Improvement of anti-washout property of calcium phosphate cement by addition of konjac glucomannan and guar gum.

The inferior anti-washout property of injectable calcium phosphate cement (CPC) limits its wider application in clinic. In this study, the improvement of anti-washout performance of CPC by addition of konjac glucomannan or guar gum, which was dissolved in the CPC liquid, was first studied. The influence of KGM/GG blend with different mass ratios on the anti-washout property, compressive strength and in vitro cytocompatibility of CPC was estimated. The results revealed that small amount of KGM or GG could obviously enhance the anti-washout property of CPC. Moreover, the washout resistance efficiency of KGM/GG blend was better than KGM or GG alone. The addition of KGM/GG blend slightly shortened the final setting time of CPC. Although the introduction of KGM/GG blend reduced the compressive strength of CPC, the compressive strength still reached or surpassed that of human cancellous bone. The best KGM/GG mass ratio was 5:5, which was most efficient at not only reducing CPC disintegration, but also increasing compressive strength. The addition of KGM/GG blend obviously promoted the cells proliferation on the CPC. In short, the CPC modified by KGM/GG blend exhibited excellent anti-washout property, appropriate setting time, adequate compressive strength, and good cytocompatibility, and has the potential to be used in bone defect repair. The addition of KGM/GG blend significantly improved the anti-washout property of CPC. The best KGM/GG mass ratio was 5:5, which was most efficient in reducing the CPC disintegration.

In vivo immunotoxicity of SiO2@(Y0.5Gd0.45Eu0.05)2O3 as dual-modality nanoprobes.

We have successfully synthesized SiO2@(Y0.5Gd0.45Eu0.05)2O3 nanocomposites as a potential dual-modality nanoprobe for molecular imaging in vitro. However, their immunotoxicity assessment in vivo remains unknown. In this article, the in vitro biocompatibility of our dual-modality nanoprobes was assayed in terms of cell viability and apoptosis. In vivo immunotoxicity was investigated by monitoring the generation of reactive oxygen species (ROS), cluster of differentiation (CD) markers and cytokines in Balb/c mice. The data show that the in vitro biocompatibility was satisfactory. In addition, the immunotoxicity data revealed there are no significant changes in the expression levels of CD11b and CD71 between the nanoprobe group and the Gd in a diethylenetriaminepentaacetic acid (DTPA) chelator (Gd-DTPA) group 24 h after injection in Balb/c mice (p>0.05). Importantly, there are significant differences in the expression levels of CD206 and CD25 as well as the secretion of IL-4 and the generation of ROS 24 h after injection (p<0.05). Transmission electron microscopy (TEM) images showed that few nanoprobes were localized in the phagosomes of liver and lung. In conclusion, the toxic effects of our nanoprobes may mainly result from the aggregation of particles in phagosomes. This accumulation may damage the microstructure of the cells and generate oxidative stress reactions that further stimulate the immune response. Therefore, it is important to evaluate the in vivo immunotoxicity of these rare earth-based biomaterials at the molecular level before molecular imaging in vivo.

Fabrication of 3D printed Ca3Mg3(PO4)4-based bioceramic scaffolds with tailorable high mechanical strength and osteostimulation effect.

Calcium, magnesium and phosphate are predominant constituents in the human bone. In this study, magnesium-calcium phosphate composite bioceramic scaffolds were fabricated utilizing Mg3(PO4)2 and ß-Ca3(PO4)2 as starting materials, and their pore structure was constructed by 3D printing. The porosity and compressive strength of the composite bioceramic scaffolds could be adjusted by altering the sintering temperature and the formula of starting materials. The composite bioceramic scaffolds prepared from 60 wt% Mg3(PO4)2 and 40 wt% ß-Ca3(PO4)2 were dominated by the Ca3Mg3(PO4)4 phase, and this Ca3Mg3(PO4)4-based bioceramic scaffolds possessed the highest compressive strength (12.7 - 92.4 MPa). Moreover, the Ca3Mg3(PO4)4-based bioceramic scaffolds stimulated cellular growth and osteoblastic differentiation of bone marrow stromal cells. The Ca3Mg3(PO4)4-based bioceramic scaffolds as bone regenerative biomaterials are flexible to the requirement of bone defects at various sites.

Fabrication of strontium carbonate-based composite bioceramics as potential bone regenerative biomaterials.

Strontium carbonate (SrC) bioceramics are proposed as potential biomaterials to efficaciously repair the bone defects. However, the development of SrC bioceramics is restricted by their intrinsic low mechanical strength. In this study, SrC-based composite bioceramics (SrC-SrP) were fabricated by incorporating strontium-containing phosphate glass (SrP). The results indicated that aside from the main crystalline phase SrC, new compounds were generated in the SrC-SrP bioceramics. Incorporating 10 wt% SrP promoted densification, thus dramatically improving compressive strength of SrC-SrP bioceramics. The SrC-SrP bioceramics facilitated apatite precipitation on their surface, and sustainedly released strontium, phosphorus and sodium ions. Compared with the well-known ß-tricalcium phosphate bioceramics, the SrC-SrP bioceramics with certain amounts of SrP enhanced proliferation, alkaline phosphatase activity and osteogenesis-related gene expressions of mouse bone mesenchymal stem cells. The SrC-SrP bioceramics with appropriate constituent can serve as novel bone regenerative biomaterials.

Zinc-doped calcium silicate additive accelerates early angiogenesis and bone regeneration of calcium phosphate cement by double bioactive ions stimulation and immunoregulation.

Calcium phosphate cement (CPC), a popular injectable bone defect repairing material, has deficiencies in stimulating osteogenesis and angiogenesis. To overcome the weaknesses of CPC, zinc-doped calcium silicate (Zn-CS) which can release bioactive silicon (Si) and zinc (Zn) ions was introduced to CPC. The physicochemical and biological properties of CPC and its composites were evaluated. Firstly, the most effective addition content of calcium silicate (CaSiO3, CS) in promoting the in vitro osteogenesis was first sorted out. On this basis, the most effective Zn doping content in CS for improving osteogenic differentiation of CPC-based composites was screened out. Finally, the immunoregulation of CS/CPC and Zn-CS/CPC in promoting angiogenesis and osteogenesis was studied. The results showed that the most effective incorporation content of CS was 10 wt%. Zn at a doping content of 30 mol% in CS (30Zn-CS) further enhanced the osteogenic capacity of CS/CPC and simultaneously maintained excellent proangiogenic activity. CS/CPC and 30Zn-CS/CPC promoted the recruitment of macrophages and enhanced M2 polarization while inhibiting M1 polarization, which was beneficial to the early vascularization as well as subsequent new bone formation. When implanted into the femoral condylar defects of rabbits, 30Zn-CS/CPC showed high in vivo materials degradation rate, angiogenesis and osteogenesis, due to the synergistic effects of Si and Zn on bio-stimulation and immunoregulation. This study shed light on the synergistic effects of Si and Zn on regulating the angiogenic, osteogenic, and immunoregulatory activity, and 30Zn-CS/CPC is expected to repair the lacunar bone defects effectively.

Enhanced osteogenesis of honeycomb ß-tricalcium phosphate scaffold by construction of interconnected pore structure: An in vivo study.

Pore structure plays an important role in the in vivo osteogenesis for bone repair materials. In this study, honeycomb ß-tricalcium phosphate (ß-TCP) scaffolds were prepared by extrusion method, and gelatin microspheres were used as porogens to modify the pore structure of the scaffolds. The honeycomb ß-TCP scaffolds were characterized by channel-like square macropores and unidirectional interconnection. To improve the pore interconnectivity of the scaffold, the spherical pores were formed in the channel walls by burning off the gelatin microspheres. Compared with unidirectional honeycomb ß-TCP scaffold, the honeycomb ß-TCP scaffold with interconnected pore structure had significantly higher porosity and faster degradation rate, at the expense of the mechanical strength. The in vivo assessment results demonstrated excellent osteogenesis of the honeycomb scaffolds. Moreover, the honeycomb ß-TCP scaffold with interconnected pore structure markedly promoted new bone formation in comparison with the unidirectional honeycomb ß-TCP scaffold. This work provides a new approach to prepare scaffolds with interconnected pore structure, and the honeycomb ß-TCP scaffold with interconnected pore structure is expected to serve as an efficient bone repair material.

Effects of strontium amount on the mechanical strength and cell-biological performance of magnesium-strontium phosphate bioceramics for bone regeneration.

Magnesium and strontium are able to enhance osteogenesis and suppress osteoclastic activities simultaneously, and they were nontoxic in wide concentration ranges; these make the magnesium-strontium phosphate bioceramics suitable for treating osteoporotic bone defects. The aim of this study was to investigate the effects of strontium amount on the mechanical strength and cell-biological performance of magnesium-strontium phosphate [MgxSr3-x(PO4)2; 3-x = 0, 0.1, 0.25, 0.5, 0.75, 1] bioceramics, which were sintered at 1100 °C. The results indicated that the magnesium-strontium phosphate bioceramics except Mg2.9Sr0.1(PO4)2 and Mg2.25Sr0.75(PO4)2 bioceramics had considerable compressive strength. The variation in magnesium and strontium contents did not regularly affect the in vitro osteogenic differentiation and osteoclastic activities. The Mg2.75Sr0.25(PO4)2 bioceramic had the most desirable overall performance, as reflected by considerably high compressive strength, enhanced in vitro osteogenesis and inhibited osteoclastic activities. Therefore, the Mg2.75Sr0.25(PO4)2 bioceramic is considered a promising biomaterial for osteoporotic bone regeneration.

Novel Extrusion-Microdrilling Approach to Fabricate Calcium Phosphate-Based Bioceramic Scaffolds Enabling Fast Bone Regeneration.

This study proposes a novel approach, termed extrusion-microdrilling, to fabricate three-dimensional (3D) interconnected bioceramic scaffolds with channel-like macropores for bone regeneration. The extrusion-microdrilling method is characterized by ease of use, high efficiency, structural flexibility, and precision. The 3D interconnected ß-tricalcium phosphate bioceramic (EM-TCP) scaffolds prepared by this method showed channel-like square macropores (∼650 µm) by extrusion and channel-like round macropores (∼570 µm) by microdrilling as well as copious micropores. By incorporating a strontium-containing phosphate-based glass (SrPG), the obtained calcium phosphate-based bioceramic (EM-TCP/SrPG) scaffolds had noticeably higher compressive strength, lower porosity, and smaller macropore size, tremendously enhanced in vitro proliferation and osteogenic differentiation of mouse bone marrow stromal cells, and suppressed in vitro osteoclastic activities of RAW264.7 cells, as compared with the EM-TCP scaffolds. In vivo assessment results indicated that at postoperative week 6, new vessels and a large percentage of new bone tissues (24-25%) were formed throughout the interconnected macropores of EM-TCP and EM-TCP/SrPG, which were implanted in the femoral defects of rabbits; the bone formation of the EM-TCP group was comparable to that of the EM-TCP/SrPG group. At 12 weeks postimplantation, the bone formation percentage of EM-TCP was slightly reduced, while that of EM-TCP/SrPG with a slower degradation rate was pronouncedly increased. This work provides a new strategy to fabricate interconnected bioceramic scaffolds allowing for fast bone regeneration, and the EM-TCP/SrPG scaffolds are promising for efficiently repairing bone defects.

Novel Strategy to Accelerate Bone Regeneration of Calcium Phosphate Cement by Incorporating 3D Plotted Poly(lactic-co-glycolic acid) Network and Bioactive Wollastonite.

Inefficient bone regeneration of self-hardening calcium phosphate cement (CPC) increases the demand for interconnected macropores and osteogenesis-stimulated substances. It remains a challenge to fabricate porous CPC with interconnected macropores while maintaining its advantages, such as plasticity. Herein, pastes containing CPC and wollastonite (WS) are infiltrated into a 3D plotted poly(lactic-co-glycolic acid) (PLGA) network to fabricate plastic CPC-based composite cement (PLGA/WS/CPC). The PLGA/WS/CPC recovers the plasticity of CPC after being heated above the glass transition temperature of PLGA. The presence of the 3D PLGA network significantly increases the flexibility of CPC in prophase and generates 3D interconnected macropores in situ upon its degradation. The addition of WS is helpful to improve the attachment, proliferation, and osteogenic differentiation of mouse bone marrow stromal cells in vitro. The in vivo experimental results indicate that PLGA/WS/CPC promotes rapid angiogenesis and bone formation. Therefore, the plastic CPC-based composite cement with a 3D PLGA network and wollastonite shows an obviously improved efficiency for repairing bone defects and is expected to facilitate the wider application of CPC in the clinic.

Improving osteogenesis of calcium phosphate bone cement by incorporating with lysine: An in vitro study.

Calcium phosphate bone cement (CPC) has attracted extensive interests from surgeons and material scientists. However, its actual application is still limited because of its poor osteogenesis. In this work, lysine, one of the essential components of proteins, was incorporated into the CPC to improve its osteogenesis ability. Effects of lysine on the phase, morphology, physicochemical properties, protein adsorption, lysine release and cytocompatibility of CPC were investigated. Results showed that lysine had no significant influence on the phase and morphology of the hydrated cements, but evidently raised the compressive strength, apparent porosity and setting time of the cements in a content-dependent manner of lysine. In contrast to the control, the lysine-incorporated CPCs had notably enhanced in vitro osteogenesis capability. It was supposed to be synergistically attributed to the improvements of fibronectin (FN) anchoring and bone mesenchymal stem cells (BMSCs) adhesion on the hydrated cements as well as the sustained release of bioactive amino acid molecules. Hence, lysine was expected to be applied as a novel bioactive admixture in the development of CPC with the improved osteogenesis ability and physicochemical properties for numerous orthopedic applications.

Improving the anti-washout property of calcium phosphate cement by introducing konjac glucomannan/κ-carrageenan blend.

Anti-washout calcium phosphate cement (CPC) was prepared by dissolving water-soluble konjac glucomannan (KGM) and κ-carrageenan (KC) blend in the cement liquid. The anti-washout property, setting time, compressive strength and in vitro cytocompatibility of the CPC modified with KGM/KC blend were evaluated. The results indicated that the CPC pastes modified with KGM/KC blend exhibited excellent anti-washout property. The addition of KGM/KC blend shortened the setting time and increased the injectability of CPC. Although the introduction of KGM/KC blend reduced the compressive strength of CPC, the compressive strength still surpassed that of human cancellous bone. The optimal KGM/KC mass ratio was 2:8, with which the modified cement exhibited the most efficient washout resistance and the highest compressive strength. The introduction of KGM/KC blend obviously promoted the proliferation of mouse bone marrow mesenchymal stem cells. This anti-washout CPC modified by KGM/KC blend with excellent in vitro cytocompatibility will have good prospects for application in bone defect repair.

Concentration-dependent osteogenic and angiogenic biological performances of calcium phosphate cement modified with copper ions.

Development of multifunctional bone grafting biomaterials with both osteogenesis and angiogenesis properties have earned increasing interest in the field of regenerative medicine. In the present investigation, copper-doped ß-tricalcium phosphate (Cu-TCP) powders were successfully synthesized. And Cu-containing calcium phosphate cement (Cu-CPC) was acquired through uniformly mixing CPC and Cu-TCP powders, with Cu-TCP serving as the donor of Cu2+. Cu-CPC exhibited suitable setting time, and the incorporation of Cu-TCP aggregating into CPC exhibited positive effect on the compressive strength while Cu2+ was in lower concentration. Investigation results showed that Cu-CPC had relatively low releasing amount of Cu2+, which was attributed to the re-bonding of Cu2+ into the newly formed HA crystals on surface. In vitro osteogenesis and angiogenesis properties of Cu-CPC were systematically evaluated through co-culture with mouse bone marrow stromal cells (mBMSCs) and human umbilical vein endothelial cells (HUVECs) respectively. The results indicated dose-dependent biological functions of Cu2+ in Cu-CPCs. The mBMSCs and HUVECs showed well activity and attachment morphology on TCP/CPC, 0.05 Cu-TCP/CPC, 0.1 Cu-TCP/CPC. The upregulated osteogenic-related genes expression and angiogenic-related genes expression were detected with lower Cu2+ content. Taken together, Cu-containing CPC is of great potential for the regeneration of vascularized new bone.

Strontium ranelate simultaneously improves the radiopacity and osteogenesis of calcium phosphate cement.

In a minimally invasive surgery of osteoporotic fractures, high radiopacity is necessary to monitor the delivery and positioning of injectable cements and good osteogenesis is indispensable. In this work, strontium ranelate (SrR), an agent for treating osteoporosis, is firstly used as a radiopaque agent for calcium phosphate cement (CPC). The addition of SrR does not affect the hydration products of CPC, but prolonged the setting time and decreased the compressive strength. The injectability of the cement was higher than 85% when SrR content is more than 10 wt%. The radiopacity of CPC is significantly improved by SrR and higher than cortical bone when the content of SrR is more than 5 wt%. The concentration of Sr ions released from CPC is increased by the increasing content of SrR, which is among 17-1329 µM. Moreover, CPCs with SrR significantly promote the osteogenic differentiation of mouse bone marrow mesenchymal stem cells and inhibit the osteoclastogenic differentiation of RAW264.7 cells. Based on its good radiopacity and osteogenesis, suppressed osteoclastogenesis and appropriate physicochemical properties, the radiopaque CPC with more than 10 wt% SrR is prospective to be a promising biomaterial for osteoporotic fracture repairing in minimal invasive surgery.

Study on MgxSr3-x(PO4)2 bioceramics as potential bone grafts.

Magnesium (Mg) and strontium (Sr), which are essential nutrient elements in the natural bone, positively affect the osteogenic activity even in wide ranges of ion concentrations. However, it remains unknown whether magnesium-strontium phosphates [MgxSr3-x(PO4)2] are potential bone grafts for accelerating bone regeneration. Herein, a serial of MgxSr3-x(PO4)2, including Mg3(PO4)2, Mg2Sr(PO4)2, Mg1.5Sr1.5(PO4)2, MgSr2(PO4)2 and Sr3(PO4)2, were synthesized using a solid-state reaction approach. The physicochemical properties and cell behaviors of MgxSr3-x(PO4)2 bioceramics were characterized and compared with the common bone graft ß-tricalcium phosphate (ß-TCP). The results indicated that various MgxSr3-x(PO4)2 bioceramics differed in compressive strength and in vitro degradation rate. All the MgxSr3-x(PO4)2 bioceramics had excellent biocompatibility. In contrast to ß-TCP, the MgxSr3-x(PO4)2 enhanced alkaline phosphatase activity of mouse bone mesenchymal stem cells (mBMSCs), and inhibited osteoclastogenesis-related gene expression of RAW264.7 cells, but did not enhance osteogenesis-related gene expression of mBMSCs which were treated with osteogenesis induction supplements. However, Mg3(PO4)2 stimulated osteogenesis-related gene expression of mBMSCs without the treatment of osteogenesis induction supplements. This work contributes to the design of bone graft and may open a new avenue for the bone regeneration field.

Hierarchically porous structure, mechanical strength and cell biological behaviors of calcium phosphate composite scaffolds prepared by combination of extrusion and porogen burnout technique and enhanced by gelatin.

In this study, hierarchically porous calcium phosphate scaffolds (HTCP) with unidirectional pores, transversely interconnected pores, and micropores were fabricated by the combination of extrusion and porogen burnout technique. Gelatin was incorporated into the HTCP scaffolds by vacuum-impregnation of gelatin solution and subsequent freeze-drying. The phase composition, microstructure, physical and cytobiological properties were analyzed. The results showed that the HTCP scaffolds were composed of ß-tricalcium phosphate with minor hydroxyapatite. The HTCP scaffolds had unidirectional pores (~400µm), transversely interconnected pores (~130µm) and micropores (~1µm). The incorporation of gelatin significantly increased the compressive strength, toughness, and cell seeding of the HTCP scaffolds. The composite scaffolds showed excellent cytocompatibility. The hierarchically porous calcium phosphate composite scaffolds may have potential application prospects in bone tissue engineering.

Tailoring the mechanical property and cell-biological response of ß-tricalcium phosphate composite bioceramics by SrO-P2O5-Na2O based additive.

ß-tricalcium phosphate (ß-TCP) bioceramic, which is a prevalent bone graft, is deficient in mechanical strength and mediating the biological functions. In the present study, ß-tricalcium phosphate composite bioceramics (TCP/SPNs) were prepared by introducing SrO-P2O5-Na2O based (SPN) sintering additive. With increasing mole ratio of SrO to P2O5, the SPN tended to crystallize. In the liquid-phase sintering process, ß-TCP reacted with SPN, producing new compounds. The difference in characteristic of SPN additive affected the compressive strength and cell-biological response of the fabricated TCP/SPNs. By selecting SPN with appropriate formulation, the TCP/SPNs not only could more than double their compressive strength, but also improved the cell viability, promoted osteogenic differentiation and inhibited osteoclastic activities. Taken together, this work establishes a beneficial strategy to improve the overall performance of calcium phosphate bioceramic for application in bone regeneration.

Enhancing the Bioactivity of Yttria-Stabilized Tetragonal Zirconia Ceramics via Grain-Boundary Activation.

Yttria-stabilized tetragonal zirconia (Y-TZP) has been proposed as a potential dental implant because of its good biocompatibility, excellent mechanical properties, and distinctive aesthetic effect. However, Y-TZP cannot form chemical bonds with bone tissue because of its biological inertness, which affects the reliability and long-term efficacy of Y-TZP implants. In this study, to improve the bioactivity of Y-TZP ceramics while maintaining their good mechanical performance, Y-TZP was modified by grain-boundary activation via the infiltration of a bioactive glass (BG) sol into the surface layers of Y-TZP ceramics under different negative pressures (atmospheric pressure, -0.05 kPa, and -0.1 kPa), followed by gelling and sintering. The in vitro bioactivity, mechanical properties, and cell behavior of the Y-TZP with improved bioactivity were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), electron probe microanalysis (EPMA), and Raman spectroscopy. The results of the bioactivity test conducted by immersing Y-TZP in simulated body fluid (SBF) showed that a bonelike apatite layer was produced on the entire surface. The mechanical properties of the modified Y-TZP decreased as the negative pressure in the BG-infiltration process increased relative to those of the Y-TZP blank group. However, the samples infiltrated with the BG sol under -0.05 kPa and atmospheric pressure still retained good mechanical performance. The cell-culture results revealed that the bioactive surface modification of Y-TZP could promote cell adhesion and differentiation. The present work demonstrates that the bioactivity of Y-TZP can be enhanced by grain-boundary activation, and the bioactive Y-TZP is expected to be a potential candidate for use as a dental implant material.

Fabrication of ß-tricalcium phosphate composite ceramic sphere-based scaffolds with hierarchical pore structure for bone regeneration.

Polymer sphere-based scaffolds, which are prepared by bonding the adjacent spheres via sintering the randomly packed spheres, feature uniform pore structure, full three-dimensional (3D) interconnection, and considerable mechanical strength. However, bioceramic sphere-based scaffolds fabricated by this method have never been reported. Due to high melting temperature of bioceramic, only limited diffusion rate can be achieved when sintering the bioceramic spheres, which is far from enough to form robust bonding between spheres. In the present study, for the first time we fabricated 3D interconnected ß-tricalcium phosphate ceramic sphere-based (PG/TCP) scaffolds by introducing phosphate-based glass (PG) as sintering additive and placing uniaxial pressure during the sintering process. The sintering mechanism of PG/TCP scaffolds was unveiled. The PG/TCP scaffolds had hierarchical pore structure, which was composed by interconnected macropores (>200 µm) among spheres, pores (20­120 µm) in the interior of spheres, and micropores (1­3 µm) among the grains. During the sintering process, partial PG reacted with ß-TCP, forming ß-Ca2P2O7; metal ions from PG substituted to Ca2+ sites of ß-TCP. The mechanical properties (compressive strength 2.8­10.6 MPa; compressive modulus 190­620 MPa) and porosity (30%­50%) of scaffolds could be tailored by manipulating the sintering temperatures. The introduction of PG accelerated in vitro degradation of scaffolds, and the PG/TCP scaffolds showed good cytocompatibility. This work may offer a new strategy to prepare bioceramic scaffolds with satisfactory physicochemical properties for application in bone regeneration.

Comparative study on in vivo response of porous calcium carbonate composite ceramic and biphasic calcium phosphate ceramic.

In a previous study, robust calcium carbonate composite ceramics (CC/PG) were prepared by using phosphate-based glass (PG) as an additive, which showed good cell response. In the present study the in vivo response of porous CC/PG was compared to that of porous biphasic calcium phosphate ceramics (BCP), using a rabbit femoral critical-size grafting model. The materials degradation and bone formation processes were evaluated by general observation, X-ray radiography, micro-computed tomography, and histological examination. The results demonstrated excellent biocompatibility and osteoconductivity, and progressive degradation of CC/PG and BCP. Although the in vitro degradation rate of CC/PG was distinctly faster than that of BCP, at 4week post-implantation, the bone generation and material degradation of CC/PG were less than those of BCP. Nevertheless, at postoperative week 8, the increment of bone formation and material degradation of CC/PG was pronouncedly larger than that of BCP. These results show that CC/PG is a potential resorbable bone graft aside from the traditional synthetic ones.

A facile magnesium-containing calcium carbonate biomaterial as potential bone graft.

The calcium carbonate is the main composition of coral which has been widely used as bone graft in clinic. Herein, we readily prepared novel magnesium-containing calcium carbonate biomaterials (MCCs) under the low-temperature conditions based on the dissolution-recrystallization reaction between unstable amorphous calcium carbonate (ACC) and metastable vaterite-type calcium carbonate with water involved. The content of magnesium in MCCs was tailored by adjusting the proportion of ACC starting material that was prepared using magnesium as stabilizer. The phase composition of MCCs with various amounts of magnesium was composed of one, two or three kinds of calcium carbonates (calcite, aragonite, and/or magnesian calcite). The different MCCs differed in topography. The in vitro degradation of MCCs accelerated with increasing amount of introduced magnesium. The MCCs with a certain amount of magnesium not only acquired higher compressive strength, but also promoted in vitro cell proliferation and osteogenic differentiation. Taken together, the facile MCCs shed light on their potential as bone graft.