Search

Two types of synthetic carbonate apatite [potassium-containing carbonate apatite (CAK) and sodium-containing carbonate apatite (CANa)] were prepared and characterized by thermogravimetric analysis, X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy. The chemical formulas of carbonate apatite were determined to be Ca9.36K0.12(PO4)5.12(CO3)0.88(OH)1.73 and Ca8.72Na1.33(PO4)4.96(CO3)1.04(OH)1.80, respectively. Thermogravimetric analysis showed that the final weight loss at 1,200°C reached about 11.2% for CAK and 13.9% for CANa. Carbonate loss gradually occurred above 150°C and continued to 1,200°C. The crystallinity of the apatite phase was found to be much improved between 800 and 850°C for CAK and 750 and 800°C for CANa, where rapid carbonate loss occurred. A small amount of CaO formed above 900°C. For CANa, NaCaPO4 also formed above 700°C in both apatites. Although the lattice parameters of the carbonate apatites varied with temperature, the final a and c lattice parameters attained constant values of 0.9421 and 0.6881 nm. [ABSTRACT FROM AUTHOR]

Carbonate apatite (CO3Ap) block can be used as a bone substitute because it can be remodeled to new natural bone in a manner conforming with the bone remodeling process. Among the many porous structures available, honeycomb (HC) structure is advantageous for rapid replacement of CO3Ap to bone. In this study, the feasibility to fabricate a CO3Ap HC was studied, along with its initial tissue response in rabbit femur bone defect. First, a mixture of Ca(OH)2 and a wax‐based binder was extruded from a HC mold. Then the fabricated HC was heated for binder removal and carbonation at 450°C in a mixed O2–CO2 atmosphere, forming a CaCO3 HC. When the CaCO3 HC was immersed in 1 mol/L Na3PO4 solution at 80°C for 7 days, its composition changed from CaCO3 to CO3Ap, maintaining the structure of the original CaCO3 HC. Compressive strengths of the CaCO3 and CO3Ap HCs were 65.2 ± 7.4 MPa and 88.7 ± 4.7 MPa, respectively. When the rabbit femur bone defect was reconstructed with the CO3Ap HC, new bone penetrated the CO3Ap HC completely. Osteoclasts and osteoblasts were found on the surface of the newly formed bone and osteocytes were also found in the newly formed bone, indicating ongoing bone remodeling. Furthermore, blood vessels were formed inside the pores of CO3Ap HC. Therefore, CO3Ap HC has good potential as an ideal bone substitute. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1014–1020, 2019. [ABSTRACT FROM AUTHOR]

Geopolymer is a non-crystalline material based on aluminosilicate reaction exhibiting ceramic-like properties. It showed the possibility to use geopolymer as biomaterials by soaking in SBF solution to induct carbonate apatite onto the surface of samples. Carbonate apatite possesses good biocompatibility and bioactivity. The aims of this research were to study the geopolymer synthesis as a biomaterial to replace bones and the effects of Ca/P ratio on bioactivity properties of metakaolin-based geopolymers. For in vitro bioactivity test, the samples were soaked in SBF to study the influence of Ca(OH)2 contents on the surface reaction. The 14, 28, and 90 day-soaked sample surfaces were investigated using SEM, XRD, and FTIR characterization. The compressive strength of samples was also tested. The SEM micrographs revealed that the increase of Ca/P ratio resulted in the increase of the carbonate apatite on sample surfaces. FTIR results confirmed that the formation of Ca10(PO4)3(CO3)3(OH)2 was investigated. [ABSTRACT FROM AUTHOR]

The main purpose of the presented article is the preparation of novel glass-ceramics in CaO-SiO2-P2O5-MgO system and evaluation of carbonate apatite formation after soaking in TRIS-HCl buffer solution for 14 days. The investigated samples were prepared via sol-gel method and structure of the obtained samples was studied using XRD, FTIR, SEM, XPS and ICP-AES. XRD of the thermally treated samples showed that the presence of some crystalline phases is depended on the gel composition. FTIR revealed the existence of all characteristic bands for the observed crystalline phases. SEM monitored the presence of particles with different morphology. After soaking in TRIS-HCl solution, FTIR confirmed that carbonate apatite was formed on the soaked surface. The obtained data are in a good agreement with XPS analysis. The change of ions concentrations in TRIS-HCl buffer solution after immersion of the prepared glass-ceramics was recorded by ICP-AES measurements.

Chicken bone by-product has the potential to be utilized as a source of carbonate apatite (CO _3 Ap) for the preparation of bone grafts. In this study, the raw bones were cleaned with NaCl and then immersed in NaOH solution at 80 °C. After chemical treatment, the as-prepared powder was calcined in a range of 300 °C–900 °C. The results showed that calcination was useful for the complete elimination of organic residues; but, it led to increasing of crystal size, coarsening of particles, and the loss of the carbonate groups in the apatite structure. In vitro evaluation showed that CO _3 Ap prepared at the optimum temperature, 500 °C, exhibited a great biological response; such as good cell attachment, cell viability, and cell morphology. This research suggests a promising biomaterial for the fabrication of bone substitutes and could offer a solution for recycling and adding value to food waste.

Introduction: Cancer is one of the top-ranked noncommunicable diseases causing deaths to nine million people and affecting almost double worldwide in 2018. Tremendous advancement in surgery, chemotherapy, radiation and targeted immunotherapy have improved the rate of cure and disease-free survival. As genetic mutations vary in different cancers, potential of customized treatment to silence the problem gene/s at the translational level is being explored too. Yet delivering therapeutics at the required dosage only to the affected cells without affecting the healthy ones, is a big hurdle to be overcome. Scientists worldwide have been working to invent a smart drug delivery system for targeted delivery of therapeutics to tumor tissues only. As part of such an effort, few organic nanocarriers went to clinical trials, while inorganic nanoparticles (NPs) are still in development stage despite their many customizable properties. Carbonate apatite (CA), a pH sensitive nanocarrier has emerged as an efficient delivery system for drugs, plasmids and siRNAs in preclinical models of breast and colon cancers. Like hydroxyapatite (HA) which serves as a classical tool for delivery of genetic materials such as siRNA and plasmid, CA is an apatite-based synthetic carrier. We developed simplified methods of formulating CA-in-DMEM and a DMEM-mimicking buffer and HA in a HEPES-buffered solution and characterized them in terms of size, stability, protein corona (PC) composition, cytotoxicity, siRNA delivery efficiency in breast cancer cells and siRNA biodistribution profile in a mouse model of breast cancer. Methods: Particle growth was analyzed via spectrophotometry and light microscopy, size was measured via dynamic light scattering and scanning electron microscopy and confirmation of functional groups in apatite structures was made by FT-IR. siRNA-binding was analyzed via spectrophotometry. Stability of the formulation solutions/buffers was tested over various time points and at different temperatures to determine their compatibility in the context of practical usage. Cellular uptake was studied via fluorescence microscopy. MTT assay was performed to measure the cytotoxicity of the NPs. Liquid chromatography—mass spectrometry was carried out to analyze the PC formed around all three different NPs in serum-containing media. To explore biodistribution of all the formulations, fluorescence-labeled siRNA-loaded NPs were administered intravenously prior to analysis of fluorescence intensity in the collected organs and tumors of the treated mice. Results: The size of NPs in 10% serum-containing media was dramatically different where CA-in-DMB and HA were much larger than CA-in-DMEM. Effect of media was notable on the PC composition of all three NPs. All three NPs bound albumin and some common protease inhibitors involved in bone metabolism due to their compositional similarity to our bone materials. Moreover, CA also bound heme-binding proteins and opsonins. Unlike CA, HA bound different kinds of keratins. Difference in PC constitution was likely to influence accumulation of NPs in various organs including those of reticuloendothelial system, such as liver and spleen and the tumor. We found 10 times more tumor accumulation of CA-in-DMB than CA-in-DMEM, which could be due to more stable siRNA-binding and distinct PC composition of the former. Conclusion: As a nanocarrier CA is more efficient than HA for siRNA delivery to the tumor. CA prepared in a buffer containing only the mere constituents was potentially more efficient than classical CA prepared in DMEM, owing to the exclusion of interference attributed by the inorganic ions and organic molecules present in DMEM.

The replacement of hydroxy or phosphate ions in the naturally occurring inorganic material hydroxyapatite by carbonate ions leads to the properties of dental enamel and dentine that allow carnivores to cope with the stresses and forces involved in devouring their prey.

Purpose: After tooth extraction, preservation of the alveolar ridge by socket grafting attenuates bone resorption. Runt-related transcription factor 2 (RUNX2) and SP7/Osterix (OSX) are transcription factors playing an important role in osteoblast differentiation. The purpose of this study was to evaluate the effects of carbonate apatite (CO 3 Ap) on osteoblast-related gene and protein expression after socket grafting., Methods: Alveolar bone and new bone after CO 3 Ap grafting were collected at the time of implant placement. Levels of mRNA for RUNX2, SP7/OSX, bone morphogenetic protein 2 (BMP2), BMP7 and platelet derived growth factor B were determined by real-time PCR. Immunostaining was performed using antibodies against RUNX2, SP7/OSX, vimentin and cytokeratin. To evaluate bone resorption rates, cone-beam CT (CBCT) imaging was performed after socket grafting and before implant placement., Results: CBCT imaging showed that the average degree of bone resorption at the CO 3 Ap graft site was 7.15 ± 3.79%. At the graft sites, levels of SP7/OSX and BMP2 mRNA were significantly increased. Replacement of CO 3 Ap with osteoid was evident histologically, and in the osteoid osteoblast-like cells were stained for SP7/OSX and vimentin., Conclusion: These results show that gene expression of both SP7/OSX and BMP2 can be induced by CO 3 Ap, suggesting that increased expression of SP7/OSX and vimentin may be involved in the BMP pathway.

This study radiologically and histologically compared two bioresorbable bone substitutes with different compositions carbonate apatite (Cytrans ® Granules; CGs) and β-tricalcium phosphate (β-TCP) for vertical bone augmentation on a rat skull using a polytetrafluoroethylene (PTFE) tubes. This PTFE tube was placed at the center of the skull, fixed with Super Bond, and augmented with CGs or β-TCP granules. Specimens with surrounding tissue were harvested at 4, 8, and 12 weeks postoperatively, and radiological and histological evaluations were performed. The bone volume to total volume ratio (BV/TV) of the β-TCP-implanted group was markedly higher than that of the CG-implanted group at 4 and 12 weeks postoperatively. Compared to CGs, β-TCP exhibited the ability to form blood vessels into the graft material for a short period after transplantation, as well as an elevated production of collagen into β-TCP granules during the bone formation process.

Bone reconstructive surgery has become a common procedure, and bone transplantation has become the second most frequently performed tissue transplantation procedure worldwide. Therefore, the need for bone substitute materials has increased. Artificial bone substitutes exhibit osteoconductive properties and feature several advantages, including abundant resources, low cost, and low donor site morbidity. Carbonate apatite (CO3Ap) is a calcium phosphate ceramic that can be used as a synthetic bone graft. The carbonate content of this ceramic is similar to that of bone apatite. In this review, we show that carbonate apatite can be degraded given its chemical reactivity in a weakly acidic environment and through osteoclast resorption. Moreover, it is osteoconductive and promotes bone tissue formation without fibrotic tissue formation. Additionally, microstructural analysis revealed that new bone tissue is formed within the bone graft itself. [ABSTRACT FROM AUTHOR]

Abstract Carbonate apatites are sought as a bone substitute due to their biocompatibility and excellent resorbability. The present study deals with Cowrie's shell derived powder (CSDP) as natural biomaterial for bone regenerative medicine. Structural and physicochemical analysis showed that Cowrie's shells, presenting brick and mortar microstructures, were mainly composed of aragonite crystals, which were converted into poorly crystalline B-type carbonate apatite once soaked, at 37 °C, in simulated body fluid for 7 days, reflecting bioactive features. Cytotoxic assays showed that CSDP boosted human stem cell proliferation over the study time compared to nacre derived powder (NDP), used as positive control. Human stem cells adopted a flattened morphology and established physical contact with CSDP, signature of a good biocompatibility. Thus, these results suggested that CSDP presents a great interest for bone regenerative medicine, and could be a useful and versatile carrier/scaffold for bone tissue engineering or a raw material for 3D printed orthopedic devices. Highlights • Structural and physico-chemical characterizations of cowries shell are performed. • Bioactivity of Cowrie's shell derived powder (CSDP) was proven in vitro. • Biocompatibility of CSDP was also proven in vitro. • CSDP may thus be used as a biomaterial for bone regenerative medicine. [ABSTRACT FROM AUTHOR]

Abstract Objectives The aim of this present study was to investigate the effect of setting atmosphere on replacement of apatite cement with new bone both in vitro and in vivo. Material and methods Apatite cement consisting of an equimolar mixture of tetracalcium phosphate and anhydrous dicalcium phosphate was mixed with distilled water and allowed to set at 37 °C and 100% relative humidity under 0% , 5%, and 100% CO 2 atmospheres. X-Ray diffraction and Fourier Transform Infrared Spectroscopy were employed to confirm the carbonate apatite formation. Micro-CT and histological evaluation was made at 1 and 6 month(s) using twelve 10-week-old specific-pathogen-free male Wistar rats. Results B-type carbonate apatite was found when the apatite cement was set under 100% CO 2 and 5% CO 2. More carbonate apatite was formed in the case of 100% CO 2 when compared with 5% CO 2 , and none was formed under 0% CO 2. Interestingly, unreacted tetracalcium phosphate was significant when apatite cement was set under 0% CO 2 , indicating the formation of Ca-deficient hydroxyapatite. When a bone defect of rat tibia was reconstructed in these conditions of apatite cement and sintered hydroxyapatite, replacement of the apatite cement was confirmed 6 months after implantation, whereas no replacement was observed in the case of sintered hydroxyapatite. The amount of replacement of apatite cement with bone was greater, on the order of 100% CO 2 and 5% CO 2 , followed by 0% CO 2. Conclusion The results obtained in the present study demonstrated that setting atmosphere clearly plays an important role in the replacement of set apatite cement with bone. [ABSTRACT FROM AUTHOR]

Background: Studies of bone tissue engineering as a viable alternative to autogenous bone graft show promising results, although its mechanism and effectiveness remain only partially understood. Purpose: to explain the osteogenic differentiation of scaffold chitosan (Ch)–carbonate apatite (CA) in seeding with human amniotic mesenchymal stem cells (hAMSCs) on the regeneration of calvarial bone defects in rats. Materials and Methods: Shitosan-Carbonate Apatite (Ch-CA) scaffold was created by means of a freeze-drying method. Twenty Wistar rats were randomly divided into two groups: control and treatment. Defects were created in the calvarial bone of each treatment group with a scaffold subsequently implanted. After 8 weeks, the rats were terminated for histology and immunohistochemistry examination. Results: Expressions of vascular endothelial growth factor, bone morphogenetic protein2, Runt-related transcription factor 2 (RUNX2), and angiogenesis occurred earlier in the tissue-engineered group than that in the control group. An 8-week analysis also showed that the expression of RUNX2, alkaline phosphatase, osteocalcin, and collagen type 1 was at more elevated levels in the treatment group than that in the control group. Conclusion: These results showed that the combination of hAMSCs and Ch-CA scaffold may become one of the candidates for bone tissue engineering. [ABSTRACT FROM AUTHOR]

pH sensitives carbonate apatite (CA) has emerged as a targeted delivery vehicle for chemotherapeutics agent with tremendous potential to increase the effectivity of breast cancer treatment. The major challenge for intravenous delivery of drug-incorporated nanoparticles is their rapid opsonization, resulting in accumulation within the organs of reticuloendothelial system, such as liver and spleen. Therefore, surface modification by polyethylene glycol was implemented to improve the half-life of drug-particle complexes and enhance their uptake by target tissues. A simple, rapid, and sensitive triple quadrupole liquid chromatography–mass spectrometry method was developed and validated for quantification of gemcitabine in plasma, various organs and tumor tissues of mice with breast carcinoma, whereas sodium dodecyl sulfate-polyacrylamide gel electrophoresis, quadrupole-time of flight liquid chromatography–mass spectrometry and analysis by SwissProt.Mus_musculus database were performed for protein separation, identification, and homology search by comparing the de novo sequence tag. PEGylated CA exhibited almost 6-fold increase in gemcitabine accumulation in tumor with significant reduction in other organs within 1 h of intravenous administration, compared to free drug. In addition, plasma drug amount was found to be higher in PEGylated particles, implying their role in prolonging blood circulation time of particle-bound gemcitabine. Investigation of protein corona composition demonstrated notable reduction in opsonin interactions after PEGylation of CA particles. Overall, the results indicate that the composition and dynamics of protein corona subjected to alteration by PEGylation play crucial roles in affecting successful nanoparticle-based targeted delivery of a cytotoxic drug. [ABSTRACT FROM AUTHOR]

Background: Alveolar bone defects in children still have a high incidence. Conventional bone graft technique that has been used as a defect therapy is still not effective, so new techniques with tissue engineering approach are needed. Bone Morphogenetic Protein 4 (BMP4) as one of the indicators of osteogenic differentiation has not been widely studied, especially in the transplantation with combination of Stem Cells from Human Exfoliated Deciduous (SHED) and carbonate apatite. Aim and Objectives: This research aimed to determine the expression of BMP4 after SHED and carbonate apatite transplantation on Rattus norvegicus. Material and Methods: The combinations of SHED and carbonate apatite were transplanted on alveolar bone defects of 4 rats (Rattus norvegicus) as the treatment groups and another 4 rats were transplanted with carbonate apatite as the control groups. After 21 days, staining with Hematoxylin Eosin (HE) and Immunohistochemistry (IHC) BMP4 was performed. Results: BMP4 expression in the treatment groups was significantly higher when compared to the control groups. Discussion: Carbonate apatite has low crystallization rate and high osteoconductivity that produce more osteoblasts and increased BMP4 expression. Conclusion: The transplantation of SHED and carbonate apatite increased BMP4 expression as an indicator of osteogenic differentiation in rats. [ABSTRACT FROM AUTHOR]

Background: Collagen is regarded as one of the most useful biomaterials. We tried to combine collagen and carbonate apatite (CA) with some cytokines in order to enhance bone formation ability. In this study, we found that CA-collagen sponge (CA-CS) was a possible candidate of newly graft material for bone formation. Materials and Methods: CA-CS was fabricated by the following procedure. One wt% of pig hide collagen solution (Nippon Meat Packers. Inc., Tokyo, Japan) was neutralized with 0.1 N NaOH, and then mixed immediately 243 mg apatite powder with 0.06 M carbonate contents. After centrifugation at 1500 rpm for 10 min, excess water was removed, and the mixture was packed into Teflon molds (5.0 mm × 2.0 mm). Each 10 µg of basic fibroblast growth factor (bFGF) and recombinant human bone morphogenetic protein-2 (rh-BMP2) were involved in these sponges. Then these scaffolds frozen at −80°C for 2 h and dried in a freeze dry machine for 24 h. CA-CS without cytokines were also prepared as a control. Mouse osteoblast-like cell (MC3T3-E1) proliferations in these scaffolds were investigated by 3-day in vitro cell culture using MTT assay examination. Ten New Zealand rabbits (weight: 3–3.5 kg) were used in this in vivo study. After 3 weeks of placement, the scaffolds, rabbits were sacrificed, and bone formation in the sockets was evaluated histologically and histomorphometrically. Results and Conclusion: By histological observation and measurement of bone area ratio, CA-CS with cytokines showed higher bone formation ability (bFGF/CA-CS: 50.7 ± 7.3%, rh-BMP2/CA-CS: 54.2 ± 5.0%) than other groups. From the limited results of this study, it is suggested that CA collagen scaffolds with some cytokines may become an attractive scaffold for bone regeneration.

Pharmacotherapy as the mainstay in the management of breast cancer suffers from various drawbacks, including non-targeted biodistribution, narrow therapeutic and safety windows, and also resistance to treatment. Thus, alleviation of the constraints from the pharmacodynamic and pharmacokinetic profile of classical anti-cancer drugs could lead to improvements in efficacy and patient survival in malignancies. Moreover, modifications in the genetic pathophysiology of cancer via administration of small nucleic acids might pave the way towards higher response rates to chemotherapeutics. Inorganic pH-dependent carbonate apatite (CA) nanoparticles were utilized in this study to efficiently deliver various classes of therapeutics into cancer cells. Co-delivery of drugs and genetic materials was successfully attained through a carbonate apatite delivery device. On 4T1 cells, siRNAs against AKT and ERBB2 plus paclitaxel or docetaxel resulted in the largest increase in anti-cancer effects compared to CA/paclitaxel or CA/docetaxel. Therefore, these ingredients were selected for further in vivo investigations. Animals receiving injections of CA/paclitaxel or CA/docetaxel loaded with siRNAs against AKT and ERBB2 possessed significantly smaller tumors compared to CA/drug-treated mice. Interestingly, synergistic interactions in target protein knock down with combinations of CA/AKT/paclitaxel, CA/ERBB2/docetaxel were documented via western blotting.

While several treatment strategies are applied to cure breast cancer, it still remains one of the leading causes of female deaths worldwide. Since chemotherapeutic drugs have severe side effects and are responsible for development of drug resistance in cancer cells, gene therapy is now considered as one of the promising options to address the current treatment limitations. Identification of the over-expressed genes accounting for constitutive activation of certain pathways, and their subsequent knockdown with specific small interfering RNAs (siRNAs), could be a powerful tool in inhibiting proliferation and survival of cancer cells. In this study, we delivered siRNAs against mRNA transcripts of over-regulated cell adhesion molecules such as catenin alpha 1 (CTNNA1), catenin beta 1 (CTNNB1), talin-1 (TLN1), vinculin (VCL), paxillin (PXN), and actinin-1 (ACTN1) in human (MCF-7 and MDA-MB-231) and murine (4T1) cell lines as well as in the murine female Balb/c mice model. In order to overcome the barriers of cell permeability and nuclease-mediated degradation, the pH-sensitive carbonate apatite (CA) nanocarrier was used as a delivery vehicle. While targeting CTNNA1, CTNNB1, TLN1, VCL, PXN, and ACTN1 resulted in a reduction of cell viability in MCF-7 and MDA-MB-231 cells, delivery of all these siRNAs via carbonate apatite (CA) nanoparticles successfully reduced the cell viability in 4T1 cells. In 4T1 cells, delivery of CTNNA1, CTNNB1, TLN1, VCL, PXN, and ACTN1 siRNAs with CA caused significant reduction in phosphorylated and total AKT levels. Furthermore, reduced band intensity was observed for phosphorylated and total MAPK upon transfection of 4T1 cells with CTNNA1, CTNNB1, and VCL siRNAs. Intravenous delivery of CTNNA1 siRNA with CA nanoparticles significantly reduced tumor volume in the initial phase of the study, while siRNAs targeting CTNNB1, TLN1, VCL, PXN, and ACTN1 genes significantly decreased the tumor burden at all time points. The tumor weights at the end of the treatments were also notably smaller compared to CA. This successfully demonstrates that targeting these dysregulated genes via RNAi and by using a suitable delivery vehicle such as CA could serve as a promising therapeutic treatment modality for breast cancers.

Subcutaneous calcifications can lead to complications, including pain, inflammation, ulceration and immobilization. Studies on the pathophysiology of mineral compositions and effective treatment modalities are limited. We therefore studied 14 patients with subcutaneous calcifications. Mineral material was collected and analysed by Fourier transform infrared spectrometry. Blood analyses were run to evaluate systemic alterations of mineral metabolism. Carbonate apatite (CAP) was found to be the single constituent in the majority of patients (n = 9, 64.3%), 3 cases (21.4%) had a composition of CAP and calcium oxalate dihydrate and one case had a combination of CAP and magnesium ammonium phosphate, whereas CAP was the major component in all 4 cases. Only one case showed predominantly calcium oxalate. Thus, CAP was found to be the only or predominant component in most cases of subcutaneous calcifications. Chemical analyses of the mineral compositions may aid in the development of new treatment regimes to improve the solubility of mineral components and to decrease extraosseous calcifications. [ABSTRACT FROM AUTHOR]

The purpose of this study is to analyze the co-existence effect of 30 wt.% TCP-BG phases on degradation and precipitation behaviors of PLLA based composite scaffold in biological media. First, phase separation method was used to synthesize of the pure PLLA and the trinary composite scaffolds, and second they were immersed in SBF solution for 45 days. Subsequently, the degradation and precipitation characteristic were investigated by analyzing of pH value and weight changes of the immersed samples, the ability of biological products formation and the change of relative molecular weight of PLLA matrix as function of the degradation time. Finally, the experimental data of relative molecular weight change were verified by Han and Pan model and comparisons were made between them. Results have represented precipitation of huge amount of carbonate apatite on surface of the composite scaffold, and also the acidity of SBF media changes moderately which is prove better bioactivity properties compare to the pure PLLA scaffold. The results of comparison with the model point to quiet good agreement between them in early stage of degradation. So, the consequences suggest that the TCP-BG/PLLA composite scaffold have great potential to be applied in bone replacements or repairs. [ABSTRACT FROM AUTHOR]

An important component of phosphorite (phosphate rock) is carbonate apatite, as it is required for phosphorous fertilizer production due to its increased phosphate solubility caused by carbonate substitution in the apatite mineral lattice. High phosphate concentrations in municipal wastewater treatment plants are commonly reduced by precipitating iron phosphate by addition of iron chloride. We investigated the possibility of precipitating carbonate apatite from a potential range of phosphate concentrations that could be available from municipal wastewater treatment plants with anaerobic digestion reactors (5 mM-30 mM). Synthetic phosphate solutions at neutral pH were mixed in batch experiments with a calcium carbonate solution produced by dissolving calcite in contact with carbon dioxide gas, with and without carbonate apatite seed. Batch experiments were used to identify the carbonate apatite supersaturation ranges for homogeneous and heterogeneous nucleation and the precipitates analyzed with Raman spectroscopy, powder X-ray diffraction, inorganic carbon coulometry and scanning electron microscopy. Some precipitates contained carbonate weight fractions within the range reported for geological phosphate rock (1.4-6.3 wt %). The precipitates were spherical, poorly crystalline carbonate apatite, suggesting an amorphous precursor transformed to a poorly crystalline carbonate apatite without changing morphology. [ABSTRACT FROM AUTHOR]

Biphasic calcium phosphate consisting of carbonate apatite and β-tricalcium phosphate (β-TCP) is an excellent bone substitute with controllable bioresorbability. Fabrication of biphasic calcium phosphate with self-setting ability is expected to enhance the potential of applicability as bone substitute. In this study, mixtures of α-TCP/β-TCP powder after carbonation period 1, 3, and 5 h with 1.0 M NaHCO 3 were prepared. These powders were mixed with 0.25 M Na 2 HPO 4 at a P/L ratio of 2, and then hardened at 37 °C and 100% RH up to 24 h. XRD patterns and FT-IR spectrum showed that the resulting hardened cement consisted of biphasic carbonate apatite and β-TCP. Diametral tensile strength of the cement decreased with the carbonation period. [ABSTRACT FROM AUTHOR]

Stem cell from Human Exfoliated Deciduous Teeth (SHED) is a source of stem cells that is easy to obtain. The application of SHED can be used for repairing damaged teeth, bone regeneration, and treatment of neural tissue injury. Scaffold can be used as a carrier for application of SHED and also increase the cell growth and regeneration of damaged tissue. Carbonate apatite and hydroxyapatite are material which commonly used as scaffold. The aim of this study was to evaluate the potential proliferation of SHED in carbonate apatite scaffold and hydroxyapatite scaffold as candidate biomaterials in bone tissue engineering. SHED was obtained from dental pulp of primary extracted teeth. SHED was seeding in carbonate apatite and hydroxyapatite scaffold for 7 days. The proliferation of SHED were determined using Scanning Electron Microscope (SEM). The average number of SHED was higher in carbonate apatite scaffold compared to hydroxyapatite scaffold. Combination of SHED and carbonate apatite scaffold has higher proliferation potency compare with SHED and hydroxyapatite. [ABSTRACT FROM AUTHOR]

Carbonate apatite (CO3Ap) block, which is a bone replacement used to repair defects, was fabricated through a dissolution-precipitation reaction using a calcium hydrogen phosphate dihydrate (DCPD) block as a precursor. When the DCPD block was immersed in NaHCO3 or Na2CO3 solution at 80 °C, DCPD converted to CO3Ap within 3 days. β-Tricalcium phosphate was formed as an intermediate phase, and it was completely converted to CO3Ap within 2 weeks when the DCPD block was immersed in Na2CO3 solution. Although the crystal structures of the DCPD and CO3Ap blocks were different, the macroscopic structure was maintained during the compositional transformation through the dissolution-precipitation reaction. CO3Ap block fabricated in NaHCO3 or Na2CO3 solution contained 12.9 and 15.8 wt % carbonate, respectively. The diametral tensile strength of the CO3Ap block was 2 MPa, and the porosity was approximately 57% regardless of the carbonate solution. DCPD is a useful precursor for the fabrication of CO3Ap block. [ABSTRACT FROM AUTHOR]