Apatite Layer Research Articles

A low-cost approach to develop silica doped Tricalcium Phosphate (TCP) scaffold by valorizing animal bone waste and rice husk for tissue engineering applications

In the present study Hydroxyapatite (HAp) derived Tricalcium Phosphate (TCP) and Silica (SiO2) based scaffold was successfully fabricated for the first time by effective utilizing various waste such as animal waste bone (AWB) and rice husk (RH) as a source of HAp and SiO2 respectively. Scaffold development involved simple steps comprising of segregation of waste materials followed by sample preparation through die compaction and sintering (1000 °C and 1300 °C). Advanced characterization techniques like XRD, SEM, TEM, and FTIR were employed to study the properties of the waste materials as well as the developed composite scaffold. The presence of silica from RH combines with the HAp during high temperature sintering and initiates the phenomenon of phase transformation of HAp to TCP along with the formation of a glassy phase. The extent of phase transformation increases as the wt% of RH increases. XRD analysis revealed the development of different phases. SEM microstructure shows that the addition of silica restricts the grain growth and supports the formation of crystalline glassy phase termed as Si-TCP. FTIR results confirmed the presence of phosphate, carbonate, and hydroxyl groups in the sintered samples. The porosity of the scaffold was in the range of 34–61% and the compressive strength was up to 4.1 MPa. The SEM images of scaffold dipped in simulated body fluid (SBF) shows formation of apatite layer throughout the surface. The bioactivity of the scaffold was highly influenced by the addition of silica in the HAp matrix. The apatite forming ability of the developed porous was much greater than that of pure HAp for the same incubation period. The obtained properties of the developed scaffold are comparable to that of natural bone. Thus the present work creates an opportunity to use AWB for the development of composite for tissue engineering applications.

Impact of silver on fluorophosphate glasses to improve in vitro bioactivity and antibacterial efficacy

This article discusses the effect of silver oxide (Ag2O) on structural changes, apatite-forming ability, and bioactivity during addition onto the fluorophosphate glass (FPG) network. The foremost objective of silver incorporation on to fluorophosphate glass is to enhance the antibacterial efficacy of glass material which can be widely used as implants to minimize the post-surgical infections. Silver-added fluorophosphate glasses (AFPGs) with composition of 48P2O5–29CaO−(20−x)Na2O–3CaF2−xAg2O (x = 0, 0.3, 0.6, 0.9, and 1.2 mol%) were prepared using conventional glass-melting method followed by rapid quenching technique. The in vitro apatite-forming ability of AFPG was evaluated by immersing the samples in simulated body fluid (SBF) for 21 days. The pH variations of the SBF solution were noted throughout the in vitro study and plotted to estimate dissolution mechanism. The structural properties and compositional estimation of AFPG samples before and after in vitro study were analyzed using X-ray diffractometer, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Cytotoxicity of the prepared AFPG samples was evaluated using MTT assay. The bacteriostatic effect of AFPG samples were studied using different strains of bacteria such as Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, S. epidermidis, and S. mutans. The obtained peaks from XRD analysis at 28.12°, 31.73°, 46.71°, 29.11°, 32.25°, 51.59°, and 67.49° confirm crystalline nature and apatite formation on the glass surface. The attained characteristic FTIR peaks at 560 and 600 cm −1 shows the presence of apatite groups of vibration. The SEM image infers the spherical structure on the glass surface representing the presence of apatite layer and the EDAX graph shows the elemental composition of the prepared glass surface. From the present study, it was noted that glass sample containing 0.9 mol % of Ag2O enhanced apatite formation, was less cytotoxic and showed better antibacterial activity. Thus it can be inferred that AFPG0.9 sample can play a significant role in biomedical applications.

Tailoring degradation of MgZn alloy films with bioinert amorphous carbon

MgZn based amorphous alloy films were composited with diamond-like carbon (DLC) in sputter deposition to tailor their degradation and the related biological properties. Structural and compositional analyses indicate that all the films are amorphous, but the films with intermediate MgZn:C ratio exhibit nanoparticles at surface, cracks, peeling off and electric insulation. Metal carbides are possibly formed during film deposition, and the surface layer is then converted to oxides, hydroxides and carbonates during the ageing in air. After immersion in the simulated body fluid for 2 days, apatite and Mg compounds layer is formed on the alloy and the composite films. Although Cl- ions and microgavlanic coupling can accelerate dissolution of the alloy, the carbon phase effectively delays dissolution of the alloy. The films have good antibacterial activity against E. coli, which comes from the released Mg2+ and Zn2+ ions. The MC3T3-E1 cell test shows that the film with metal elements content of 22.6 at% has the highest alkaline phosphatase activity among the tested samples. The suppressed and lasting dissolution of alloy elements is beneficial for antibacterial activity and osteoblast cell behaviors of the MgZn alloy-DLC films.

Preparation of PVP and betaine biomaterials enriched with hydroxyapatite and its evaluation as a drug carrier for controlled release of clindamycin

In this study, ceramics-polymer materials were developed. The preparation and characteristics of the biomaterials based on hydroxyapatite, polyvinylpyrrolidone and betaine obtained by crosslinking under UV light were described. Additionally, to use the system as a carrier of active substance it was enriched with an antibiotic - clindamycin. Fourier-Transform Infrared Spectroscopy (FT-IR) analysis of pure components and composites was performed, sorption capacity was determined, kinetics of clindamycin release over time was evaluated as well as surface morphology was imaged before and after incubation in biological fluid by Scanning Electron Microscopy (SEM). A strong relationship was observed between the swelling ability of the composites and the amount of clindamycin released. The higher the sorption capacity the more drug is released. Moreover, the appearance of new apatite layers on the surface of the composites was noted after only 14 days of incubation in SBF. Such biomineralization indicates the bioactivity of the materials. The results obtained so far confirm the potential of the materials as a carrier of active substance and in regeneration of bone tissue.

Green Synthesis of Bioactive Hydroxyapatite/Cellulose Composites from Food Industrial Wastes

This work aimed at conversion of worthless indurtial wastes to valuable product. Herein, bioactive composites based on bacterial cellulose (BC) and eggshell or eggshell-derived hydroxyapatite (HAp) were prepared by a green method using Gluconacetobacter xylinum bacteria. The effect of addition of eggshell (BC/Eg) and eggshell-derived HAp (BC/HAp-Eg) on the bacterial cellulose yield, biodegradation and biocompatibility was studied. For comparison, HAp derived from chemical precursors was synthesized (BC/HAp-ch). The resultant composites were characterized by XRD, FTIR, and SEM/EDX. Furthermore, the biodegradation and bioactivity were assessed in SBF, and the cell viability was studied against oral normal cells. The results showed that the productivity of BC applied HAp-derived eggshell (1.83 g/L) was higher than that of using (1.37 g/L). Interestingly, the eggshell was converted to Ca3(PO4)2 during incubation in the bacterial culture medium, while Ca3(PO4)2 was formed as a secondary phase when using either eggshell-derived HAp or chemically-derived. The in vitro bioactivity test in SBF showed that all composites were induced the formation of a bone-like apatite layer on their surface with Ca/P ratio, 1.49, 1.35, and 1.41 for BC/Eg, BC/HAp-ch, and BC/HAp-Eg, respectively, near to the ratio in the natural HAp. Finally, the in vitro cell viability test was confirmed good biocompatibility against the composites. However, at high sample concentration (250 µg/mL), BC/HA-Eg showed the higher cell viability (95.2%) than that of BC/Eg (80.5%) and BC/HA-ch (86.2%). In conclusion, eggshell waste could be used directly with bacterial cellulose to produce bioactive composites without the need to convert it to HAp which reduced the cost of production and thus has a higher economic return. Obiviously, eggshell waste can act as calcium, organic matter source, pH preservation, nuterilizing agent along with potential instead of costly buffering agent in the BC culture medium and further for increased the BC production.

3D-printed Mg-1Ca/polycaprolactone composite scaffolds with promoted bone regeneration

In bone tissue engineering, polycaprolactone (PCL) is a promising material with good biocompatibility, but its poor degradation rate, mechanical strength, and osteogenic properties limit its application. In this study, we developed an Mg-1Ca/polycaprolactone (Mg-1Ca/PCL) composite scaffolds to overcome these limitations. We used a melt blending method to prepare Mg-1Ca/PCL composites with Mg-1Ca alloy powder mass ratios of 5, 10, and 20 wt%. Porous scaffolds with controlled macro- and microstructure were printed using the fused deposition modeling method. We explored the mechanical strength, biocompatibility, osteogenesis performance, and molecular mechanism of the Mg-1Ca/PCL composites. The 5 and 10 wt% Mg-1Ca/PCL composites were found to have good biocompatibility. Moreover, they promoted the mechanical strength, proliferation, adhesion, and osteogenic differentiation of human bone marrow stem cells (hBMSCs) of pure PCL. In vitro degradation experiments revealed that the composite material stably released Mg2+ ions for a long period; it formed an apatite layer on the surface of the scaffold that facilitated cell adhesion and growth. Microcomputed tomography and histological analysis showed that both 5 and 10 wt% Mg-1Ca/PCL composite scaffolds promoted bone regeneration bone defects. Our results indicated that the Wnt/β-catenin pathway was involved in the osteogenic effect. Therefore, Mg-1Ca/PCL composite scaffolds are expected to be a promising bone regeneration material for clinical application. Statement of significanceBone tissue engineering scaffolds have promising applications in the regeneration of critical-sized bone defects. However, there remain many limitations in the materials and manufacturing methods used to fabricate scaffolds. This study shows that the developed Ma-1Ca/PCL composites provides scaffolds with suitable degradation rates and enhanced boneformation capabilities. Furthermore, the fused deposition modeling method allows precise control of the macroscopic morphology and microscopic porosity of the scaffold. The obtained porous scaffolds can significantly promote the regeneration of bone defects.

Synthesis of high-entropy La2B2O7 ceramics with non-equivalent principal elements in B-sites and their CMAS resistance performance

A new method is proposed to predict the formation of high-entropy single-phase oxide with a pyrochlore structure synthesis from non-equivalent principal elements. Based on this concepte, the La2B2O7 (B = Zn2+, Mg2+/Ni2+, Ce4+/Zr4+/Hf4+/Sn4+/Ti4+, W6+, Mo6+) were designed, in which high-entropy La2(ZnMgZrWMo)2O7, La2(ZnMgHfWMo)2O7 and La2(ZnMgSnWMo)2O7 pyrochlore ceramics were successfully prepared by solid-phase sintering. The microstructure of the entropy-stabilized phase was demonstrated using X-ray diffraction and elemental mapping, and the thermal properties including the thermal expansion coefficient and thermal conductivity were analyzed. The results show that La2(ZnMgZrWMo)2O7 has a higher thermal expansion coefficient (13.9 × 10–6 K–1) and lower thermal conductivity (0.8 W/m·K) than its corresponding single-components compound. In addition, La2B2O7 (B = Zn2+, Mg2+, Zr4+/Hf4+/Sn4+, W6+, Mo6+) pyrochlore high-entropy ceramics exhibit good calcium – magnesium – aluminosilicate (CMAS) resistance, the apatite protective layer generated after the reaction of La with CMAS effectively prevents further corrosion. This study suggests a novel method for predicting the formation of high-entropy single-phase oxides of pyrochlore structures and provides a new design concept for anti-CMAS corrosion materials.

Enhancing physicochemical, mechanical, and bioactive performances of monetite nanoparticles reinforced chitosan‐PEO electrospun scaffold for bone tissue engineering

AbstractIn the current work, monetite (DCPA) nanoparticles incorporated chitosan (CH)‐based composite was prepared using by electrospinning technique. A smooth and defect‐free fibrous matrix with an average fiber diameter in the range between 311 ± 13 to 380 ± 28 nm was obtained for 5 wt% (CH‐DCPA5) and 7 wt% DCPA (CH‐DCPA7) containing electrospun scaffolds. The results indicated that the addition of 7 wt% DCPA nanoparticles to chitosan caused an increase in the tensile strength of scaffolds from 6.2 to 12.34 MPa. A slow degradation rate (~37% in 28 days) indicates its suitability for bone tissue regeneration. A study on the biomineralization capability of the electrospun scaffolds after their immersion in simulated body fluid in vitro revealed that the addition of DCPA strongly promoted the deposition of the apatite layer onto electrospun nanofibrous scaffolds. The culture of MG‐63 osteoblast cells on the scaffolds demonstrated that the incorporation of DCPA nanoparticles into the chitosan polymeric matrix helped in the adhesion, spreading, and migration of cells. CH‐DCPA5 and CH‐DCPA7 scaffolds exhibited a higher capacity to proliferate osteoblast cell lines as compared to pure CH scaffold as confirmed by MTT assay and qualitative cell viability analysis from fluorescence microscopy. Immunocytochemistry analysis for osteocalcin expression revealed a higher capacity of DCPA‐containing scaffolds to differentiate MG‐63 cells into bone lineage as compared to pure chitosan scaffolds. DCPA incorporation into chitosan also resulted in MG‐63 cultured on to it to elicit higher alkaline phosphatase activity suggesting the highest capacity of CH‐DCPA7 to differentiate MG 63 cell line among all the scaffolds studied here. The results indicated superior osteogenic properties of DCPA nanoparticle reinforced chitosan matrix for use in BTE in the form of nanofibrous scaffolds.

Biological characterization of the zinc-modified hydroxyapatite coated by a pulsed laser deposition method

Pure Hydroxyapatite (Ca10(PO4)6(OH)2) and Zn-HA nanoparticles were successfully deposited on steel substrates, and laser ablation was performed by the pulsed laser deposition (PLD) technique using an Nd: YAG laser (λ = 532 nm, τ = 12 ns). The bioactivity of the thin film was investigated by its immersing in a simulated body fluid solution of pH 7.4 at 37 °C for incubation of 14 days. The growth of the apatite layer after immersion was studied. The analysis showed the formation of needle-like crystals after immersion in solution. Wettability angles decreased for the HA coating after post-deposition compared to pure HA coatings at room temperature and ion substitutions in bioceramics lead to wettability modification. The findings confirm that Zn doping with different concentrations improved antibacterial activity. The results demonstrate that coating the surface with bioactive materials modified with metal ions, yields good biological responses, and varied compositions differentially affect the water contact angles as well as HA layer growth.

Characterization and Evaluation of Composite Biomaterial Bioactive Glass-Polylactic Acid for Bone Tissue Engineering Applications.

The limitations associated with the clinical use of autographs and allografts are driving efforts to develop relevant and applicable biomaterial substitutes. In this research, 3D porous scaffolds composed of bioactive glass (BG) obtained through the sol-gel technique and polylactic acid (PLA) synthesized via lactic acid (LA) ring-opening polymerization were prepared by the gel-pressing technique. Two different weight compositions were evaluated, namely, BG70-PLA30 and BG30-PLA70. The structure and morphology of the resulting scaffolds were analysed by FTIR, XRD, SEM, and under ASTM F1635 standard characterizations. The results confirmed that BG promotes the formation of a hydroxy-carbonated apatite (HAp) layer on composites when immersed in simulated body fluid (SBF). Biodegradability evaluations were carried out according to the ISO 10993-13:2010 standard. In addition, electrochemical evaluations were performed in both Hank’s and SBF solutions at 37 °C in order to analyse the degradation of the material. This evaluation allowed us to observe that both samples showed an activation mechanism in the early stages followed by pseudo-passivation due to physical bioactive glass characteristics, suggesting an improvement in the formation of the HAp nucleation. The described composites showed excellent resistance to degradation and outstanding suitability for bone tissue engineering applications.

Synthesis and characterization of nanohydroxyapatite (nHAp) from Meretrix Meretrix Clam shells and its in-vitro studies for biomedical applications

Recycling of massive waste into valuable products promotes two in one advantages of waste recovery and a pollution-free environment. Preparation of Nanohydroxyapatite (nHAp) and its polymer composites using waste sea shells (natural precursor) are effectively useful in making artificial bone implants, bone cement, and toothpaste additives. The present work is focused to obtain nHAp with good crystalline nature and better biocompatibility using Meretrix Meretrix Clam shells as raw materials by the Co-precipitation method. To enhance the physio-chemical properties, polymers were used as capping agents. The functional group, particle size, thermal stability, phase transition, surface morphology, and electronic transition of atoms of the synthesized samples have been analyzed by spectrographic tools such as FT-IR, XRD, TG/DTA, FESEM/EDAX, XPS and HR-TEM with EDAX mapping respectively. Furthermore, the bacterial sensitivity of the sample against bacteria, the efficiency of the sample towards the formation of an apatite layer over the surface and its hemocompatibility nature were studied by antibacterial, SBF analysis and hemolysis assay respectively. This method of synthesis is free from hard chemicals and harmful by-products. Thus, the report of the present study suggests that it is promising to achieve nHAp with enhanced surface modification which indirectly promotes bone-bonding capability with natural living bone.

Synthesis of Hydroxyapatite/Bioglass Composite Nanopowder Using Design of Experiments.

Composite scaffolds of hydroxyapatite (HAp) nanoparticles and bioactive glass (BG) were applied as an appropriate selection for bone tissue engineering. To this end, HAp/BG composite was synthesized by a hydrothermal method using Design of Experiments (DOE) with a combined mixture–process factor design for the first time. The input variables were hydrothermal temperature at three levels (i.e., 100, 140, 180 °C) as a process factor and two mixture components in three ratios (i.e., HAp 90, 70, 50; BG 50, 30, 10). The degree of crystallinity and crystal size in the composite were the output variables. XRD showed that only a small fraction of BG was crystallized and that a wollastonite phase was produced. The XRD results also revealed that incorporation of Si into the HAp structure inhibited HAp crystal growth and restricted its crystallization. The FTIR results also showed that the intensity of the hydroxyl peak decreased with the addition of silicon into the HAp structure. DOE results showed that the weight ratio of the components strongly influenced the crystal size and crystallinity. SEM and FTIR results identified the greatest bioactivity and apatite layer formation in the Si-HAp sample with an HAp70/BG30 ratio after 14 days immersion in simulated body fluid (SBF) solution, as compared to other ratios and HAp alone. Therefore, the combination of HAp and BG was able to yield a HAp/BG composite with significant bioactivity.

Polydopamine constructed interfacial molecular bridge in nano-hydroxylapatite/polycaprolactone composite scaffold

Nano-hydroxylapatite (nano-HAP)/polycaprolactone (PCL) composite scaffold is proved to possess great potential for bone tissue engineering application since the biocompatibility of PCL and the osteoinduction ability of nano-HAP. However, the interfacial bonding between nano-HAP and PCL is weak by reason of the difference in thermodynamic properties. Herein, nano-HAP was modified by polydopamine (PDA) and then added to the PCL matrix to enhance their interface bonding in bone scaffold manufactured by selective laser sintering (SLS). The results indicated that PDA acted as an interfacial molecular bridge between PCL and nano-HAP. On one hand, the amino groups of PDA formed hydrogen bonding with the hydroxyl groups of nano-HAP, and on the other hand, the catechol groups of PDA formed hydrogen bonding with the ester groups of PCL. Compared with the HAP/PCL scaffolds, the tensile and compressive strength of the P-HAP/PCL scaffolds loading 12 wt% P-HAP were increased by 10% and 16%, respectively. Meanwhile, the scaffold possessed great bioactivity and cytocompatibility that could accelerate the formation of apatite layers and promote the cell adhesion, proliferation and differentiation.

Assessing Mg/Si3N4 biodegradable nanocomposites for osteosynthesis implants with a focus on microstructural, mechanical, in vitro corrosion and bioactivity aspects

Magnesium-based biodegradable implant materials for the osteosynthesis process (fixation or stabilizing of a fractured bone) are on the verge of being used clinically. However, the rapid degradation of magnesium-based materials in the physiological environment results in a loss of mechanical integrity before the complete healing of the fracture site. To address this issue, the present study used Silicon Nitride (Si3N4) nanoparticles to improve the in-vitro degradation resistance along with the mechanical strength and ductility of Magnesium. The Si3N4 nanoparticles were homogeneously reinforced in the pure Magnesium matrix through the ultrasonic-assisted stir casting method. Moreover, the effect of Si3N4 nanoparticles on microstructure, mechanical, in-vitro corrosion and bioactivity response of Mg/Si3N4 nanocomposites was studied. Notably, the inclusion of 1.0 vol% Si3N4 nanoparticles increased tensile strength by 1.4 times and ductility by two times. In addition, the elastic modulus of Mg/Si3N4 nanocomposites is within the range of local cortical bone elastic modulus. In-vitro immersion experiments in simulated physiological fluids revealed a 2.2-fold reduction in degradation rate compared to pure Magnesium. Moreover, the addition of Si3N4 nanoparticles enhanced the in-vitro bioactivity, as the surface of the nanocomposites showed a high needle-like Ca–P apatite layer with a 1.41 Ca/P ratio of the deposited layer close to hydroxyapatite's Ca/P ratio (1.64). Overall, this study provides the basis for the fabrication of stable yet completely biodegradable Mg/Si3N4 nanocomposite bone implants for the osteosynthesis process.

Hydroxyapatite nanoparticles in situ grown on carbon nanotube as a reinforcement for poly (ε-caprolactone) bone scaffold

The incorporation of carbon nanotubes (CNT) and hydroxyapatite (HA) into biopolymer as bone scaffold is expected to combine the excellent mechanical properties of CNT and bioactivity of HA. However, the dispersion of CNT and HA in biopolymer is a challenge. In this paper, under the condition of hydrothermal reaction, HA nanoparticles were in situ synthesized on the surface of carboxyl multi-walled CNT to prevent their aggregation in poly (ε-caprolactone) (PCL) scaffold prepared by selective laser sintering (SLS). The mechanism of in situ synthesis of HA nanoparticles was that the carboxyl functional groups of cCNT acted as anchor sites for Ca2+ deposition, and then Ca2+ attracted HPO42− via electrovalent bonding to in situ nucleation and synthesis of HA nanocrystals. The results demonstrated that HA nanoparticles ranged from about 10 to 30 nm in diameter and 40–80 nm in length were homogeneously generated on the surface of cCNT. Compared with the pure PCL scaffold, the scaffold with contenting of 12% cCNT-HA was increased by 86.6% and 31.9% in tensile and compressive strength, respectively. The strengthening mechanisms could be explained from the bridging and pulling out of the cCNT-HA. Meanwhile, the mineralization experiment results demonstrated that the Ca/P ratio of apatite layer formed on the surface of the PCL/12% cCNT-HA scaffold was 1.66, which was close to that of human bone tissue, indicating the scaffold possessed good bioactivity for inducing the formation of apatite mineralization. Besides, the scaffolds displayed good cytocompatibility for cell attachment, growth and proliferation.

Zinc substituted hydroxyapatite/silk fiber/methylcellulose nanocomposite for bone tissue engineering applications

Fibrous bio-composite based on silk fiber (SF), methylcellulose (MC) and zinc substituted hydroxyapatite (ZnxCa5-x (PO4)3(OH) (x = 0.1, 0.2, 0.5 and 1.0)) were obtained with the use of electrospinning (E-Spin) method. XRD, FTIR, SEM-EDAX, swelling, porosity and mechanical properties of the composites were analyzed. The elongation at break (%) (20.97–317.20 %) and tensile strength (29.85–110.92 MPa) of nanocomposites was increased with an increase in the wt% of Zn-HAP in SF/MC. An increase in the zone of inhibition with an increase in the wt% of Zn-HAP into the SF/MC was observed against E. coli (34 ± 0.33 to 47 ± 1.15), S. aureus (28 ± 0.24 to 38 ± 1.32) and C. albicans (24 ± 0.36 to 39 ± 2.36). The in-vitro biomineralization study using SBF (simulated body fluid) showed apatite layer formation on the nano-composite. In addition, the optimized (20 wt % of Zn1.0Ca4.0(PO4)3(OH)/SF/MC) nano-composite showed good cell viability against human bone osteosarcoma (MG-63) cells.

Bioactive calcium phosphate foam ceramics modified by biomimetic apatite

By combining the method of replication of polyurethane foam matrices at 1200 °C and modification in model SBF (Simulated Body Fluid) solutions of various compositions, open-pore calcium phosphate foam ceramics with a porosity of 53-60 % was obtained. The architecture and morphology of the calcium phosphate foam ceramics surface was formed by using polyurethane foam matrices («Granufoam», «STR») with different porosity and quantity of open pores. Modification of the calcium phosphate foam ceramics in SBF solutions of various compositions leads to a slight decrease in porosity to 3 %, which indicates the formation of an ultrathin apatite layer. The calcium phosphate-modified foam ceramics consisted of β-tricalcium phosphate, β-calcium pyrophosphate, α-tricalcium phosphate, and biomimetic apatite. In the standard SBF solution, the formation of apatite on calcium phosphate foam ceramics occurs slowly (14-56 days) and the strength increases by a factor of 2 as compared to the initial one. Soaking of calcium phosphate foam ceramics in SBF without HCO3- leads to the formation of biomimetic apatite with inclusions of calcium chloride dihydrophosphate in spherulites. Modification in a 5-fold concentrated SBF solution for 3-5 days at 37 °C makes it possible to form 6-10 times more biomimetic apatite compared to standard SBF with a 2.5-fold increase in static strength to 0.05 MPa. It has been established that at 800 °C biomimetic apatite crystallizes into β- tricalcium phosphate.

Fabrication of bioactive poly(ether ether ketone) by laser melt infiltration of poly(ether ether ketone) inside the strontium apatite coatings

A versatile method to immobilize apatite nanoparticles onto PEEK substrate by using CO2 laser was demonstrated. Various strontium apatites were synthesized and dispersed in ethanol at a low concentration of citric acid. This dispersion of strontium apatites was coated on the surface of the PEEK substrate. The apatite-coated PEEK substrate was subsequently irradiated by CO2 laser with repeated multiple scanning mode. The surface temperature was monitored in real time and controlled at approximately the melting point of PEEK. The thermally fixed apatite coatings were unified with the PEEK substrate and unable to separate off. Dissolution of apatite layer in dilute acid solution revealed highly rugged surface morphologies of the PEEK substrate hidden inside the apatite coatings. From these observations we concluded that the heat-fixed apatite layer consisted of nanocomposite of apatite and PEEK. We propose a possible mechanism for the laser bonding processes of this apatite coating, that is, when the coating surface is irradiated by a CO2 laser with rapid periodic scanning mode, this irradiation initiates periodic temperature change with thermal expansion of the air on top of the apatite layer and may induce a photoacoustic effect on them, which may generate pressure waves to hold down the apatite matrix to the PEEK substrate. The heat on the apatite matrix also initiates melting of the adjacent PEEK surface and the melted PEEK polymer intrudes into the voids of the apatite matrix by capillary forces to produce nanocomposite of them. This surface-selective formation of PEEK/apatite nanocomposites on the PEEK substrate may be seen as an alternative method to the conventional surface coatings or various PEEK composite materials.The bioactivity of the apatite-coated PEEK substrate was affirmed through biomimetic deposition of calcium phosphate from simulated body fluid and dissolution behaviors of the apatite coatings in water was also evaluated.

Study the Growth of Apatite Layer on Biodegradable Glass as Bioactive Scaffolds

Bioglass offers a variety of uses for tissue engineering due to its good biocompatibility and chemical composition, similar to a mineral portion of the body. The synthesis of bioglass 13-93 scaffold was achieved by salt leaching technique, and potassium chloride (KCl) was used as porogen with particle sizes of (200-250) μm. Then, sintering to 750 ◦C for around 1 hour was performed. The resultant materials were examined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). They were immersed in a solution of simulated body fluids (SBF) for 7 and 14 days, respectively. Initially, calcium phosphate was created. After 7 and 14 days, the surface comprised of developed crystalline apatite. The bioactivity of scaffolds that were created and examined. The FTIR, SEM, and XRD experiments were done before and after immersion of the sample in SBF. The results showed that the scaffolds contained open and interconnected pores with porosities ranging between (75-78%). The maximum value of compressive strength of the prepared scaffold was about 5.6MPa. Based on the obtained results, the glass scaffolds can be considered promising for bone defects and replacement applications

Deposition of bioactive glass coatings based on a novel composition containing strontium and magnesium

In this work a novel bioactive glass composition was used to deposit coatings by means of plasma spraying. Different coatings were manufactured and optimized by varying the processing parameters and were studied by X-ray diffraction and scanning electron microscopy. Moreover, the bioactivity was assessed by in vitro tests in Simulated Body Fluid solution.The coatings displayed the typical microstructure of atmospheric plasma sprayed coatings, that is a coating made up by the stacking of melted splats, with different thicknesses, porosities and crystalline phases depending on the spraying parameters used. The work showed that all the coatings are denser and with less porosity than those observed for plasma sprayed coatings of the well-known 45S5 bioactive glass, with similar particle size deposited under the same spraying conditions. The in vitro tests demonstrated the bioactive aptitude of all the coatings, on whose surface an hydroxycarbonate apatite layer formed after 7 days of soaking.