Biphasic Calcium Phosphate Composites Research Articles

Biosynthesised Silver Nanoparticles Loading onto Biphasic Calcium Phosphate for Antibacterial and Bone Tissue Engineering Applications.

Biphasic calcium phosphate (BCP) serves as one of the substitutes for bone as it consists of an intimate mixture of beta-tricalcium phosphate (β-TCP) and hydroxyapatite (HAP) in different ratios. BCP, because of its inbuilt properties such as osteoconductivity, biocompatibility, and biostability in several clinical models serves as a bone substituent for orthopedic applications. Therefore, the present study aimed to assess the effectiveness of silver (Ag) nanoparticles (NPs) combined with BCP composites for the orthopedic sector of bone tissue regeneration and growth. In this regard, we first synthesized Ag-BCP microclusters by the double-emulsion method and then characterized the composite for various physicochemical properties, including the crystallinity and crystal structure, bonding and functionality, porosity, morphology, surface charges, topography, and thermal stability. In addition, the antibacterial activity of Ag-BCP was tested against gram-positive and gram-negative microorganisms such as Staphylococcus aureus, Candida albicans, and Escherichia coli. Finally, the cytocompatibility of Ag-BCP was confirmed against the fibroblast cells in vitro.

Dual-mode green emission and temperature sensing properties of rare-earth-element-doped biphasic calcium phosphate composites

This work presents a novel multifunctional material synthesized by hydroxyapatite/ β-tricalcium phosphate (HA/β-TCP) doped with Er-Yb-Mo ions (using hydrothermal method) and its characterization, showing a peculiar property of green dual-mode emissions (up and down-conversions). It was found that the obtained material exhibits an intense green emission (510–560 nm) both via up-conversion (excited by 975 nm) and down-conversion (excited by 379 nm), which depend on the Mo6+ contents. Particularly, compared with the free-Mo6+ sample, the green emission intensities of the samples doped with 5% Mo6+ mol are 50 and 35 times higher for UC and DC emissions, respectively. Furthermore, the temperature sensing property of the HA/β-TCP: Er-Yb-Mo composite is investigated by fluorescence intensity ratio (FIR) technique, showing a high and competitive sensitivity with a maximum value of 0.0064 K−1 at 403 K. The results indicated that the HA/β-TCP: Er-Yb-Mo phosphor can be useful for high-temperature-sensing applications.

Integrated 3D Information for Custom-Made Bone Grafts: Focus on Biphasic Calcium Phosphate Bone Substitute Biomaterials.

Purpose: Several studies showed that the sintering temperature of 1250 °C could affect the formation of α-Ca3(PO4)2, which is responsible for the reduction of the hardness value of biphasic calcium phosphate biocomposites, but they did not evaluate the inference of the sintering time at peak temperature on transition of β-Ca3(PO4)2 to α-Ca3(PO4)2. This analysis explored, in an innovative way, inferences and correlations between volumetric microstructure, mechanical properties, sintering temperature, and time at peak temperature in order to find the best sintering conditions for biphasic calcium phosphate composites grafted in severe alveolar bone defects. Methods: Sintered biphasic calcium phosphates (30%-hydroxyapatite/70%-tricalcium phosphate) were tested by microCT imaging for the 3D morphometric analysis, by compressive loading to find their mechanical parameters, and by X-ray diffraction to quantify the phases via Rietveld refinement for different sintering temperatures and times at the peak temperature. Data were analysed in terms of statistical inference using Pearson’s correlation coefficients. Results: All the studied scaffolds closely mimicked the alveolar organization of the jawbone, independently on the sintering temperatures and times; however, mechanical testing revealed that the group with peak temperature, which lasted for 2 hours at 1250 °C, showed the highest strength both at the ultimate point and at fracture point. Conclusion: The good mechanical performances of the group with peak temperature, which lasted for 2 hours at 1250 °C, is most likely due to the absence of the α-Ca3(PO4)2 phase, as revealed by X-ray diffraction. However, we detected its presence after sintering at the same peak temperature for longer times, showing the time-dependence, combined with the temperature-dependence, of the β-Ca3(PO4)2 to α-Ca3(PO4)2 transition.

Fabrication of graphene incorporated biphasic calcium phosphate composite and evaluation of impact of graphene in the in-vitro biomineralization process

The objective of this work is to design and development of graphene based bioceramic composite. The composition of graphene bioceramic composite is Hydroxyapatite/β-Tricalcium phosphate reinforced Graphene oxide (HAp/β-TCP/GO). The crystalline structure, chemical composition, morphology and elemental analysis of the developed composite were characterized using analytical techniques such as X-Ray Diffraction (XRD), Fourier Transform Infra red (FTIR) Spectroscopy, Raman Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS). In order to investigate the effect of graphene oxide on the in-vitro bio mineralization, the developed composite was immersed in Simulated Body Fluid (SBF) solution for various time periods (0, 7, 14 and 21 days) and the results indicate that the reinforcement of graphene oxide promotes the growth of hydroxyl apatite layer on the surface of composite discs. Further the developed composite of β-TCP/HAp reinforced graphene oxide can be used as a potential candidate material for biomedical applications.

Bone regenerative efficacy of biphasic calcium phosphate collagen composite as a carrier of rhBMP‐2

This study compared the bone regenerative effects of a recombinant human bone morphogenetic protein 2 (rhBMP-2)-loaded collagen-based biphasic calcium phosphate composite (BCPC) and rhBMP-2-loaded biphasic calcium phosphate (BCP). The in vitro release profiles of rhBMP-2-loaded BCP and BCPC were measured. The animal surgery was performed on ten rabbits. Four 8-mm-diameter circular calvarial defects were made and filled with BCP, BCPC, rhBMP-2-loaded BCP (BMP+BCP) and rhBMP-2-loaded BCPC (BMP+BCPC). The animals were euthanized either 2 or 8weeks after surgery. The initial burst release of rhBMP-2 was greater for BCP than for BCPC, and both presented a slow release pattern thereafter. In rabbit calvarial defects, the space maintaining capability and graft resorption of all experimental groups did not show statistical differences at 2 and 8weeks. New bone formation in the rhBMP-2-loaded groups was greater than in the non-loaded groups at both weeks, but the amount of new bone was comparable between both rhBMP-2-loaded groups at both weeks. There was a distinct histologic difference between the BMP+BCP and BMP+BCPC groups at 2weeks; the new bone formation occurred more in the intergranular spaces and the BCP-to-bone contact was greater in the BMP+BCPC group, but these differences were no longer discernible at 8weeks. BCP- and BCPC-loaded rhBMP-2 significantly improved bone regeneration and BCPC led to a dense network of new bone and bone particles during the early healing period. BCPC can therefore be considered as a promising candidate for carrying rhBMP-2.

Poly(trimethylene carbonate) and biphasic calcium phosphate composites for orbital floor reconstruction: a feasibility study in sheep

In the treatment of orbital floor fractures, bone is ideally regenerated. The materials currently used for orbital floor reconstruction do not lead to the regeneration of bone. Our objective was to render polymeric materials based on poly(trimethylene carbonate) (PTMC) osteoinductive, and to evaluate their suitability for use in orbital floor reconstruction. For this purpose, osteoinductive biphasic calcium phosphate (BCP) particles were introduced into a polymeric PTMC matrix. Composite sheets containing 50 wt% BCP particles were prepared. Also laminates with poly(D,L-lactide) (PDLLA) were prepared by compression moulding PDLLA films onto the composite sheets. After sterilisation by gamma irradiation, the sheets were used to reconstruct surgically-created orbital floor defects in sheep. The bone inducing potential of the different implants was assessed upon intramuscular implantation. The performance of the implants in orbital floor reconstruction was assessed by cone beam computed tomography (CBCT). Histological evaluation revealed that in the orbital and intramuscular implantations of BCP containing specimens, bone formation could be seen after 3 and 9 months. Analysis of the CBCT scans showed that the composite PTMC sheets and the laminated composite sheets performed well in orbital floor reconstruction. It is concluded that PTMC/BCP composites and PTMC/BCP composites laminated with PDLLA have osteoinductive properties and seem suitable for use in orbital floor reconstruction.

Microstructure and anisotropic mechanical properties of graphene nanoplatelet toughened biphasic calcium phosphate composite

Abstract Graphene nanoplatelets (GNPs) reinforced biphasic calcium phosphate (BCP) composites were prepared by hot pressing (HP). Based on in-depth mechanical test and observation of microstructure, the influence of GNPs on BCP matrix was investigated. A preferred orientation of GNPs occurred during sintering, leading to anisotropic mechanical properties. The mechanical properties of GNPs/BCP composite measured along the direction parallel to the HP direction are higher than those measured along the perpendicular direction. Parallel to the HP direction, the composite containing 1.5 wt% GNPs exhibited the maximun bending strength and fracture toughness of 151.82 MPa and 1.74 MPa m 1/2 , about 55% and 76% higher than those of monolithic BCP, respectively. The improvement in mechanical properties was mainly attributable to crack deflection, crack branching, bridging, pullout and fracture of GNPs. Especially GNPs can force crack to propagate not only in two but also in three dimensions.

Electrically Polarized Biphasic Calcium Phosphates: Adsorption and Release of Bovine Serum Albumin

In this study, we applied electrical polarization technique to increase adsorption and control protein release from biphasic calcium phosphate (BCP). Three different biphasic calcium phosphate (BCP) composites, with hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP), were processed and electrically polarized. Our study showed that stored charge was increased in the composites with the increase in HAp percentage. Adsorption of bovine serum albumin (BSA), as a model protein, on the poled as well as unpoled surfaces of the composites was studied. The highest amount of BSA adsorption was obtained on positively poled surfaces of each composite. Adsorption isotherm study suggested a multilayer adsorption of BSA on the BCP composites. The effect of electrical polarization on BSA release kinetics from positively charged BCP surfaces was studied. A gradual increase in percent BSA release from positively charged BCP surfaces with decreasing stored charge was observed. Our study showed that the BCP based composites have the potential to be used as a drug or growth factor delivery vehicle.

Mesenchymal cell response to nanosized biphasic calcium phosphate composites

Biphasic calcium phosphate nanoparticles comprising both hydroxyapatite (HA) and β polymorph of tricalcium phosphate (β-TCP) have been synthesized together by a polymer matrix mediated process. The process, based on in situ mineralization of poly (vinyl alcohol), exerts a good control over the morphological features of biphasic nanoparticles. By controlling the reaction chemistry (Ca:P ratios), nanobioceramic particles having three different HA/β-TCP ratios of 50:50, 55:45 and 60:40 respectively. As the two constituents of biphasic system (HA and β-TCP) facilitate series of signaling cascades in osteoblast division and differentiation, the adhesion and differentiation properties of mesenchymal cells (MSCs) derived from bone marrow has been studied.

Biological performance in goats of a porous titanium alloy–biphasic calcium phosphate composite

In this study, porous 3D fiber deposition titanium (3DFT) and 3DFT combined with porous biphasic calcium phosphate ceramic (3DFT+BCP) implants, both bare and 1 week cultured with autologous bone marrow stromal cells (BMSCs), were implanted intramuscularly and orthotopically in 10 goats. To assess the dynamics of bone formation over time, fluorochrome markers were administered at 3, 6 and 9 weeks and the animals were sacrificed at 12 weeks after implantation. New bone in the implants was investigated by histology and histomorphometry of non-decalcified sections. Intramuscularly, no bone formation was found in any of the 3DFT implants, while a very limited amount of bone was observed in 2 BMSC 3DFT implants. 3DFT+BCP and BMSC 3DFT+BCP implants showed ectopic bone formation, in 8 and 10 animals, respectively. The amount of formed bone was significantly higher in BMSC 3DFT+BCP as compared to 3DFT+BCP implants. Implantation on transverse processes resulted in significantly more bone formation in composite structure as compared to titanium alloy alone, both with and without cells. Unlike intramuscularly, the presence of BMSC did not have a significant effect on the amount of new bone either in metallic or in composite structure. Although the 3DFT is inferior to BCP for bone growth, the reinforcement of the brittle BCP with a 3DFT cage did not negatively influence osteogenesis, osteoinduction and osteoconduction as previously shown for the BCP alone. The positive effect of BMSCs was observed ectopically, while it was not significant orthotopically.

Preparation and Characterization of the Microspheres Comprised of Atelocollagen and BCP

In order to develop a bone-filling material with osteoinductive potential, a composite micorspheres of collagen molecules and biphasic calcium phosphate (BCP) was prepared by utilizing emulsion polymerization and the intrinsic self-assembly of collagen. The prepared microspheres were analyzed by granularity test, scanning electron microscopy (SEM), infrared spectra (IR) and enzymatic digestion experiment. The results showed that the collagen matrix of fibrils was reconstituted in the droplets, and the native triple-helix structure of collagen was still maintained. The study provides an effective way to prepare microspheres of collagen and BCP composite.