non-loaded places in the skeletal system. To overcome this problem, magnesium phosphate cements (MPCs) with high strength have been considered as biomaterials. The main disadvantage of MPCs is that the acid-base setting reaction is an exothermic process that must be strictly controlled to avoid tissue necrosis. In this work, a new composite bone substitute (Hydroxyapatite Magnesium Phosphate Material - HMPM) based on hydroxyapatite (HA) and magnesium phosphate cement (MPC) with sodium pyrophosphate applied as a retardant of setting reaction was obtained. Its setting time was adequate for clinical applications. Combining properties of HA and MPC has made it possible to obtain microporous (showing bimodal pore size distribution in the range of 0.005-1.700 micrometers) potential implant material showing good surgical handiness and sufficient mechanical strength. Effectiveness of sodium pyrophosphate as a retardant of exothermic setting reaction of the new cement formulation was confirmed. After setting and hardening, the material consisted of hydroxyapatite and struvite as crystalline phases. Unreacted magnesium oxide was not detected.

In the studies undoped HA and HA modified with 0.3; 0.6; 0.9; 1.8 wt % of Mg were prepared by the wet method. Introduction of magnesium into HA structure influenced its thermal stability as well as phase composition, sinterability, microstructure, flexural strength and chemical stability of the obtained calcium-phosphate ceramics. The presence of magnesium promoted the decomposition of HA to βTCP above 800°C. Beyond a certain limit (0.9 wt %), Mg ions caused formation of MgO in Mg-HA ceramics. Chemical stability of Mg modified HA below 0.9 wt % Mg under in vitro conditions was similar to that of the undoped hydroxyapatite. Biological studies showed that the number of cells cultured on the surface of HA samples with 1.8 wt % Mg additive, probably due to the MgO content, was lower than on the pure HA ceramics.

Calcium phosphates (CaPs): hydroxyapatite (HA) and TCP are common biomaterials used in orthopedic, dental and maxillofacial surgery as bone fillers and also as drug carriers. Studies of the β→α TCP transformation and formation of mono-, bi- or three-phase CaPs materials: βTCP-αTCP-HA are of principal importance. Stability of calcium phosphate ceramics depends on many factors. Our dynamic studies by high temperature XRD measurements showed that monoclinic αTCP was a considerably stable phase after its creation completed at 1200°C. Different phase composition was obtained in technological conditions.

The goal of our studies has been to determine under in vitro conditions the amount and rate of pentoxifylline release from the samples of modified hydroxyapatite [HAp-Ca10(PO4)6(OH)2] implants in the form of microporous blocks (heterogeneous system) as well as from hydroxyapatitegypsum pellets (homogeneous system). For the preparation of microporous hydroxapatite ceramics additives of calcium metaphosphate Ca(PO3)2 (5 and 10 wt. %) or hydrated magnesium orthophosphate Mg3(PO4)2·8H2O (10 wt. %) were used as modifiers. In the case of drug release from heterogeneous carriers, cylinders filled with 50 mg of PTX were used. In the homogeneous system the pellets made of HAp and CaSO4·1/2H2O powders with homogeneously incorporated of 50 mg PTX were applied. It has been shown that the process of drug release from multifunctional ceramic implants depends to a significant degree on the microstructure of the materials, and the type of carrier system (heterogeneous or homogeneous).

The main objective of this article is to present the basic stages of creating a computer simulation of medication release from an undegraded carrier. Additionally, an innovative approach was presented to the construction of a porous material used for making the carrier for the medication. The programme presented here is based on Cellular Automata, used as a tool for modelling physical, chemical and biological phenomena which change in time. The results of in-silico calculations have been compared with empirical results.