Papers by Keyword: Carbonated Apatite

Abstract: Bioactivity analysis in simulated body fluid (SBF) is an experiment or protocol conducted to evaluate the bioactive properties of a sample without involving cells. The bioactive property is claimed based on the formation of apatite layer after immersion in SBF. This analysis consumes expensive chemical reagents and requires complex procedure in preparing and refreshing the solution. Therefore, the aim of this study was to identify significant alteration of refreshing time in the 1.5× SBF to form an apatite layer on a polydopamine (PDA) grafted stainless steel (SS316L) disk. The SS316L disks were pre-treated and grafted with a PDA layer to equip the bioinert metal surface with a bioactive film. The PDA grafted disks were subjected to bioactivity analysis in SBF for 7 days at different refreshing time (24 h, 48 h, 72 h and not refreshed up to 7 d). The surfaces were then characterised by FTIR, SEM-EDX, and contact angle analyses to determine its chemical composition, morphology and wettability properties. The PDA grafted disks that been subjected to 48 h refreshing time in SBF produced homogenous apatite formation with less agglomeration, closest theoretical Ca/P ratio and high hydrophilicity, suggesting the formation of preferable apatite layer with a reduction in the number of refreshing time.Bioactivity analysis in simulated body fluid (SBF) is an experiment or protocol conducted to evaluate the bioactive properties of a sample without involving cells. The bioactive property is claimed based on the formation of apatite layer after immersion in SBF. This analysis consumes expensive chemical reagents and requires complex procedure in preparing and refreshing the solution. Therefore, the aim of this study was to identify significant alteration of refreshing time in the 1.5× SBF to form an apatite layer on a polydopamine (PDA) grafted stainless steel (SS316L) disk. The SS316L disks were pre-treated and grafted with a PDA layer to equip the bioinert metal surface with a bioactive film. The PDA grafted disks were subjected to bioactivity analysis in SBF for 7 days at different refreshing time (24 h, 48 h, 72 h and not refreshed up to 7 d). The surfaces were then characterised by FTIR, SEM-EDX, and contact angle analyses to determine its chemical composition, morphology and wettability properties. The PDA grafted disks that been subjected to 48 h refreshing time in SBF produced homogenous apatite formation with less agglomeration, closest theoretical Ca/P ratio and high hydrophilicity, suggesting the formation of preferable apatite layer with a reduction in the number of refreshing time.

Abstract: Osteogenesis and degradability of bioresorbable biphasic gypsum-carbonated apatite granules (BPG) were investigated. Three different sizes of gypsum, 300-600 μm (small), 600-1000 μm (medium) and 1000-2000 μm (large), denoted as S, M and L respectively, were developed through the crushing and sieving method. Exposure of gypsum granules in carbonate and phosphate sources formed BPG through dissolution and precipitation mechanism. BPG was firstly examined by X-ray Diffractometer (XRD) and Fourier Transform Infrared Spectrometer (FTIR) to confirm its phase and chemical composition respectively. In-vitro cell proliferation, alkaline phosphatase (ALP) activity and adhesion of human osteoblast (hFOB) were investigated for osteogenesis evaluation. Degradability in phosphate buffer saline (PBS) was characterized by weight loss whereas apatite mineralization on the BPG surface was examined using Scanning Electron Microscope (SEM). BPG with 300-600 μm and 600-1000 μm enhanced osteogenic differentiation of hFOB and accelerated differentiation process better than 1000-2000 μm as indicated by cell proliferation and ALP activity. Good hFOB adhesion was observed on all BPG surfaces. The weight loss of L and M was 68% and 59%, respectively, which are higher than S at only 32%, indicating faster degradation of large BPG compared to smaller granules upon immersion for 35 days. This in turn, suggested the ionic dissolution of BPG which has contributed to the apatite formation on its surface. The results suggest, the BPG mimicked the bone matrix, exhibited good osteogenesis and degradability, which might be used as a potential candidate for bone tissue engineering.

Abstract: The purpose of this study was to prepare biphasic granules containing gypsum and carbonated apatite at low temperatures. The biphasic granules were prepared using dissolution-precipitation technique at three different temperatures 30°C, 40°C and 50°C. Characterization of the biphasic granules was determined by multiple analytical methods such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR), and CHN Analysis. The obtained granules were determined by XRD as biphasic granules containing bone apatite and gypsum. The cross-section of biphasic granules was observed by SEM. The formed bone apatite was identified as B-Type carbonated apatite using FTIR The carbonate content in biphasic granules fabricated at 30°C, 40°C and 50°C were recorded by CHN analysis as 5.0 wt%, 6.1 wt% and 6.25 wt%, respectively.

Abstract: ab initio simulations were employed to investigate the crystal structure of carbonated apatite (CAp). Two possible sites for the carbonate ions in the apatite lattice were considered: carbonate substituting for OH^- ion (type-A) and for PO₄^3- ion (type-B). A combined type-AB substitution was also proposed and numerous possible charge compensation mechanisms were treated. The results show that the most stable type-A CAp had its carbonate triangular plane almost parallel to c-axis, making an angle of about 2° at z = 0.46. In the most stable type-B CAp structure, the nearest Ca (2) ion was replaced by a sodium ion and the carbonate group was lying almost flat in b/c-plane. Of all the models considered, mixed substitution type-AB where two carbonate ions replacing one phosphate group and one hydroxyl group shows the most stable structure.

Abstract: Human teeth (HT) are natural composites which consist of nanohydroxyapatite (HAp) arranged in lamellae and bound to collagen. In present study, prepared HT powders with different ages were characterized by X-Ray Diffraction (XRD), Fourier transform infrared (FT-IR) and thermogravimetric anlysis (TGA) techniques. HT at age ranges of 1-10, 11-20, 21-30, 31-40, 41-50 and 51-60 years old were selected for tests. To prepare samples, human teeth were washed in boiling water for 1 h and left in 1 M KOH solution for 6 h to remove any organic material. After HT samples were cleaned with ultrasonic in ethanol, they were then finely grounded using agate mortar. The results from XRD indicate that the major diffraction peaks of all samples with different ages were very closely identified to that of stoichiometric HAp. All HT powders were found to be nanocrystalline structure. Furthermore, it was found that the decrease in HAp crystallinity seem to increase with higher age of 31-40 years old. To investigate chemical structure confirmed by FT-IR, All HT powders showed the band positions and function groups, which are similar to that of HAp. group found in chemical structure indicates the structure of carbonated apatite. TGA results were found that the increase of weight loss seem to increase with higher age.

Abstract: Carbonated apatite (CHA) is commonly considered a promising synthetic material for biomedical applications in orthopedic and dental surgery due to its biocompatibility, bioresorption and bioactivity. CHA5, CHA37 and CHA90 powders were synthesized from wet method and the DRX patterns showed that the crystallinity and particle size of CHA samples increased proportionally with the synthesis temperature. Powder extracts medium were obtained from each sample to interact with MC3T3-E1 osteoblastics cells. It was evaluated morphology, citotoxicity, pH and Ca²⁺ concentration. Citotoxicity assays showed high metabolic activity on all samples when compared to control. The polygonal shaped and the confluent monolayer observed in control cells progressively changed according to the crystallinity increase of samples. Cells under mitosis and spindle-like shaped where the main alterations observed. In addition the cell viability could be sensitive to the acid reactivity and crystallinity of carbonated apatite samples.

Abstract: The process of dental caries is dynamic and continuous, with periods of de- and remineralization of the tooth structure occurring over time. When the remineralization potential is superior to demineralization, the caries process can be stopped and early caries lesions can recover. Moreover, the remineralization potential will be increased if active components are added to a dentifrice. Therefore, the aim of this study was to re-evaluate the remineralizaton potential of a dentifrice containing nano-sized carbonated apatite using pH cycling, which simulates the oral environment. Artificial incipient caries was induced on bovine tooth specimens, which were treated with 4 dentifrices containing several concentrations of nano carbonated apatites with pH cycling. The remineralization effect was evaluated at each step by measuring the Vickers Hardness Number, and obtaining SEM and CLSM images of the enamel surface. The micro hardness of the enamel surface increased after the pH cycling treatment of the dentifrices. The dentifrice containing 5% n-CAPs showed the highest level of remineralization followed by 0%, 15% and 30%. One-way ANOVA indicated a significant difference in remineralization between the dentifrice containing 5% and 30% n-CAPs. SEM and CLSM also demonstrated observable differences in each step. From this study, the fluoride dentifrice containing 5% n-CAPs was effective in remineralizing an artificial incipient caries lesion. In conclusion, the dentifrice containing 5% nano carbonated apatites and 25% silica was the most effective in remineralizing early caries lesion.

Abstract: Hydroxy carbonated apatite (HCA) powders were prepared by precipitation from a modified SBF solution (5x M-SBF). The ionic concentrations were 5 times higher than in human blood plasma with the exception of Mg2+ and HCO3 - concentrations that were reduced in order to accelerate crystal growth. Spheroaggregates of HCA platelets with molar (Ca+Mg)/P ratios ranging from 1.44 to 1.56 were obtained after precipitation at 50 °C. The crystallite size in c-direction was approximately 20 nm and depending on the precipitation time a CO3 2- content of 1.8 to 5.2 wt.-% was determined. Using this low temperature precipitation method, HCA powders with a high specific surface area of 83 m2/g and a composition and crystallite size close to those of the mineral phase of human bone were obtained.

Abstract: The effect of carbonated apatite powder size on the carbonated apatite embedded on titanium alloy was studied. The process was conducted using superplastic deformation method at 750oC and initial pressure of 34MPa. In order to evaluate the characteristics of the resulting embedded layer, X-ray diffraction method was conducted followed with microstructure characterization. From X-ray diffraction characterization, it can be concluded that small stress layers of carbonated apatite were resulted for all samples with different initial powder size. In addition, initial powder size of carbonated apatite only significantly influences the intensity of diffraction peak for certain plane of crystal structure. From the experimental results, it can also be concluded that superplastic deformation can be used as an alternative method for the coating process of bio apatite material on titanium alloy substrate

Abstract: Osteoinduction by biomaterials that initially do not contain bone morphogenetic proteins and other growth factors has been shown to be a real phenomenon by many investigators in the past two decades. Although it is well-known that a material needs to meet very specific requirements in terms of physico-chemical and structural properties in order to be osteoinductive, the underlying mechanism of osteoinduction is not fully unraveled yet. In the present study we investigated parameters which are of importance for the osteoinductive potential of biomaterials by comparing four biphasic calcium-phosphate and a carbonated apatite ceramic. The results showed that the presence of micropores, by which the specific surface area of a material is increased, is essential for the material’s osteoinductivity. However, if the surface area is too high, or material is too resorbable because of its chemical composition, the implant might degrade and lose its shape. In that case, ectopic bone formation does not occur, as a relatively stable surface is needed to facilitate new bone growth.