Porous Calcium Phosphate Scaffolds Research Articles

Europium-Doped 3D Dimensional Porous Calcium Phosphate Scaffolds as a Strategy for Facilitating the Comprehensive Regeneration of Bone Tissue: In Vitro and In Vivo.

In response to the challenges faced by clinicians treating bone defects caused by various factors, various bone repair materials have been investigated, but the efficiency of bone healing still needs to be improved due to the acting of scaffolds only in a single stage of bone tissue regeneration. We investigated the potential of a novel 3D scaffold to support different stages of bone tissue regeneration, including initial inflammation, proliferation, and remodeling. Eu (0, 0.5, 2, 3.5, 5, and 6.5%) was added to calcium polyphosphate to obtain 3D porous network-doped Eu calcium polyphosphate (EuCPP) scaffolds with ideal mechanical strength and pore size. Both in vitro and in vivo experiments proved that Eu3+ released from 5% EuCPP scaffolds could significantly promote the migration and proliferation of bone marrow stromal cells which effectively promote angiogenesis; 5% EuCPP could significantly upregulate the ratio of OPG/RANKL in MC3T3-E1 and promote the secretion of osteogenic-related growth factors (ALP and OPN) from MC3T3-E1, indicating the potential of the scaffold to inhibit bone resorption and promote bone formation. In conclusion, 5% EuCPP possesses the biological properties of pro-angiogenesis, anti-inflammation, pro-osteogenesis, and inhibiting bone resorption, which may provide a sustained positive effect throughout the process of bone tissue repair.

Porous silica-doped calcium phosphate scaffolds prepared via in-situ foaming method

The effect of silica (SiO2) addition (0 wt%-20 wt%) on the microstructural and mechanical properties, as well as the in vitro response of calcium phosphate scaffolds for potential application in bone tissue engineering (BTE) was investigated in this research. Scaffolds characterized by high porosity (77%–88 %) and interconnected spherical pores with a broad range of pore sizes (5–600 μm) were fabricated using in-situ foaming method. Incorporated silica affected the phase transformation of hydroxyapatite (HA) to β-tricalcium phosphate (β-TCP) and led to the development of new crystalline silica-rich phases like silicocarnotite and wollastonite. The reinforcement of silica became apparent during the tests of mechanical properties. Scaffolds with 5 wt% of SiO2 exhibited compressive strength (1.13 MPa) higher than pure HA scaffolds (0.93 MPa). Bone bonding potential of the materials was tested in simulated body fluid (SBF), demonstrating this potential in silica-doped samples. Additionally, degradation experiments showed gradual material degradation, making it suitable for BTE applications. Furthermore, cell culture studies using human mesenchymal stromal cells (MSC) confirmed the scaffold's non-toxicity and provided insights into how the silica content influences cell viability, morphology, and osteogenic potential. The findings of this study offer valuable insights into the design and development of advanced scaffolds with tailored properties for effective BTE applications.

Osteogenic differentiation of adipose-derived canine mesenchymal stem cells seeded in porous calcium-phosphate scaffolds.

Engineered bone graft substitutes are a promising alternative and supplement to autologous bone grafts as treatments for bone healing impairment. Advances in human medicine extend an invitation to pursue these biomimetic strategies in animal patients, substantiated by the theory that specialized scaffolds, multipotent cells, and biological cues may be combined into a bioactive implant intended for the enhancement of tissue regeneration. This proof-of-concept study was designed to evaluate and validate the feasibility of beta-tricalcium phosphate foam scaffolds seeded with canine mesenchymal stem cells derived from adipose tissue. Cell-inoculated samples and sham controls were cultured statically for 72 hours in complete growth medium to evaluate seeding capacity, while a subset of loaded scaffolds was further induced with osteogenic culture medium for 21 days. Produced implants were characterized and validated with a combination of immunofluorescence and reflection confocal microscopy, scanning electron microscopy, and polymerase chain reaction to confirm osteogenic differentiation in tridimensional-induced samples. After 72 hours of culture, all inoculated scaffolds presented widespread yet heterogeneous surface seeding, distinctively congregating stem cells around pore openings. Furthermore, at 21 days of osteogenic culture conditions, robust osteoblastic differentiation of the seeded cells was confirmed by the change of cell morphology and evident deposition of extra-cellular matrix, accompanied by mineralization and scaffold remodeling; furthermore, all induced cell-loaded implants lost specific stemness immunophenotype expression and simultaneously upregulated genomic expression of osteogenic genes Osterix and Ostecalcin. β-TCP bio-ceramic foam scaffolds proved to be suitable carriers and hosts of canine adipose-derived MSCs, promoting not only surface attachment and proliferation, but also demonstrating strong in-vitro osteogenic potential. Although this research provides satisfactory in-vitro validation for the conceptualization and feasibility of a canine bio-active bone implant, further testing such as patient safety, large-scale reproducibility, and quality assessment are needed for regulatory compliance in future commercial clinical applications.

Hierarchically porous calcium phosphate scaffold with degradable PLGA microsphere network

Calcium phosphate cement (CPC) is widely used in orthopedics, dentistry and spine surgery because of its excellent biocompatibility, osteoconductivity, arbitrary shaping and self-setting ability. However, slow degradation rate of CPC decreases its bone regeneration efficacy. Herein, poly (lactic co-glycolic acid) microspheres (PLGAm) and wollastonite (WS) were mixed with CPC powder to prepare CPC composite pastes, and then the composite pastes were perfused into poly (lactic co-glycolic acid) network (PLGAnw) to construct composite bone repair materials. The degradation of PLGAnw generated interconnected macropores with the short side of about 468 μm along horizontal axis and the long side of about 785 μm along longitudinal axis, while PLGAm degradation generated isolated or partially connected relative smaller spherical macropores with the size range of 53–106 μm and 106–150 μm, respectively, which was same with PLGAm; in addition, CPC formed micro/nano pores after hydration, thus constructing in-situ hierarchically porous CPC composite scaffolds. Meanwhile, PLGAnw and PLGAm also significantly promoted the degradation of CPC due to the release of acidic by-products. Therefore, the introduction of PLGA network and microspheres not only can evidently accelerate degradation of CPC, but also in-situ form connected macropores and hierarchically porous after their degradation, which are expected to improve bone repair effect of CPC.

Bioinspired sandwich-like hybrid surface functionalized scaffold capable of regulating osteogenesis, angiogenesis, and osteoclastogenesis for robust bone regeneration.

Recently, strategies that focus on biofunctionalized implant surfaces to enhance bone defect healing through the synergistic regulation of osteogenesis, angiogenesis, and osteoclastogenesis have attracted increasing attention in the bone tissue engineering field. Studies have shown that the Wnt/β-catenin signaling pathway has an imperative effect of promoting osteogenesis and angiogenesis while reducing osteoclastogenesis. However, how to prepare biofunctionalized bone implants with balanced osteogenesis, angiogenesis, and osteoclastogenesis by activating the Wnt/β-catenin pathway has seldom been investigated. Herein, through a bioinspired dopamine chemistry and self-assembly method, BML-284 (BML), a potent and highly selective Wnt signaling activator, was loaded on a mussel-inspired polydopamine (PDA) layer that had been immobilized on the porous beta-tricalcium calcium phosphate (β-TCP) scaffold surface and subsequently modified by a biocompatible carboxymethyl chitosan hydrogel to form a sandwich-like hybrid surface. β-TCP provides a biomimetic three-dimensional porous microenvironment similar to that of natural cancellous bone, and the BML-loaded sandwich-like hybrid surface endows the scaffold with multifunctional properties for potential application in bone regeneration. The results show that the sustained release of BML from the sandwich-like hybrid surface significantly facilitates the adhesion, migration, proliferation, spreading, and osteogenic differentiation of MC3T3-E1 cells as well as the angiogenic activity of human umbilical vein endothelial cells. In addition to osteogenesis and angiogenesis, the hybrid surface also exerts critical roles in suppressing osteoclastic activity. Remarkably, in a critical-sized cranial defect model, the biofunctionalized β-TCP scaffold could potentially trigger a chain of biological events: stimulating the polarization of M2 macrophages, recruiting endogenous stem cells and endothelial cells at the injury site to enable a favorable microenvironment for greatly accelerating bone ingrowth and angiogenesis while compromising osteoclastogenesis, thereby promoting bone healing. Therefore, these surface-biofunctionalized β-TCP implants, which regulate the synergies of osteogenesis, angiogenesis, and anti-osteoclastogenesis, indicate strong potential for clinical application as advanced orthopedic implants.

Biological evaluation of polydopamine and chitosan composite coatings on the 3D printed porous biphasic calcium phosphate scaffold

A current, gradually growing trend is to use bioactive ceramics to develop new bone scaffolds to replace traditional bone implants. Biphasic calcium phosphate (BCP), a mixed material of hydroxyapatite and tricalcium phosphate, has limited osseointegration ability. Therefore, improving the bioactivity and osteoinductive ability of BCP scaffolds through various surface modification methods is an important issue. Polydopamine (PDA) coating, chitosan (CS) coating, and their composite coatings have been previously reported to individually possess a good ability to improve scaffold bioactivity, but few comparisons between them and the optimal coating sequence of PDA and CS have been reported. Herein, we fabricated a BCP scaffold by using a self-made 3D printer, sintered the scaffold, and then prepared PDA, CS, PDA/CS and CS/PDA coatings by solution immersion. Afterwards, the surface morphology, element composition and proportion, compressive strength and surface contact angle of the five groups of scaffolds were characterized. Finally, the adhesion, proliferation and osteogenesis-related gene expression levels of MC3T3-E1 on the five groups in vitro were evaluated in detail. The results showed that the five types of scaffolds were fabricated successfully and that the PDA/CS and CS/PDA coatings had different surface morphologies. The compressive strengths of the composite-coating groups were higher than those of the single-coating groups and the BCP group. The CCK-8 experiment revealed that the composite coatings can promote the initial adhesion and proliferation of cells. The detection results of three osteogenesis-related genes (OCN, COL-1 and Runx-2) proved that the composite coatings had a synergistic effect in promoting osteodifferentiation and that the CS/PDA coating had the greatest effect in improving cell viability and promoting osteogenic differentiation.

Effect of porosity and phase composition in 3D printed calcium phosphate scaffolds on bone tissue regeneration in vivo

Highly porous calcium phosphate (CaP) scaffolds with multiple phases were fabricated through combination of material extrusion type 3D printing process, salt-leaching, and bone cement chemistry under physiological conditions. Scaffolds with nano-sized calcium deficient hydroxy apatite (CDHA) in the core and large crystals of dicalcium phosphate dihydrate (DCPD or brushite) on the outer surface were fabricated by immersing the 3D ceramic scaffold in aqueous ‘cement solution’. In contrast to conventional CaP cement reactions where a single product is obtained, here we could achieve a composite of apatite-brushite. The composite scaffolds showed improved compressive strength without loss of porosity which was suitable for efficient bone tissue regeneration. With 65 % porosity, these scaffolds showed compressive strength of 15 MPa. The porosity of CaP scaffold was increased by applying salt-leaching technique to 3D printing, which greatly influenced the biodegradation of the scaffold in vivo. Composite scaffolds with fast degrading brushite shell showed better and faster scaffold-to-bone integration compared to apatite based scaffold. In vivo studies verified that multi-phase CaP scaffolds with bimodal pore structure induced good new bone formation behavior (85 % of coverage rate on calvaria defect site after 11 weeks of implantation) with good biodegradability (76.6 % of degradation in rabbit subdermal model after 12 weeks of implantation).

Granular honeycomb scaffolds composed of carbonate apatite for simultaneous intra- and inter-granular osteogenesis and angiogenesis.

Granular porous calcium phosphate scaffolds are used for bone regeneration in dentistry. However, in conventional granules, the macropore interconnectivity is poor and has varying size. Herein, we developed a productive method for fabricating carbonate apatite honeycomb granules with uniformly sized macropores based on extrusion molding. Each honeycomb granule possesses three hexagonal macropores of ∼290 ​μm along its diagonal. Owing to these macropores, honeycomb granules simultaneously formed new and mature bone and blood vessels in both the interior and exterior of the granules at 4 weeks after implantation. The honeycomb granules are useful for achieving rapid osteogenesis and angiogenesis.

Repair calvarial defect of osteoporotic rats by berberine functionalized porous calcium phosphate scaffold.

In this article, we propose a simple scheme of using berberine (BBR) to modify porous calcium phosphate ceramics (named PCPC). These BBR molecules regulate the crystallization of hydroxyapatite nanorods on PCPC. We found that these nanorods and the adsorbed BBR changed the interface micro-environment of PCPC by SEM images. The microenvironment of PCPC surface is essential for promoting BMSCs’ proliferation and differentiation. These results demonstrated that PCPC/BBR markedly improved the bone regeneration of osteoporosis rats. Moreover, PCPC/BBR had significantly increased the expression levels of ALP, osteocalcin and bone morphogenetic protein2 and RUNX2 in BMSCs originated from osteoporosis rats.

Bone-mimetic porous hydroxyapatite/whitlockite scaffolds: preparation, characterization and interactions with human mesenchymal stem cells

Bone-mimetic highly porous Mg-substituted calcium phosphate scaffolds, composed of hydroxyapatite (HAP) and whitlockite (WH), were synthesized by hydrothermal method at 200 °C, using calcium carbonate skeletons of cuttlefish bone, ammonium dihydrogenphosphate (NH4H2PO4) and magnesium chloride hexahydrate (MgCl2 × 6H2O) or magnesium perchlorate (Mg(ClO4)2) as reagents. The effect of Mg content on the compositional and morphological properties of scaffolds was studied by means of X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy (SEM) with energy-dispersive X-ray analysis. Structural refinements performed by Rietveld method indicated that Mg2+ ions were preferentially incorporated into the WH phase. SEM images of all prepared scaffolds showed that the interconnected structure of the cuttlefish bone was completely maintained after the hydrothermal synthesis. Results of compression tests showed a positive impact of the whitlockite phase on the mechanical properties of scaffolds. Human mesenchymal stem cells (hMSCs) were cultured on scaffolds in osteogenic medium for 21 days. Immunohistochemical staining showed that Mg-CaP scaffolds with the HAP:WH wt ratio of 90:10 and 70:30 exhibited higher expression of collagen type I and osteocalcin than pure HAP scaffold. Calcium deposition was confirmed by Alizarin Red staining. Positive effect of Mg2+ ions on the differentiation of hMSCs on porous 3D scaffolds was also confirmed by reverse transcription-quantitative polymerase chain reaction analysis.

Improving mechanical properties of porous calcium phosphate scaffolds by constructing elongated gyroid structures using digital light processing

The present study reports the manufacturing of a novel type of porous calcium phosphate scaffolds with elongated gyroid structures using digital light processing (DLP), in order to offer significantly enhanced mechanical properties. In particular, solid camphor was employed as the diluent, in order to offer sufficiently low viscosity at high solid loading for conventional layer-by-layer DLP process. Four types of porous CaP scaffolds with different percent elongation (%EL = 0, 20, 40, and 60) were manufactured, and their porous structures and mechanical properties were characterized. All porous CaP scaffolds showed that CaP walls were elongated along the z-direction, while the degree of pore elongation increased with an increase in the designed %EL. Owing to the use of controlled processing parameters, such as layer thickness and exposure time for layer-by-layer photocuring process, and carefully designed debinding process, the photocured layers could be completely bonded together with high densification after sintering at 1,200 °C for 3 h. Such elongation of a gyroid structure offered significantly enhanced mechanical properties − compressive strengths of 4.33 ± 0.26 MPa and 11.51 ± 1.75 MPa were obtained for the porous CaP scaffold with the %EL of 0 and 60, respectively.

Berberine/Ag nanoparticle embedded biomimetic calcium phosphate scaffolds for enhancing antibacterial function

Abstract In the past decade, biomimetic calcium phosphate (CaP) ceramics have been considered as practicable grafts and biomaterial substitutes in repairing jaw bone defect after tumor resection or traffic accident. Nowadays, increasing incidence of biomedical material-associated infection has raised a concern when applying these materials. In this work, a new porous CaP scaffold with antibacterial coating was proposed. This biomimetic scaffold was composited with berberine (BBR), Ag nanoparticles (nAg), and silk fibroin (SF). The microstructures and phase composition of the scaffolds were analyzed. The cytocompatibility and osteogenic potential of the prepared samples were evaluated in vitro. The scaffolds held hierarchical structure: the first-level porous CaP ceramic with micron pores ranged from 250 to 600 µm; the second-level spongy-like structure with abundant capillary pores ranged from 500 nm to 10 µm; and the third-level structure was achieved by filling BBR, nAg, and SF gel coatings into the above porous structures. The experimental results showed that the antimicrobial capability of single BBR coating is inconspicuous. However, the introduction of nAg could significantly promote the antibacterial effect of scaffolds. At the same time, such scaffolds showed improved osteoinductivity. This new biomimetic CaP scaffold with antibacterial and osteoinductive properties may be a promising candidate for bone tissue engineering.

Digital Light Processing of Freeze-cast Ceramic Layers for Macroporous Calcium Phosphate Scaffolds with Tailored Microporous Frameworks.

The objective of the present study is to demonstrate the versatility of the digital light processing (DLP) technique particularly when using a freeze-cast ceramic layer as the feedstock, which can manufacture porous calcium phosphate (CaP) scaffolds with arbitrarily designed macroporous structures with tailored microporous frameworks specially designed for bone scaffold applications. For this goal, we employed camphene-camphor as the freezing vehicle and porogen for the preparation of photocurable CaP suspensions containing diurethane dimethacrylate (UDMA) monomers. After freeze-casting, the CaP suspensions could be solidified at controlled temperatures (~33–38 °C) and then be photopolymerized by DLP. All produced CaP scaffolds fairly resembled the designed macroporous structures (the gyroid structure with two interpenetrating macropore networks). In addition, numerous micropores were created in the CaP filaments, while the microporosity increased with increasing the camphene-camphor amount from 40 vol % to 60 vol %. As a consequence, compressive strength and modulus of hierarchically porous CaP scaffolds decreased due to an increase in overall porosity. However, reasonable mechanical properties could be obtained at high porosities owing to the CaP frameworks constructed in a periodic manner. In addition, excellent water penetration capability, biocompatibility, and apatite-forming ability were obtained, which were attributed to the microporous CaP frameworks with good pore interconnectivity and large surface area.

Photocurable ceramic slurry using solid camphor as novel diluent for conventional digital light processing (DLP) process

This study presents the utility of solid camphor as a novel type of diluent for the preparation of photocurable ceramic slurries with sufficiently low viscosity at high solid loading (48 vol%), which can be applicable for the conventional digital light processing (DLP) process. The camphor addition remarkably decreased the viscosity of calcium phosphate (CaP) ceramic slurries without affecting their photopolymerization behavior. This approach could effectively mitigate the clogging of pores with residual slurries, and thus the porous structure of porous CaP scaffolds with 3D channels could be tightly controlled. Furthermore, the high densification of CaP frameworks after sintering at 1250 °C for 3 h could be achieved owing to the use of the high solid loading in the CaP slurry. The porous CaP scaffolds produced displayed high compressive strength (˜ 23.8 MPa) and modulus (˜ 276 MPa) at a high porosity of ˜ 50.6 vol%.

A carboxymethyl cellulose bone graft carrier delays early bone healing in an ovine model.

A limitation in the use of calcium phosphate (CaP) is that in its raw form, it comprises blocks or granules, which are limited in their utility for orthopedic surgery and a number of commercial bone grafts are supplied within an aqueous based carboxymethyl cellulose (CMC) putty. Our hypothesis was that CMC combined with a porous silicate-substituted CaP (SiCaP) scaffold would have no negative effect on bone formation after implantation in an ovine femoral condyle. Defects were either (a) empty or filled with (b) SiCaP granules, (c) CMC-SiCaP Putty or (d) a SiCaP press-fit dry block. Scaffolds were identical in composition and remained in vivo for 4, 8, and 12 weeks. Bone apposition rates, bone area, percentage of bone-implant contact and graft area were quantified. At 4 and 8 weeks, significantly more new bone and percentage of bone-implant contact was measured within granules when compared with both putty and block scaffolds. At 12 weeks, significantly increased bone was measured for the granules when compared with blocks and no significant difference was found when the granules and putty scaffolds were compared. Results showed the disadvantageous effect that CMC may have on early bone growth and that granules increased new bone formation when compared with a press-fit block composed of the same material.

Effect of mechanical properties on porous calcium phosphate scaffold

Abstract The effect of mechanical properties of porous calcium phosphate scaffold was examined. The scaffold is a temporary supporting structure into the patient's bone defect to enhance the development of new bones because of scaffolding declines. This study focuses on the effect of mechanical properties of porous calcium phosphate (CaP) scaffold using foam replication techniques. Sintering treatment treated at 1150°C and 1250°C were improved and the composite particles od porous calcium phosphate were homogeneously mixed and distributed. The specimen was analyzed under X-ray diffraction, SEM and compressive strength. The X-ray diffraction spectrum shows the presence of Ca10(PO4)6OH2 phases in sintered scaffolds. The formation of rod-like apatite was observed through SEM. An increase in the mechanical properties of scaffolds from 2.2MPa to up to 2.23MPa was found relative to pure collagen scaffold, while the porosity was decreased from 93.2% to 92%, indicating the potential of scaffold for bone tissue engineering or as a bone graft substitute

Porous Calcium Phosphate Ceramic Scaffolds with Tailored Pore Orientations and Mechanical Properties Using Lithography-Based Ceramic 3D Printing Technique.

This study demonstrates the usefulness of the lithography-based ceramic 3-dimensional printing technique with a specifically designed top-down process for the production of porous calcium phosphate (CaP) ceramic scaffolds with tailored pore orientations and mechanical properties. The processing parameters including the preparation of a photocurable CaP slurry with a high solid loading (φ = 45 vol%), the exposure time for photocuring process, and the initial designs of the porous scaffolds were carefully controlled. Three types of porous CaP scaffolds with different pore orientations (i.e., 0°/90°, 0°/45°/90°/135°, and 0°/30°/60°/90°/120°/150°) were produced. All the scaffolds exhibited a tightly controlled porous structure with straight CaP frameworks arranged in a periodic pattern while the porosity was kept constant. The porous CaP scaffold with a pore orientation of 0°/90° demonstrated the highest compressive strength and modulus due to a number of CaP frameworks parallel to the loading direction. On the other hand, scaffolds with multiple pore orientations may exhibit more isotropic mechanical properties regardless of the loading directions. The porous CaP scaffolds exhibited an excellent in vitro apatite-forming ability in a stimulated body fluid (SBF) solution. These findings suggest that porous CaP scaffolds with tailored pore orientations may provide tunable mechanical properties with good bone regeneration ability.

Coextrusion-Based 3D Plotting of Ceramic Pastes for Porous Calcium Phosphate Scaffolds Comprised of Hollow Filaments.

This paper demonstrates the utility of coextrusion-based 3D plotting of ceramic pastes (CoEx-3DP) as a new type of additive manufacturing (AM) technique, which can produce porous calcium phosphate (CaP) ceramic scaffolds comprised of hollow CaP filaments. In this technique, green filaments with a controlled core/shell structure can be produced by coextruding an initial feedrod, comprised of the carbon black (CB) core and CaP shell, through a fine nozzle in an acetone bath and then deposited in a controlled manner according to predetermined paths. In addition, channels in CaP filaments can be created through the removal of the CB cores during heat-treatment. Produced CaP scaffolds had two different types of pores with well-defined geometries: three-dimensionally interconnected pores (~360 × 230 μm2 in sizes) and channels (>100 μm in diameter) in hollow CaP filaments. The porous scaffolds showed high compressive strengths of ~12.3 ± 2.2 MPa at a high porosity of ~73 vol % when compressed parallel to the direction of the hollow CaP filaments. In addition, the mechanical properties of porous CaP scaffolds could be tailored by adjusting their porosity, for example, compressive strengths of 4.8 ± 1.1 MPa at a porosity of ~82 vol %. The porous CaP scaffold showed good biocompatibility, which was assessed by in vitro cell tests, where several the cells adhered to and spread actively with the outer and inner surfaces of the hollow CaP filaments.

In vitro characterization of porous calcium phosphate scaffolds capped with crosslinked hydrogels to avoid inherent brittleness

Ductile composite scaffolds can avoid being crushed during filling processes in clinical applications. Thus, this study aimed to modify brittle porous ceramic scaffolds into ductile scaffolds through hydrogel capping. The surfaces of calcium phosphate (CaP) ceramic scaffolds were effectively capped with alginate/gelatin hydrogels. The composite scaffolds were then crosslinked, subjected to vacuum drainage, and washed prior to lyophilization. The detailed controlled approach in this study was proposed with the aim to develop biocompatible composites with anisotropic open pores through the formation of a thin, homogenous, hydrogel film coating on porous ceramic scaffold surfaces. The performances of the hydrogel/CaP composite scaffolds were evaluated on the basis of their morphological characteristics, compressive strengths, and cell viabilities. Results showed that strength, toughness, and specimen integrity after cracking are strongly related to the concentration of the hydrogel cap. Strength testing results showed that the use of 50vol% alcohol as the crosslinker removal solution yielded scaffolds with high toughness and ductility. Moreover, the cracked specimen dipped in 50vol% alcohol possessed better integrity than that dipped in water only. This study successfully identified the optimal hydrogel quantity for the fabrication of biocompatible scaffolds with open connective pores. The advantages of the fabricated scaffolds indicate the relevance of the proposed method to clinical applications, such the production of fillers for successful alveolar bone augmentation.

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 β-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.