β-TCP Phase Research Articles

The experimental and theoretical investigation of Sm/Mg co-doped hydroxyapatites

This study presents an extensive experimental and theoretical analysis of Mg-doped hydroxyapatite (HAp) samples with additional Sm doping at varying amounts. A wet chemical method was used to synthesize Mg-containing HAps at a constant amount of 0.133at.%, and in addition the second dopant of Sm was utilized at varying amounts of 0.133,0.266,0.399,0.532, and 0.665at.%. All of these samples were investigated experimentally and theoretically by using the X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA), in-vitro cell viability tests, and density functional theory (DFT) calculations. The bandgap energy was found to have reduced from 4.6115 eV to 4.3870 eV. The linear attenuation (or absorption) coefficient increased as the amount of Sm in the sample increased, and this parameter decreased as the photon energy increased for all samples. Both the lattice parameter and the theoretical density increased, whereas the unit cell volume and the lattice parameters declined. The XRD and FTIR results revealed that the HAp phase (over 98 percent for all samples) was a major phase formed, while the β-TCP phase (beta-tricalcium phosphate) was a minor phase. The β-TCP phase increased from 0.91to1.57 percent with an increasing amount of Sm. The volume of the unit cell trended in the same direction as predicted by the obtained results theoretically. Increased anisotropic energy density and a decrease in crystallinity have been observed. All samples were found to be thermally stable. Due to the presence of Sm content, cell viability was observed to be affected.

Fibroblasts Mediate Ectopic Bone Formation of Calcium Phosphate Ceramics.

Heterogeneity of fibroblasts directly affects the outcome of tissue regeneration; however, whether bioactive ceramics regulate bone regeneration through fibroblasts is unclear. Ectopic bone formation model with biphasic calcium phosphate (BCP) implantation was used to investigate the temporal and spatial distribution of fibroblasts around ceramics. The effect of BCP on L929 fibroblasts was evaluated by EdU assay, transwell assay, and qRT-PCR. Further, the effect of its conditioned medium on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was confirmed by ALP staining. SEM and XRD results showed that BCP contained abundant micro- and macro-pores and consisted of hydrogen-apatite (HA) and β-tricalcium phosphate (β-TCP) phases. Subsequently, BCP implanted into mice muscle successfully induced osteoblasts and bone formation. Fibroblasts labelled by vimentin gathered around BCP at 7 days and peaked at 14 days post implantation. In vitro, BCP inhibited proliferation of L929 fibroblast but promoted its migration. Moreover, expression of Col1a1, Bmp2, and Igf1 in L929 treated by BCP increased significantly while expression of Tgfb1 and Acta did not change. ALP staining further showed conditioned media from L929 fibroblasts treated by BCP could enhance osteogenic differentiation of BMSCs. In conclusion, fibroblasts mediate ectopic bone formation of calcium phosphate ceramics.

Study of microstructural and electrical properties of silver substituted hydroxyapatite for drug delivery applications

Silver doped hydroxyapatites (Ag-HAp) [Ca10−xAgx(PO4)6(OH)2;(0.0 ≤x ≤ 1.0)] were synthesized with pH = 10, by the in-situ hydrothermal method. Structural, microstructural, compositional, electrical and biocompatibility properties of Ag-Hap samples were studied to ascertain the suitability of the experimental samples in drug-delivery applications. The Rietveld refinement of the X-ray diffraction (XRD) pattern, analysis of Fourier transform infrared (FTIR) spectra, X-Ray photoelectron (XPS) spectra, and Energy Dispersive X-Ray (EDAX) spectra of the Ag-HAp samples had confirmed the successful doping of Ag atoms in the HAp lattice and simultaneous growth of secondary β-TCP phase with the detailed chemical phase compositions of appropriate percentages. The Field Emission Scanning Electron Microscopy (FESEM), EDAX, and Brunauer–Emmett–Teller (BET) characterizations were carried out to study their morphological, compositional, surface, and porous behavior. The cytocompatibility of the laboratory-synthesized biomaterials with sensitive human embryonic kidney cells (HEK293) by in-vitro MTT assay testing revealed that the Ag-HAp powders had no toxic effect on living body-cells up to the safe limit of usage (≤15 μg/mL). The relative cell-viability percentage (%rcv) was evaluated to be 95–106% for highly doped samples. The incorporation of monovalent Ag ions within HAp lattice influenced the thermal hopping of the charge carriers and resulted in significantly high ionic conductivity with very low activation energy for higher temperatures. The significantly high dielectric permittivity for elevated temperatures (613 K) of the Ag-HAp compared to that of pure-HAp, and the considerable amount of interfacial polarization occurring within highly-conductive grain (~10−5Sm−1) and resistive grain-boundary as established by complex impedance study gave rise to the probability of occurrence of the quasi-permanent surface potential with promising specific surface area (~40 m2/g). The highly biocompatible Ag-HAp rods, with good dielectric and electrical properties, showed a huge possibility of the material being used as a nano-carrier for electric field-induced targeted drug delivery purposes in the future.

Bioperformance Studies of Biphasic Calcium Phosphate Scaffolds Extracted from Fish Bones Impregnated with Free Curcumin and Complexed with β-Cyclodextrin in Bone Regeneration.

Fish bones are a natural calcium phosphate (CaP) sources used in biomaterials production for bone regeneration. CaP scaffolds can be enriched with other substances with biological activity to improve bone repair. This study aimed to evaluate the physicochemical properties and bone regeneration potential of biphasic calcium phosphate (BCP) scaffolds impregnated with free curcumin (BCP-CL) or complexed with β-cyclodextrin (BCP-CD) compared to BCP scaffolds. Rietveld’s refinement showed that BCP is composed of 57.2% of HAp and 42.8% of β-TCP and the molar ratio of Ca/P corresponds to 1.59. The scaffolds presented porosity (macro and microporosity) of 57.21%. Apatite formation occurred on the BCP, BCP-CL, and BCP-CD surface, in vitro, in SBF. Micro-Raman technique showed a reduction in the dissolution rate of β-TCP in the curcumin-impregnated scaffolds over time, and in vivo studies on critical-size defects, in rat calvaria, had no additional regenerative effect of BCP-CL and BCP-CD scaffolds, compared to BCP scaffolds. Despite this, the study showed that curcumin impregnation in BCP scaffolds prolongs the release of the β-TCP phase, the BCP- phase with the higher osteoinductive potential, representing an advantage in tissue engineering.

Synthesis and Characterization of Calcium Phosphate Materials Derived from Eggshells from Different Poultry with and without the Eggshell Membrane.

Calcium phosphate materials such as hydroxyapatite (HA) or tricalcium phosphate (β-TCP) are highly attractive due to their multitude of applications in bone replacement as well as their environmental and ecological credentials. In this research, quail, hen, duck, and pigeon eggshells were used as a calcium source to obtain calcium phosphate materials via the environmentally friendly wet synthesis. Using the eggshells with the organic membrane, the biphasic calcium phosphate materials composed mainly of HA were obtained. The second mineral phase was β-TCP in the case of using quail, hen, and pigeon eggshells and octacalcium phosphate (OCP) in the case of duck eggshells. The HA content in the obtained materials depended on the amount of membrane in the eggshells and decreased in the order of pigeon, duck, hen, and quail eggshells. The eggshell membrane removal from the eggshells caused the reduced content of HA and the presence of the more soluble β-TCP or OCP phase in the obtained materials. The calcium ions release profile in the PBS buffer indicates the potential biomedical application of these materials.

Sr,Mg co-doping of calcium hydroxyapatite: Hydrothermal synthesis, processing, characterization and possible application as dentin substitutes

The aim of this study was to investigate the influence of binary Sr, Mg ion-doping compared to the single-ion doping effects on the phase composition and morphology of hydrothermally obtained calcium hydroxyapatite (HAP) powders and on the phase composition, microstructure, and mechanical properties of the sintered materials. Additionally, the focus of this study was to investigate the possible utilization of the binary doped Sr,Mg-HAP compacts as dentin substitutes in restorative dentistry by evaluating their bonding ability with commercially available restorative materials using the shear bond strength test (SBS). The hydrothermally obtained mono-doped Mg5 and Sr5 showed the monophasic apatite structure, while in all co-doped samples β-TCP phase was formed, resulting in biphasic calcium phosphate (BCP) powders. It was confirmed that co-doping with Sr and Mg ions led to the thermal stabilization of the β-TCP phase by suppressing the phase transition into α-TCP when sintered at 1200 °C. Moreover, the co-presence of Mg ions significantly improved the hardness of Sr-doped HAP from 3.74 to 5.02 GPa. Sr,Mg-HAP dental inserts were found to achieve sufficient bonding (13.53 MPa) through the micromechanical interlocking with Z250 dental composite and Single Bond Universal dental adhesive applied with a total etch approach. The SBS values obtained for the SrMg-HAP insert were similar to the literature data on bonding ability with human dentin, indicating that binary doped Sr,Mg-HAP ceramics present a promising material for application in restorative dentistry as dentin substitutes.

Sintering behavior and mechanical properties of hydroxyapatite ceramics prepared from Nile Tilapia (Oreochromis niloticus) bone and commercial powder for biomedical applications

In this work, Nile tilapia (Oreochromis niloticus) bone was calcined at 800 °C for 5 h in an air atmosphere to obtain hydroxyapatite powder (FB powder). The elemental composition, phase structure, and morphology of the FB powder were investigated and compared with commercial hydroxyapatite powder (SM powder). The FB-powder exhibited 1.01 at. % of Mg while the SM-powder showed Mg in ppm-level. Carbonate groups were detected in the two powders. Both HAp and β-tricalcium phosphate (β-TCP) structures were found in the FB powder, but the SM powder exhibit only the HAp phase. Irregular-shaped particles were observed in the FB powder. After the two HAp powders were sintered at 1200 °C and 1250 °C for 2 h (FB-1200, FB-1250, SM-1200, and SM-1250), the β-TCP intensity peaks of the FB-ceramic samples significantly increased with increasing sintering temperature. The highest relative density, well-packed grains, and β-TCP stabilization by Mg at the Ca5 site of the FB-1250 structure were the dominant factors governing the highest mechanical properties. Although high density was observed in the SM-1200 sample, Vickers hardness of the SM-1200 sample is lower than the FB-1250 sample. This may be attributed to the partial decomposition of HAp into β-TCP, α-tricalcium phosphate (α-TCP), and Ca10(PO4)6O phases. In addition, the increase of grain size was the main factor that governs the increasing compressive strength and Young's modulus instead of density and phase decomposition of the SM-ceramic samples.

Investigation of Antibacterial Activity and Cell Viability of Ag/Mg and Ag/Zn Co-doped Hydroxyapatite Derived from Natural Limestone.

Improving the antibacterial activity to avoid infections and keeping the biocompatibility at a safe level of HAp-based materials is highly important for biomedical applications. In this work, we investigate the antibacterial activity of 2.5Ag/2.5Mg co-doped HAp and 2.5Ag/2.5Zn co-doped HAp toward Escherichia coli bacteria. Moreover, their biocompatibility for osteoblastic cells (MC3T3-E1 cells) was also evaluated. The physical properties were characterized with necessary characterization tools such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller. Both 2.5Ag/2.5Mg and 2.5Ag/2.5Zn co-doped HAp consist of hydroxyapatite (HAp) and beta calcium triphosphate (β-TCP) phases. The antibacterial test reveals that 2.5Ag/2.5Mg co-doped HAp or 2.5Ag/2.5Zn co-doped HAp has an outstanding antibacterial activity with a killing rate of 99 ± 1%. More importantly, the cell viability for osteoblast cells with 2.5Ag/2.5Mg and 2.5Ag/2.5Zn co-doped HAp promotes the proliferation much more effectively than 2.5Ag-doped HAp or 5Ag-doped HAp.

Incorporation of 45S5 bioglass via sol-gel in β-TCP scaffolds: Bioactivity and antimicrobial activity evaluation

In this work, β-TCP (β-tricalcium phosphate) bioresorbable scaffolds were prepared by the gel casting method. Then, they were impregnated with a 45S5 bioglass sol gel solution to improve biocompatibility and promote bioactivity and antimicrobial activity. The β-TCP scaffolds had an apparent porosity of 72%, and after the incorporation of the bioglass, this porosity was maintained. The elements of the bioglass were incorporated into β-TCP matrix and there was a partial transformation from the β-TCP phase to the α-TCP (α-tricalcium phosphate) phase, besides the formation of bioactive calcium and sodium‑calcium silicates. The scaffolds β-TCP with 45S5 bioglass incorporated (β-TCP/45S5) did not show a reduction in their values of mechanical strength and Weibull modulus, despite the partial transformation to the α-TCP phase. Bioactivity, cell viability, and antimicrobial activity improved significantly for the β-TCP/45S5 scaffold comparing to the scaffold without the bioglass. The mineralization of carbonated hydroxyapatite was verified in Simulated Body Fluid (SBF). The cell viability, evaluated by the reduction of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide – MTT in MG63 cells, increased by 178%, and β-TCP/45S5 scaffold also enhanced cell activity and osteoblast differentiation observed by means of total protein contend and alkaline phosphatase activity, respectively. The formation of growth inhibition zones was also observed in the disk diffusion assay for three tested microorganisms: Staphylococcus aureus, Escherichia coli and Candida albicans. To conclude, the vacuum impregnation method in 45S5 bioglass sol gel solution was effective in penetrating all the interconnected macroporosity of the scaffolds and covering the surface of the struts, which improved their biological properties in vitro, bioactivity and antibacterial activity, without reducing mechanical strength and porosity values. Thus, the β-TCP/45S5 scaffolds are shown as potential candidates for use in tissue engineering, mainly in bone tissue regeneration and recovery.

Effect of pH level and calcination on the production of calcium phosphates by acidic route of wet precipitation

Multiphasic calcium phosphate powders were synthesized by the acidic route, using lactic acid as a chelating agent that allows the production of a stable and rich solution of calcium and phosphate ions at room temperature. After pH adjusting, without varying the concentrations of precursor solution, XRD and FTIR analyses showed different CaP phases before and after heat treatment at 1000 °C. At pH 5, brushite plate-like particles were produced, while at higher pH levels (7 to 12) nano-hydroxyapatite particles were formed. After the calcination process, partial and total decomposition of hydroxyapatite in the β-TCP phase was explained by XRF analysis due to the calcium-deficient hydroxyapatite of synthesized samples at pH 7 and 10. This work presents an important method to synthesize any desired CaP phase compositions by varying the pH level and subsequently performing heat treatment, which has a direct effect on morphology, crystallinity, and formation of different CaP powders.

Theoretical and experimental characterization of Pr/Ce co-doped hydroxyapatites

This study presents a more extensive report on the experimental and theoretical characterization of the Ce-doped hydroxyapatite (HAp) samples additionally doped with Pr at varying amounts. To achieve this goal, four Ce-containing (a constant amount of 0.35 at.%) HAps additionally doped with Pr at various amounts (0.35, 0.70, 1.05, and 1.40 at.%) were synthesized via a combustion method. Besides, all these samples were modeled theoretically by using a density functional theory (DFT). Theoretical results showed that the bandgap energy decreased continuously from 4.5156 to 4.3097 eV. For all samples, the linear attenuation (or absorption) coefficient increased with the increasing amount of Pr and this parameter had a decreasing trend with the increase in the photon energy. An increase in the theoretical density and the lattice parameter c and a decrease of both the lattice parameter a and the unit cell volume were found. After analyzing the experimental data, the following results were observed: X-ray diffraction (XRD) and Fourier transform infrared (FTIR) data verified the formation of HAp phase (above 94% for all the samples) as the major phase and beta-tricalcium phosphate (β-TCP) as the minor one. The amount of β-TCP phase was found to increase from 3.4 to 5.9% with the addition of Pr. Similar to the theoretical findings, an increasing trend for the density and decreasing one for the unit cell volume were detected. Both a decrease in the crystallinity and an increase in the anisotropic energy density were found. The results of the thermal analysis supported the thermal stability of all the samples. The cell viability was found to be affected by Pr-content.

Effect of MgO addition on the sinterability, mechanical properties and biological cell activities of sintered silicon-substituted hydroxyapatite

The effect of 1 wt% magnesium oxide (MgO) as sintering additive on the sintering behaviour, microstructure, mechanical properties and cell activities of 0.4 and 1.6 wt% silicon-substituted hydroxyapatite (MgO-0.4Si-HA and MgO-1.6Si-HA) was investigated. The powders were synthesized by the wet-chemical neutralization method and the compacts were pressureless sintered in air between 1150 and 1250 °C for 2 h. The results showed that MgO-0.4Si-HA promoted the formation of the secondary phase of β-TCP when sintered at 1250 °C, whilst the stability of the hydroxyapatite phase was not disrupted for the MgO-1.6Si-HA. The presence of MgO was found to be beneficial in suppressing grain growth of Si-HA when sintered at 1250 °C; however, it did not promote densification at lower temperatures (1150 and 1200 °C). It was observed that despite the lower densification, Vickers hardness and compressive strength of the MgO-Si-HA were higher than those of the undoped Si-HA samples. The beneficial effect of MgO in enhancing the biocompatibility of Si-HA has been revealed. It was found that the MgO-doped samples dramatically enhanced the osteogenic differentiation of MC3T3-E1 cells as shown from the higher cell proliferation, alkaline phosphatase activity and bone-like nodule formation when compared to pristine HA.

Gas pressure and coating distance for nanohydroxyapatite deposition on stainless steel 316L using flame spray technique

Metal implant coating engineering is needed to improve the surface biocompatibility properties of metals. For this, coating metal surfaces with bioactive and biocompatible biomaterials will be an option. Having high biocompatibility as well as similarity in chemical properties, nanohydroxyapatite may be a candidate as biomaterials for coating the metal implant. The key to the success of metal implant plating is the formation of pores which increase the bioactivity and biocompatibility properties of the implant. In this study, nanohydroxyapatite was used to be coated on stainless steel type 316L (SS316L). To ensure that the coating works properly on the surface, an appropriate measure of gas and distance is required. The purpose of this study was to determine the possible firing distance and gas pressure of the flame spray coating technique. The X-ray diffractometer (XRD), scanning electron microscope - energy dispersive X-ray spectroscopy (SEM-EDS), and optical microscopy (OM) characterizations were carried out to determine the phase, morphology, and presence of pores. After coated product, hydroxyapatite dehydroxylation occurred which led to the tetracalcium phosphate (TTCP) and β-tricalcium phosphate (β-TCP) phases. The thickness decreases with the addition of gas pressure and the farther the firing distance the layer thickness decreases. Nanohydroxyapatite coating on a bone implant substrate can increase the porosity of the layer.

Phase analysis, mechanical properties and in vitro bioactivity of graphene nanoplatelet-reinforced silicon nitride-calcium phosphate composites

ABSTRACT The aim of this study is to produce highly dense Si3N4 based composites with good mechanical properties and bioactivity. Si3N4 ceramics without using sintering aids, Si3N4-HA and Si3N4-HA-GNP based composites have been produced by spark plasma sintering (SPS) at temperatures of 1525–1550°C. The effect of reinforcement type and content on the densification behavior, phase analysis, microstructural development, mechanical properties, and in-vitro bioactivity behavior of Si3N4 were systematically investigated. Monolithic Si3N4 that contains a high amount of β-Si3N4 phase (~87 wt%) was produced by nearly full densification (~99%). Hydroxyapatite (HA) was used as a starting powder during the preparation of binary and triple composites to provide bioactivity to Si3N4, and after sintering, HA transformed into tricalcium phosphate (β-TCP and α-TCP) polymorphs. The incorporation of GNPs had a positive effect on the stability of β-TCP phases at higher sintering temperatures. The improvement in indentation fracture toughness of the samples with GNP reinforcement was mainly attributable to pull-out and crack deflection mechanisms. In-vitro bioactivity of GNP added composites enhanced with increasing α-TCP content. More calcium phosphate-based particle formation was observed in Si3N4-HA-GNP composites compared to the Si3N4-HA.

Biomechanical Evaluation of an Injectable Alginate / Dicalcium Phosphate Cement Composites for Bone Tissue Engineering

Biocompatible dicalcium phosphate (DCP) cements are widely used as bone repair materials. In this study, we aimed to investigate the impact of different amounts of sodium alginate (SA) on the microstructural, mechanical, and biological properties of DCP cements. Beta-tricalcium phosphate (β-TCP) was prepared using a microwave-assisted wet precipitation system. Lattice parameters of the obtained particles determined from X-ray diffraction (XRD), were in good match with a standard phase of β-TCP. Scanning electron microscopy (SEM) examination revealed that the particles were in globular shape. Furthermore, all functional groups of β-TCP were also detected using Fourier-transform infrared spectroscopy (FTIR) spectra. DCP cement (pure phase) was synthesized using monocalcium phosphate monohydrate (MCPM)/β-TCP powder mixture blended with 1.0 mL of water. SA/DCP cement composites were synthesized by dissolving different amounts of SA into water (1.0 mL) to obtain different final concentrations (0.5%, 1%, 2% and 3%). The prepared cements were characterized with XRD, SEM, FTIR and Thermogravimetric analysis (TGA). XRD results showed that pure DCP and SA/DCP cements were in a good match with Monetite phase. SEM results confirmed that addition of SA inhibited the growth of DCP particles. Setting time and injectability behaviour were significantly improved upon increasing the SA amount into DCP cements. In vitro biodegradation was evaluated using Simulated body fluid (SBF) over 21 days at 37 °C. The highest cumulative weight loss (%) in SBF was observed for 2.0% SA/DCP (about 26.52%) after 21 days of incubation. Amount of Ca2+ ions released in SBF increased with the addition of SA. DCP and SA/DCP cements showed the highest mechanical strength after 3 days of incubation in SBF and declined with prolonged immersion periods. In vitro cell culture experiments were conducted using Dental pulp stem cells (DPSCs). Viability and morphology of cells incubated in extract media of DCP and SA/DCP discs after 24 h incubation was studied with MTT assay and fluorescence microscopy imaging, respectively. All cements were cytocompatible and viability of cells incubated in extracts of cements was higher than observed in the control group. Based on the outcomes, SA/DCP bone cements have a promising future to be utilized as bone filler.

Structural and osteoblast cell response of strontium-zinc co-substituted nano-biphasic fluorohydroxyapatite

Strontium(Sr2+) and zinc(Zn2+) co-substituted nanobiphasic fluorohydroxyapatite (Ca10-x-ySrxZny(PO4)6F0.5OH1.5), [x = 5–40 mol% of Sr2+ and y = 5–20 mol% of Zn2+] improved osteoblastic cell response and is investigated in the present study. The structure, phase, thermal studies, morphology and composition were analysed by XRD, TG/DTA/DSC, FESEM and EDAX. The osteoblast cell response was analysed using MG-63 human osteosarcoma cells. The XRD pattern confirmed the presence of the β-TCP phase in nano-Sr/Zn-FHA which induces dissolution of Sr2+, Zn2+ and Ca2+ ions. The β-phase has influence on the osteoblasts for steady and sustained bone formation. The samples 40Sr/10Zn-FHA and 40Sr/5Zn-FHA exhibited sustained cell viability and alkaline phosphatase activity.

Pumice and perlite co-substituted hydroxyapatite: fabrication and characterization

The purpose of this study was to combine hydroxyapatite (HA) with pumice and perlite. A precipitation procedure was applied for synthesizing pure and doped hydroxyapatite. Samples were sintered at 1100°C for 1 h. These doped structures are characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM-EDS) and X-ray Fluorescence. Higher SiO2 and Al2O3 content was shown by XRF analysis. The XRD results revealed the existence of the HA, β-TCP and Ca5(PO4)2SiO4 phases. SEM images confirmed the sintering temperature and number of dopants had significant effect on grain sizes of the samples.

Tricalcium phosphate sheets with chitosan obtained via aqueous tape casting

Abstract Tricalcium phosphate (TCP) is a biomaterial produced in several biomedical applications, in addition to having biocompatibility and osteoconductive capacity. Biodegradable polymers of natural or synthetic origin such as chitosan and polyvinyl alcohol (PVA) have been used for tissue engineering applications because they have the properties of the native organic phase of bone tissue. Thus, the objective of this study was to obtain ceramic tapes based on TCP, chitosan, and PVA through the tape casting method. The viscosity data for all suspensions were ideal for the chosen processing. The thermogravimetric curves showed similar profiles, and it was possible to observe that a greater total mass loss occurred with the increase in the chitosan content. XRD reflections related to the β-TCP phase of the orthorhombic structure were found, showing no phase transformation. SEM analysis showed degrees of roughness on the film surfaces with little influence from the increase in chitosan content.

Piezoelectricity in Sr doped thick films of hydroxyapatite

The current study reports the synthesis, characterization and tape casting of strontium substituted into the calcium sublattice of hydroxyapatite in range of (0–100 mol%). The XRD powder data reveals that a primary HAp phase as well as secondary Ca 3 (PO 4 ) 2 (β-TCP) phase coexist. Our analysis shows that Sr+2 preferentially occupies the HAp lattice sites rather than β-TCP. Developed free-standing tapes of HAp offer unique possibility of custom designed solutions for biomedical applications by controlling shape size and tuned electrical properties. We report piezoelectricity in Sr doped hydroxyapatites thick films, the piezoelectric coefficient is an order of magnitude higher than what has been previously obtained in PLD deposited hydroxyapatite films [15]. The piezoelectricity shows slight improvement with the Sr doping. Despite low piezoelectric coefficient, the generated voltage is of the order of mV which is high enough to have physiological relevance since the resting potential of the cells lie between 60–90 mV. Further improvements in the material design and poling could pave way to understand the role of electricity in bone growth and to use piezoelectric energy harvesting to tune spinal and neuro stimulators.

Fabrication and properties of βTCP/Zeolite/Gelatin scaffold as developed scaffold in bone regeneration: in vitro and in vivo studies

Synthetic scaffolds, as an alternative to allograft and xenograft scaffolds, are suitable for bone regeneration. This study aimed to synthesize a composite biomaterial of zeolite and beta-tricalcium phosphate (βTCP) to obtain a biocompatible material with physical and mechanical properties in bone regeneration. One scaffold without zeolite (βZG 0) and two scaffolds with different amounts of zeolite (βZG 1 and βZG 2) were synthesized. The scaffolds were evaluated by FTIR, XRD, compressive strength test, MTT assay, and radiographic and histological analyses. The XRD results confirmed the presence of βTCP and ZSM-5 phases in the composite scaffolds and also, indicated that the addition of gelatin decrease the crystallinity of composite scaffolds. FTIR revealed the gelatin, β-TCP and ZSM-5 functional groups in the composite structure. βZG 2 group had the maximum porosity among the scaffolds (74%) ranging in size from 61-600 µm. Compressive strength test showed that the Young’s modulus changed from 23 MPa to 59 MPa, and the zeolite nanostructure was the most influential factor responsible for this change. The MTT assay showed the superiority of βZG 2, and the macroscopic and microscopic results at 4, 8, and 12 weeks revealed the maximum bone regeneration and formation of bone trabeculae in the βZG 2 and βZG 1 groups, respectively. The zeolite scaffold showed the superior mechanical, radiographic and histological properties compared with the control and non-zeolite scaffold. βTCP/ Zeolite/ Gelatin scaffold can be an appropriate candidate for medical application in bone regeneration.