Calcium Phosphate Composites Research Articles

Light transmittance and polymerization kinetics of amorphous calcium phosphate composites.

This study investigated light transmittance and polymerization kinetics of experimental remineralizing composite materials based on amorphous calcium phosphate (ACP), reinforced with inert fillers. Light-curable composites were composed of Bis-EMA-TEGDMA-HEMA resin and ACP, barium glass, and silica fillers. Additionally, a commercial composite Tetric EvoCeram was used as a reference. Light transmittance was recorded in real-time during curing, and transmittance curves were used to assess polymerization kinetics. To obtain additional information on polymerization kinetics, temperature rise was monitored in real-time during curing and degree of conversion was measured immediately and 24h post-cure. Light transmittance values of 2-mm thick samples of uncured ACP composites (2.3-2.9%) were significantly lower than those of the commercial composite (3.8%). The ACP composites presented a considerable transmittance rise during curing, resulting in post-cure transmittance values similar to or higher than those of the commercial composite (5.5-7.9 vs. 5.4%). The initial part of light transmittance curves of experimental composites showed a linear rise that lasted for 7-20s. Linear fitting was performed to obtain a function whose slope was assessed as a measure of polymerization rate. Comparison of transmittance and temperature curves showed that the linear transmittance rise lasted throughout the most part of the pre-vitrification period. The linear rise of light transmittance during curing has not been reported in previous studies and may indicate a unique kinetic behavior, characterized by a long period of nearly constant polymerization rate. The observed kinetic behavior may result in slower development of polymerization shrinkage stress but also inferior mechanical properties.

Tailoring the pore structure and property of porous biphasic calcium phosphate ceramics by NaCl additive

This study investigated the effects of NaCl additive on the phase composition, pore structure and mechanical property of porous biphasic calcium phosphate (BCP) ceramics, which were prepared by freeze-casting. The results indicated that the addition of NaCl promoted transformation of β-tricalcium phosphate to hydroxyapatite in the BCP ceramics; the OH group in HA phase of BCP ceramic was partially replaced by chloride ion. As the mass fraction of NaCl in the slurry increased from 0 to 3%, the porosity of obtained porous BCP ceramics decreased from 77.76% to 60.22%; the average width of dendritic pores increased from 74.37µm to 111.27µm; the compressive strength achieved threefold increase. As the amount of NaCl additive reached 4.5%, the porosity, pore width, and compressive strength of the porous BCP ceramics were comparable with those modified by 3% NaCl. NaCl is regarded as an effective additive to tailor the pore structure and property of freeze-cast porous ceramics.

One-year water-ageing of calcium phosphate composite containing nano-silver and quaternary ammonium to inhibit biofilms.

Dental composites are commonly used restorative materials; however, secondary caries due to biofilm acids remains a major problem. The objectives of this study were (1) to develop a composite containing quaternary ammonium dimethacrylate (QADM), nanoparticles of silver (NAg), and nanoparticles of amorphous calcium phosphate (NACP), and (2) to conduct the first investigation of the mechanical properties, biofilm response and acid production vs water-ageing time from 1 day to 12 months. A 4 × 5 design was utilized, with four composites (NACP-QADM composite, NACP-NAg composite, NACP-QADM-NAg composite, and a commercial control composite), and five water-ageing time periods (1 day, and 3, 6, 9, and 12 months). After each water-ageing period, the mechanical properties of the resins were measured in a three-point flexure, and antibacterial properties were tested via a dental plaque biofilm model using human saliva as an inoculum. After 12 months of water-ageing, NACP-QADM-NAg had a flexural strength and elastic modulus matching those of the commercial control (P>0.1). Incorporation of QADM or NAg into the NACP composite greatly reduced biofilm viability, metabolic activity and acid production. A composite containing both QADM and NAg possessed a stronger antibacterial capability than one with QADM or NAg alone (P<0.05). The anti-biofilm activity was maintained after 12 months of water-ageing and showed no significant decrease with increasing time (P>0.1). In conclusion, the NACP-QADM-NAg composite decreased biofilm viability and lactic acid production, while matching the load-bearing capability of a commercial composite. There was no decrease in its antibacterial properties after 1 year of water-ageing. The durable antibacterial and mechanical properties indicate that NACP-QADM-NAg composites may be useful in dental restorations to combat caries.

A first report of hydroxylated apatite as structural biomineral in Loasaceae - plants' teeth against herbivores.

Biomineralization provides living organisms with various materials for the formation of resilient structures. Calcium phosphate is the main component of teeth and bones in vertebrates, whereas especially silica serves for the protection against herbivores on many plant surfaces. Functional calcium phosphate structures are well-known from the animal kingdom, but had not so far been reported from higher plants. Here, we document the occurrence of calcium phosphate biomineralization in the South-American plant group Loasaceae (rock nettle family), which have stinging trichomes similar to those of the well-known stinging nettles (Urtica). Stinging hairs and the smaller, glochidiate trichomes contained nanocrystalline hydroxylated apatite, especially in their distal portions, replacing the silica found in analogous structures of other flowering plants. This could be demonstrated by chemical, spectroscopic, and diffraction analyses. Some species of Loasaceae contained both calcium phosphate and silica in addition to calcium carbonate. The intriguing discovery of structural hydroxylated apatite in plants invites further studies, e.g., on its systematic distribution across the family, the genetic and cellular control of plant biomineralization, the properties and ultrastructure of calcium phosphate. It may prove the starting point for the development of biomimetic calcium phosphate composites based on a cellulose matrix.

Effect of calcium phosphate ceramic substrate geometry on mesenchymal stromal cell organization and osteogenic differentiation

The composition of calcium phosphate (CaP) ceramics in combination with surface features have been shown to influence biological performance, and micro- and nano-scale topography is known to stimulate osteogenic differentiation of mesenchymal stromal cells (MSCs). In view of this, adipose tissue derived MSCs were cultured on CaP disks featuring hemispherical concavities of various sizes (440, 800 or 1800 μm diameter). It was hypothesized that (i) surface concavities would promote cell proliferation, cellular organization within the concavities, and osteogenic differentiation, as a result of a more pronounced 3D micro-environment and CaP nucleation in concavities, and (ii) MSC proliferation and osteogenic differentiation would increase with smaller concavity size due to more rapidly occurring 3D cell–cell interactions. We found that concavities indeed affect cell proliferation, with 440 μm concavities increasing cell proliferation to a larger extent compared to 800 and 1800 μm concavities as well as planar surfaces. Additionally, concavity size influenced 3D cellular organization within the concavity volume. Interestingly, concavity size promoted osteogenic differentiation of cells, as evidenced by increased osteocalcin gene expression in 440 μm concavities, and osteocalcin staining predominantly for 440 and 800 μm concavities, but not for 1800 μm concavities and only slightly for planar surface controls.

Synthesis of β-TCP and CPP containing biphasic calcium phosphates by a robust technique

Biphasic calcium phosphate (BCP) compositions consisting of β-tricalcium phosphate (β-TCP) and calcium pyrophosphate (CPP) are potential biodegradable ceramics for bone regeneration. The present work demonstrates the formation of such dense ceramics by first preparing the precursors of nano-sized, amorphous, and equiaxed calcium pyrophosphate particles, and then sintering the precursors at 900°C to transform them into desired BCP. However, if the complex of calcium tripolyphosphate was used, only CPP could be generated. It was also observed that the incorporation of Mg2+ had several effects on the resulting products including: (1) promoting the generation of meso-porous precipitates; (2) favoring the formation of β-TCP instead of CPP; (3) reducing the grain size and increasing the density of the sintered ceramics, and (4) enhancing the negative electric charge of the BCP surface. Thus, the as-prepared BCP ceramics can serve as potential bone substitute materials in orthopedic applications.

Butterflies of the Cambrian benthos? Shield position in bradoriid arthropods

Mode of preservation and method of recovery strongly influences our understanding of the life habits of extinct organisms. Bradoriid arthropods were abundant, and diverse members of early Cambrian ecosystems and most life reconstructions display these animals with the two shields of the carapace open in a ‘butterfly’ configuration. This favoured reconstruction is largely based on the abundance of ‘crack-out’ specimens preserved in this position (e.g. Kunmingella from the early Cambrian of China). In contrast, large collections of acid processed bradoriids from the Arrowie Basin of South Australia (Cambrian Stage 3) are preserved with a narrow gape at the ventral margin or completely closed with the carapace folded along the dorsal midline. The relative abundance of conjoined, closed (or partially closed) specimens from the lower Cambrian Hawker Group succession suggests that at least some bradoriid taxa were capable of withdrawing appendages and tightly closing the shields, challenging the common view that the majority of bradoriids usually held their carapaces open in a ‘butterfly’ configuration during life. New data show that layers of the bradoriid carapace are continuous through the dorsal fold with no evidence for complex articulating structures as in ostracod hinges. The relatively pliable, sclerotized or lightly mineralized calcium phosphate composition of the carapace and the simple, flexible dorsal fold facilitated opening and closing of the shields. Despite not being closely related, ostracods share close biomechanical and ecological similarities with bradoriids. The evolution of more complex articulating hinge structures – together with well-developed musculature – in ostracods during the Early Ordovician, may have provided more efficient means for shield articulation and movement, thus promoting the ecological success of ostracods throughout the Phanerozoic.

Calcium Phosphate Composition Affects Ureteroscopic Laser Lithotripsy.

The effects of stone composition on transurethral lithotripsy (TUL) have not been sufficiently elucidated. The purpose of this study was to identify how calcium phosphate stone composition impacts TUL. Two hundred eighty-nine cases of semi-rigid and/or flexible TUL for upper urinary tract calculi were reviewed retrospectively. Inclusion criteria were a preoperative assessment by noncontrast computed tomography (NCCT) and a stone composition analysis. Small stones and those without calcium composition were excluded. Stone core radiodensity (SCR) was measured by taking the average of the upper 3 of 5 points in the proximity of the center of the stone on NCCT. Fifty-three patients with calcium phosphate composition (CaP) and 118 patients with calcium oxalate and without phosphate composition were eligible for analysis. SCR was significantly higher in the CaP group (p＜0.01). The CaP patient group needed a significantly longer operation time (p＝0.014) and more laser energy (p＝0.085), and tended to have a lower rate of complete lithotripsy (p＝0.096) and higher incidence of postoperative pyelonephritis (p＝0.181). Stones containing calcium phosphate are harder, demand more laser energy, and require a longer operating time. NCCT evaluation can estimate stone composition preoperatively, and may be a useful tool for predicting operative outcomes.

Zn release behavior of amorphous calcium phosphate and alginate gel composite

Event Abstract Back to Event Zn release behavior of amorphous calcium phosphate and alginate gel composite Tomohiro Uchino1, Tomomi Nakanome1 and Tomoya Mori1 1 Nihon University, College of Engineering, Japan Introduction: Some cements for bone substitute has an advantage on injectable and regardless of bone defect appearance. Amorphous calcium phosphate (ACP) is considered a precursor to bone hydroxyapatite (HAp; Ca10(PO4)6(OH)2)[1]. Zn is a trace element as bone formation[2]. Alginate gel is a non-toxic material that can serve as a medium for controlled active ingredients release[3][4]. In this study, we prepared injectable Zn-containing gel composites consisting of alginate and ACP. Then, we try to investigate the Zn release behavior from the composites in an environment of mimicking bone metabolism. The obtained samples were injected and immersed in an acetic acid buffer solution (AcBu) mimicking the peripheral environment of active osteoclasts or in a simulated body fluid (SBF: Kokubo’s solution) mimics the environment of active osteoblasts. After immersing the samples in AcBu or SBF solutions, the Zn release behavior and characterization of the samples were investigated. Materials and Methods: CaCl2∙H2O and NaH2PO4 solutions were mixed at a 1:1 molar ratio of Ca and P. The mixed solution was added to a stirred NaOH solution at less than 4ºC and a pH10. The precipitates were filtered, washed with acetone, and freeze dried. ZnSO4 solution and sodium alginate solution (Alg) were mixed. This solution was mixed with obtained ACP powder with an emulsion needle (AlgZn-Ca). For another preparation, the ACP powder and Alg were mixed first, and then, mixed with Zn solution (CaAlg-Zn). These AlgZn-Ca or CaAlg-Zn gel composite sample was injected into 30 cm3 of AcBu or SBF at 37ºC for 1, 3, and 7 days. Immersing for 1 and 3 days, 10 cm3 of immersed solutions were exchanged for new solution. After immersing 7 days, gel composite samples were dried at room temperature. Zn, Ca and P concentrations in AcBu and SBF before and after immersing the samples were measured. For alginate gel characterization, Zn or Ca containing alginate gel was synthesized by dropped Zn or Ca solution into alginate solution. Results and Discussion: The Zn release behavior of these gel composites is shown in Fig. 1. The Zn release rate of ZnAlg-Ca was slower than CaAlg-Zn in AcBu. Similarly, Ca and P were released from the composites in AcBu. After immersing ZnAlg-Ca in AcBu for 7days, 80% of Zn was released. In contrast, after immersed these samples in SBF for 7 days, less than 1% of Zn was released from these samples. The Zn release rate would be controlled by alginate cross-linked Zn2+. Alginate forms a gel with divalent cations (Ca2+, and Zn2+) as cross-linking points. From DTA measurement, exothermal peak was detected at 530ºC of Zn2+ containing gel, in contrast, the peak was detected at 700ºC of Ca2+ containing gel (Fig. 2). The ZnAlg-Ca sample formed alginate gel by Zn2+ would make Zn slower release. Conclusion: The alginate gel was effective for controlling Zn release and making injectable samples. The gel composite samples were expected to be a new controlled release injectable bone substitutes. JSPS KAKENHI Grant Number 26861688.

Formation of hybrid materials based on calcium phosphate deposit on carbon fiber scaffold

Event Abstract Back to Event Formation of hybrid materials based on calcium phosphate deposit on carbon fiber scaffold Quentin Picard1, Lise Guichaoua1, Sandrine Delpeux-Ouldriane1, Nathalie Rochet2, Jérôme Chancolon1, Franck Fayon3, Fabienne Warmont1 and Sylvie Bonnamy1 1 CNRS / University of Orleans, ICMN, France 2 INSERM/BIPOA, IBV, France 3 CNRS, CEMHTI, France Introduction: Due to their breathability, specific mechanical properties and biocompatibility, activated carbon clothes (ACC) have previously been considered for hard and soft tissue implanting. However, their poor biological activity restricts their extensive use in medical applications and therefore needs to be enhanced[1]-[3]. Carbon fiber-reinforced calcium phosphate (CaP) composites, combining the highly biocompatible, osteoconductive and bioactive CaP matrix with the properties of carbon fibers, are promising bioceramic material, which could be particularly useful in the reconstruction of bone defects[3]. Experimental Methods: CaP coated ACC are obtained by sono-electrodeposition process using cathodic polarization. Ca(NO3)2, 4H2O and NH4H2PO4 are used as electrolyte. The influence of electrochemical parameters is connected to the amount, microtexture, structure and chemical composition of CaP phases. The materials biocompatibility was determined by culturing primary human osteoblast-cells (HOST) in contact with CaP/ACC hybrid materials. Results and Discussion: The mass uptake tends to a limit corresponding to the decrease of nucleation sites. The current density gouverns the CaP characteristics: amount, morphology and chemical composition. Indeed, the quantity of deposit is proportional to the applied current density (thickness ranging from 10 nm to 1 µm). During CaP deposition, water electrolysis regime gouverns the pH decrease at the carbon electrode surface and consequently leads to CaP precipitation. This process gives biomimetic and uniform CaP coated fibers. Their CaP chemical compositions can be modulated to get similar ones to natural bones. SEM, HRTEM and FTIR characterizations show that the coating consists in a mixture of octacalcium phosphate and plate-like carbonated HA phases at low current densities and needle-like carbonated HA with calcium carbonate phases at high current densities. 1H and 31P MAS NMR of deposits confirm the presence of carbonated HA with a minority of disordered CaP phase. First biological results through in vitro osteoblast culture have evidenced the cell viability on hybrid materials (Fig. 1). Figure 1: SEM image of human osteoblasts cultured at 7 days in the presence of CaP/ACC hybrid material obtained at low current density. Conclusion: The sono-electrodeposition process allows to tailor the thickness, morphology (platelets or needles), chemical composition and to get biomimetic CaP coatings consisting mainly in carbonated HA with minor disordered CaP phases. Close to natural bone chemical composition, the CaP/ACC hybrid materials show a good interaction with primary HOST and therefore could be used as bioactive scaffold for bone regeneration. European Program PF7_IRSES « ABREM »; Region Centre Val-de-Loire project: Hybrid bio-actives materials for bone reconstruction

Effects of nano-biphasic calcium phosphate composite on bioactivity and osteoblast cell behavior in tissue engineering applications

In this paper, preparation, bioactivity, and osteoblast cell behavior of cortical bone derived nano-biphasic calcium phosphate (nano-BCP) are presented. The calcined bovine bone samples with the addition of di-ammonium hydrogen phosphate were heated at 700°C for 100 min, and thus nano-BCP with the composition of 63/37 hydroxyapatite (HA)/β-tricalcium phosphate (β-TCP) was produced. Scanning electron microscopy (SEM) images, energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis of immersed samples in simulated body fluid (SBF) solution showed that a uniform layer was formed on the surface after 7 days with the chemical composition of HA. The results indicated that the nano-BCP sample developed excellent bioactivity after 28 days. The nano-BCP samples showed better cell proliferation compared to pure HA samples. After 7 days in cell culture, the prepared nano-BCP (HA/β-TCP) exhibited the maximum proliferation of the MG-63 osteoblast cells.

Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review.

In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes.

Effect of Phase Composition of Calcium Phosphate (CaP) on Bioactivity of Osteon-like Composite Scaffolds

From compositional perspective, natural bone is a kind of inorganic and organic composite material; while from structural perspective, the basic structural unit of cortical bone is vascularized osteon. In this study, based on the biomimetic principle, a tissue-engineered construct was created to stimulate the basic building block of cortical bone-osteon with complex structure. To achieve this goal, a bi-layered polycaprolactone (PCL)/CaP com- posite scaffold was produced via a novel two-step fabrication process in the combination of electrospinning and twin screw extrusion. Its inner hollow tube was made of electrospun nanofibers, allowing the formation of a con- fluent layer of endothelial cells (MS-1) to resemble the Haversian canal, and its outer layer consisted of spiral PCL/CaP microfilament with high porosity, facilitating the proliferation and differentiation of pre-osteoblasts (MC3T3-E1) to form bone-like tissues. To explore the effect of material composition on scaffold bioactivity, three composite scaffolds with different outer layers were fabricated, including PCL, PCL/biphasic calcium phosphate (BCP) and PCL/β-tricaclium phosphate (β-TCP). And then the influences of scaffold composition on the behaviors of pre-osteoblasts were further investigated. Compared to PCL and PCL/β-TCP, significantly more cell growth and higher calcium deposition are found on PCL/BCP scaffolds, precisely controlling the spatial distribution of different cells. Taken together, this bi-layered PCL/BCP scaffold partially mimics the complex structure of osteon, showing a promising potential in the orthopedic application.

CNTs as ion carriers in formation of calcium phosphate coatings

Surface functionalisation of carbon nanotubes (CNTs) provides possibility of employing them in the biomedical industry as drug/growth factor carriers improving healing of a patient after injury. Carbon nanotubes are also very perspective nanomaterials as reinforcement in composites because of their mechanical properties. In the present work, single wall CNTs (SWCNTs), single wall/double wall (SW/DWCNTs) and multiwall CNTs (MWCNTs) functionalised with –COOH, –OH and –NH2 groups were tested as ion carriers in electrodeposition and as reinforcements in the composite calcium phosphate coatings. In our research, new composite coatings with Ca/P ratios ranging from 1·0 to 1·50 were obtained during electrodeposition in electrolytic solutions containing –COOH functionalised SWCNTs and MWCNTs. Amorphous calcium phosphates were fabricated in electrolytic solutions containing –NH2 functionalised MWCNTs, while no coating was fabricated in electrolytes containing –OH functionalised SW/DWCNTs. The structure and kind of functionalised groups of CNTs had an influence on the type, morphology and thickness of electrodeposited calcium phosphate coatings.

Composite Calcium Phosphate Coatings on Mg Alloy for Medicine

The high-tech method of creating anticorrosion calcium phosphate coating on the magnesium alloy MA8 (MgMnCe) has been developed. As was demonstrated by the volumetry method the sealing of the layer formed on the surface of Mg alloy using plasma electrolytic oxidation by superdispersed polytetrafluoroethylene substantially reduced the rate of the corrosion process. Here, the surface of the calcium phosphate layer containing hydroxyapatite (Ca/P = 1.61) remains biologically active. Studies of architectonics of the surface of innate immune cells have been performed in vitro.

Synthesis, composition, and properties of calcium phosphate–gelatin composites

Solid phases have been synthesized in Ca(NO3)2–(NH4)2HPO4–gelatin–H2O systems with the variable ratio Ca/P and variable pH at biopolymer concentrations of 0–2 g/L. Physicochemical studies show that calcium phosphate and gelatin based composites precipitate under our experimental conditions. The mineral composition and the amount of organic component in the precipitate are dictated by pH in the initial reaction system. The dissolution rates of composites in 0.9% NaCl are found to be two to three times the value for stoichiometric hydroxylapatite (HA) and increase in going to samples containing octacalcium phosphate (OCP) and brushite.

The Crosstalk between Osteoclasts and Osteoblasts Is Dependent upon the Composition and Structure of Biphasic Calcium Phosphates

Biphasic calcium phosphates (BCPs), consisting of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), exhibit good biocompatibility and osteoconductivity, maintaining a balance between resorption of the biomaterial and formation of new bone. We tested whether the chemical composition and/or the microstructure of BCPs affect osteoclasts (OCs) differentiation and/or their ability to crosstalk with osteoblasts (OBs). To this aim, OCs were cultured on BCPs with HA content of 5, 20 or 60% and their differentiation and activity were assessed. We found that OC differentiation is partially impaired by increased HA content, but not by the presence of micropores within BCP scaffolds, as indicated by TRAP staining and gene profile expression. We then investigated whether the biomaterial-induced changes in OC differentiation also affect their ability to crosstalk with OBs and regulate OB function. We found that BCPs with low percentage of HA favored the expression of positive coupling factors, including sphingosine-kinase 1 (SPHK1) and collagen triple helix repeat containing 1 (Cthrc1). In turn, the increase of these secreted coupling factors promotes OB differentiation and function. All together our studies suggest that the chemical composition of biomaterials affects not only the differentiation and activity of OCs but also their potential to locally regulate bone formation.

Editorial on the original article entitled "3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration" published in the Biomaterials on February 14, 2014.

The paper entitled "3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration" published in the Biomaterials recently illuminated the way to make particular scaffolds with calcium phosphate (CaP) powder, phosphoric acid, type I collagen and Tween 80 in low temperature. After the optimal concentration of each component was determined, the scaffolds were evaluated in a critically sized murine femoral defect model and exhibited good material properties. We made some related introduction of materials applied in 3D printing for bone tissue engineering based on this article to demonstrate the current progress in this field of study.

Exceptional preservation of clam shrimp (Branchiopoda, Eucrustacea) eggs from the Early Cretaceous Jehol Biota and implications for paleoecology and taphonomy

AbstractFossil eggs of clam shrimps (Spinicaudata) are rare and little attention has been paid to the study of their shape and microstructures. Here, we report the discovery of exceptionally preserved three-dimensional eggs from numerous specimens ofEosestheria ellipticaChen, 1976 from the lacustrine Early Cretaceous Yixian Formation in western Liaoning, China. These three-dimensionally preserved fossil eggs display a spherical shape with smooth surface, part of the tertiary envelope, and possibly the first embryonic cuticle, which were previously unknown or ambiguous. The eggs are abundant and assumed to be attached to the exopod as in extant Spinicaudata. Moreover, the exceptional three-dimensional preservation and delicate preparation of slices of the eggs allowed us to document the microstructures and elemental composition of fossil eggs of clam shrimps from the Jehol Biota. Energy dispersive spectroscopy of the fossilized envelope revealed a calcium phosphate composition. However, the egg contents display two completely different elemental compositions. Some exhibit the same elemental composition as the envelope, whereas others has been replaced by alumino-silicate. The taphonomic process is also briefly discussed in this paper.

Biphasic Calcium Phosphate Scaffold with Interconnected Pores Prepared by Sintering Calcium Phosphate Bone Cement

This proposal aims to develop a newly, stable, excellent and environmental process of manufacturing scaffolds with virtually identical biphasic calcium phosphate compositions. Calcium phosphate cements (CPCs), which combines calcium orthophosphate powders with a liquid leading to a paste that hardens spontaneously at low temperatures, have potential to be used as a porous template for dental bone grafting substitutes [1,2]. Such newly developed sintering processes having the bone grafts with properties of bioactivity or even bioresorbability would be applied in many clinical setting. Template materials combine calcium orthophosphate powders with a liquid leading to a paste that hardens spontaneously at low temperatures. Hence, CPCs could be applied as scaffolds to support cell/tissue growth [3, 4]. This paper studies CPC scaffolds processing by foaming cement's paste state in which was added phasic stabilizer of magnesia and foaming agent of sucrose. The X-ray diffraction was performed to identify the phases of bone grafting substitutes, and we also used scanning electron microscope to observe the structure and pores of bone grafting substitutes. The cell viability about biocompatibility of developed bone grafting substitutes was examined. The results showed that our bone grafting substitutes produced steady final biphasic products consisting of hydroxyapatite (HA) and beta-tricalcium phosphates (β-TCP). We observed interconnected pores and highly porosity in microstructure of the bone grafting substitutes. The cell viability was over 70 % to make sure that the bone grafting substitutes has excellent biocompatibility. In conclusion, using the slurry of calcium phosphate cements (CPCs) and pores forming agent set into a porous template would be a useful process for manufacturing bone graft substitutes.