scholarly journals First successful stabilization of consolidated amorphous calcium phosphate (ACP) by cold sintering: toward highly-resorbable reactive bioceramics

2020 ◽  
Vol 8 (4) ◽  
pp. 629-635 ◽  
Author(s):  
Marina Luginina ◽  
Roberto Orru ◽  
Giacomo Cao ◽  
David Grossin ◽  
Fabien Brouillet ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Bioactive Compounds ◽  
Amorphous Calcium Phosphate ◽  
Calcium Phosphates ◽  
Ionic Composition ◽  
Bone Substitutes ◽  
Sintering Conditions

An adequate tuning of amorphous calcium phosphates ionic composition and cold sintering conditions allowed the first successful stabilization of these bioactive compounds. These results show promise for the setup of highly-resorbable bone substitutes.

Effect of Synthesis Temperature and Ca/P Ratios on Specific Surface Area of Amorphous Calcium Phosphate

2016 ◽  
Vol 721 ◽  
pp. 172-176 ◽  
Author(s):  
Jana Vecstaudza ◽  
Janis Locs
Keyword(s):  
Calcium Phosphate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Amorphous Calcium Phosphate ◽  
Calcium Phosphates ◽  
Synthesis Temperature ◽  
Molar Ratios ◽  
Different Temperatures ◽  
Low Crystalline

Amorphous and low crystalline calcium phosphates are prospective candidates for bone implant manufacturing. Amorphous calcium phosphate (ACP) preparation technologies could be improved in terms of specific surface area (SSA) of obtained products. Current study is dedicated to the effect of synthesis temperature and Ca and P molar ratios (Ca/P) on SSA of ACP. Higher SSA can improve bioactivity of biomaterials. ACP was characterized by XRD, FT-IR, SEM and BET N2 adsorption techniques. Spherical nanoparticles (<45 nm in size) were obtained independently of initial Ca/P ratio and synthesis temperature. For the first time comparison of SSA was shown for ACP obtained at different temperatures (0 °C and 20 °C) and Ca/P molar ratios (1.5, 1.67 and 2.2).

scholarly journals Ultrasonic application and spray drying during amorphous calcium phosphate synthesis

2019 ◽  
Vol 8 (4) ◽  
pp. 711-714
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Calcium Phosphate ◽  
Spray Drying ◽  
Amorphous Calcium Phosphate ◽  
Calcium Phosphates ◽  
Calcium Content ◽  
Synthesis Process ◽  
Particle Sizes ◽  
Ultrasound Application

Hydroxyapatite, amorphous calcium phosphates, calcium triphosphate and calcium octaphosphate are the main components present in bones and teeth. Calcium phosphates are easily synthesized, playing an important role in regenerative medicine, being able to be used as bone implants. There are different ways of synthesizing phosphates, the most commonly used being wet chemical method. The objective of this work was to study the influence of the use of ultrasound and spray drying on the synthesis of amorphous calcium phosphate. Two synthetic variants were studied. One without ultrasound application and the other with ultrasound application. The samples obtained were characterized by X-ray diffraction, FTIR spectroscopy and scanning electron microscopy. The particle size by electron microscopy and the calcium content by atomic absorption was determined. The results showed that when spray drying is applied, particle sizes of less than 261 nm are obtained in the samples synthesized without ultrasound application, being less than 59 nm in the samples synthesized with ultrasound application. The statistical analysis by ANOVA showed significant differences between the particle sizes of the samples synthesized without ultrasound application and the samples synthesized by applying ultrasound. In both cases the particles were spherical. The results obtained show that the application of ultrasound during the synthesis process decreases the particle size, increasing the surface area, which favors the spray drying process.

Thermokinetic Investigation of the Drying Conditions on Amorphous Calcium Phosphate

2017 ◽  
Vol 758 ◽  
pp. 204-209
Author(s):  
Agnese Brangule ◽  
Līga Avotiņa ◽  
Artūrs Zariņš ◽  
Mihails Haļitovs ◽  
Kārlis Agris Gross ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Crystalline Structure ◽  
Amorphous Calcium Phosphate ◽  
Freeze Drying ◽  
Calcium Phosphates ◽  
Drying Condition ◽  
Drying Conditions

The present work investigated dried calcium phosphate powders which still retain an amorphous or poorly crystalline structure under a variety of conditions. In previous studies, freeze-drying was found to be the optimum drying condition. However, several publications, as well as our previous studies, have shown that calcium phosphate amorphous, or a poorly crystalline structure, can retain their structure even if the samples are dried immediately after synthesis up to 200°C. In our study, we used the thermokinetic studies FTIR and XRD and showed that the samples are amorphous, or poorly crystalline, but were unable to answer the questions: Is there a difference between the differently dried amorphous calcium phosphates? What are the optimum drying conditions under which the amorphous calcium phosphate (ACP) structure loses the physically bounded water, but still retains the chemically bounded water?

Effect on Drying Conditions on Amorphous Calcium Phosphate

2014 ◽  
Vol 631 ◽  
pp. 99-103 ◽  
Author(s):  
Agnese Brangule ◽  
Kārlis Gross
Keyword(s):  
Particle Size ◽  
Calcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Intermediate Phase ◽  
Calcium Phosphates ◽  
Ftir Spectra ◽  
The Body ◽  
Drying Methods ◽  
Dry Conditions ◽  
Drying Conditions

Amorphous calcium phosphate (ACP) plays an important role in the body and can be used as an intermediate phase for forming calcium phosphates. All ACPs are thermodynamically unstable compounds, unless stored in dry conditions or at low temperature (-18oC), and spontaneously undergo transformation to crystalline calcium phosphates (CaP). This work will investigate the influence of drying on the stability of ACP. ACPs powders were prepared by wet synthesis; mixing solution made of Ca (NO3)2∙4H2O and 30% ammonia with (NH4)2HPO4 and (NH4)2CO3 solution at room temperature. The suspension was stirred, filtered and washed several times with deionized water containing ammonia. ACP samples were dried at different conditions and with different drying agents (DA). XRD and FTIR spectra showed poorly crystallinity powders after drying. Some FTIR spectra indicated residual organic compounds from drying. The Rietveld’s method and Schrrer’s relationship estimated the particle size (0.5 – 20 nm) of ACP. Thermogravimetry (TG) revealed that the moisture (7% – 25%) is released upon drying, and the drying agents have no significant effect on. The drying methods are ordered to show which the most effective for removing moisture. By changing the drying conditions, it is a possible to obtain poorly crystalline ACPs with different particle size and moisture content.

Mesenchymal Stem Cell Proliferation and Morphological Analysis on Interconnected Macroporous Structures

2007 ◽  
Vol 330-332 ◽  
pp. 1129-1132 ◽  
Author(s):  
S. Teixeira ◽  
H.M. Fernandes ◽  
J. de Boer ◽  
M.P. Ferraz ◽  
F.J. Monteiro
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Maxillofacial Surgery ◽  
Bone Substitutes ◽  
Critical Parameters ◽  
Calcium Phosphate Ceramics ◽  
Natural Bone ◽  
Bone Substitute Materials

Calcium phosphate ceramics are widely used as bone substitutes since they are biocompatible and bioactive. Given that their chemical composition is close to natural bone, calcium phosphate ceramics are promising bone substitute materials in orthopaedics, maxillofacial surgery and dentistry. Hydroxyapatite (HA) and tricalcium phosphate (TCP) are the most commonly used calcium phosphates, because their calcium/phosphorus (Ca/P) ratios are close to that of natural bone and they are relatively stable in physiological environment. Furthermore, other critical parameters must be accomplished when designing a biomaterial for bone regeneration, namely: pore size, shape and interconnectivity [1]. Porosity is one of the most important factors since it influences the adhesion, migration nutrient supply and ultimately, proliferation of mesenchymal stem cells. In this study, HA scaffolds with controlled porosity were obtained and their capacity to support human and rat mesenchymal stem cells attachment and proliferation was evaluated.

Part II - Microstructural and Physical of Calcium Phosphate Biomaterials Obtained from Natural Raw Materials

2016 ◽  
Vol 881 ◽  
pp. 147-152
Author(s):  
Daiara Floriano-Silva ◽  
Nelson Heriberto Almeida Camargo ◽  
Camila Thais Mamani ◽  
Priscila Ferraz Franczak ◽  
Marli Baltazar Roesler Eckstein ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Open Porosity ◽  
Raw Materials ◽  
Calcium Phosphates ◽  
Microstructural Characterization ◽  
Bone Substitutes ◽  
Molar Ratio ◽  
Dental Applications ◽  
Grain Coalescence ◽  
Cell Adhesion And Proliferation

Calcium phosphate bioceramics obtained from raw materials are potential bone substitutes in orthopedic and dental applications. Calcium phosphates attained from calcareous shells using wet methods provide an interconnected microporous framework, shown to be promising and contribute to cell adhesion and proliferation. This study aimed to characterize three different calcium phosphate ratio compositions: (i)1.4, (ii)1.6 and (iii)1.7 molar, sintered for 2 hours at 1100°C and 1200°C. Scanning electron microscopy field effect [FEG] and confocal were used to assess microstructural characterization and Arthur method to determine open porosity. FEG and confocal analyses showed good grain coalescence, sinterability and well defined interfaces for all Ca/P molar at 1100°C and 1200°C. Open porosity and hydrostatic density exhibit better results when using Ca/P molar ratio (iii)1.7 at 1100°C. The results showed that open porosity is related to Ca/P ratio and by temperature. As the Ca/P increases so does the open porosity. Inversely occurs for temperature. As the temperature increases the porosity decreases and in parallel, the grain size increases.

Three Dimensional Macroporous Calcium Phosphate Scaffolds for Bone Tissue Engineering

2007 ◽  
Vol 361-363 ◽  
pp. 947-950 ◽  
Author(s):  
S. Teixeira ◽  
S.M. Oliveira ◽  
M.P. Ferraz ◽  
F.J. Monteiro
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Maxillofacial Surgery ◽  
Three Dimensional ◽  
Bone Substitutes ◽  
The Body ◽  
Major Constituent ◽  
Porous Hydroxyapatite ◽  
Calcium Phosphate Ceramics ◽  
Natural Bone

Calcium phosphate ceramics are widely used as bone substitutes since they are biocompatible and bioactive. Having a chemical composition close to natural bone, calcium phosphate ceramics are promising bone substitute materials in orthopaedics, maxillofacial surgery and dentistry. Hydroxyapatite (HA) and tricalcium phosphate (TCP) are the most commonly used calcium phosphates, because their calcium/phosphorus (Ca/P) ratios are close to that of natural bone and they are relatively stable in physiological environment. HA is a major constituent of bone materials and is resorbed after a long time of residence in the body. In this work, highly porous hydroxyapatite scaffolds were produced by polymer replication method and their properties evaluated by Scanning Electron Microscopy (SEM) and micro computerized tomography ()-CT).

scholarly journals Nanocomposites based on apatitic tricalcium phosphate and autofibrin

2021 ◽  
Vol 57 (4) ◽  
pp. 413-423
Author(s):  
I. E. Glazov ◽  
V. K. Krut’ko ◽  
R. A. Vlasov ◽  
O. N. Musskaya ◽  
A. I. Kulak
Keyword(s):  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Calcium Phosphates ◽  
Fibrin Clot ◽  
Combined Effect ◽  
Morphological Properties ◽  
Maturation Time ◽  
Soluble Calcium

Nanocomposites based on apatitic tricalcium phosphate in an autofibrin matrix were obtained by precipitation at a Ca/P ratio of 1.50, pH 9 and a maturation time from 30 min to 7–14 days. The resorbability of nanocomposites was determined by the composition of calcium phosphates, which, during long-term maturation, formed as the calcium-deficient hydroxyapatite with a Ca/P ratio of 1.66, whereas biopolymer matrix favored the formation of more soluble calcium phosphates with a Ca/P ratio of 1.53–1.59. It was found that the fibrin clot stabilized, along with apatitic tricalcium phosphate, the phase of amorphous calcium phosphate, which after 800 °C was transformed into resorbable α-tricalcium phosphate. Citrated plasma inhibited the conversion of apatitic tricalcium phosphate into stoichiometric hydroxyapatite, which also facilitated the formation of resorbable β-tricalcium phosphate after 800 °C. The combined effect of the maturation time and the biopolymer matrix determined the composition, physicochemical and morphological properties of nanocomposites and the possibililty to control its extent of resorption

scholarly journals Enamel Remineralization and Dentine Tubules Occlusion by Bioactive Formulations Based on Ion-Doped Nanohydroxyapatite and Precursor Nanoparticles.

2021 ◽  
Author(s):  
Andrei Cristian Ionescu ◽  
Lorenzo Degli Esposti ◽  
Michele Iafisco ◽  
Eugenio Brambilla
Keyword(s):  
Health Care ◽  
Calcium Phosphate ◽  
Bioactive Compounds ◽  
Amorphous Calcium Phosphate ◽  
Representative Sample ◽  
Dentinal Tubules ◽  
First Time ◽  
Phosphate Compounds

Abstract Recent health care products are based on formulations claimed to provide enamel remineralization and dentinal tubules occlusion through calcium-phosphate bioactive nanocompounds ( ion-doped hydroxyapatite and precursor nanoparticles). This study aimed to test and characterize for the first time the structure and composition of a representative sample of remineralizing toothpastes and topical mousses available on the market. The enamel remineralization and dentinal tubules occlusion efficacy of tested formulations were investigated in vitro. Formulations were characterized in terms of water- and acid-insoluble fractions, and PXRD, FTIR, and EDS analyses were performed to determine their composition and investigate the presence of bioactive compounds and doping elements. All formulations containing Ca-P bioactive nanocompounds showed remineralizing ability, notably when hydroxyapatite and amorphous calcium phosphate compounds were doped with small amounts of CO3-, F, Mg, and Sr. Topical mousse formulations showed a higher tubules occlusion capability than toothpastes, independently from their composition. In conclusion, all tested formulations could express remineralizing potential both on enamel and dentin thanks to the presence of biomimetic Ca-P compounds. The presence of doping elements or CPP-ACP seems essential to allow such performances.

scholarly journals The Antimicrobial Action of Silver Halides in Calcium Phosphate

2014 ◽  
Vol 631 ◽  
pp. 384-389 ◽  
Author(s):  
Daina Kalnina ◽  
Karlis Agris Gross ◽  
Pavels Onufrijevs ◽  
Edvins Dauksta ◽  
Vizma Nikolajeva ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Calcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Silver Iodide ◽  
Silver Chloride ◽  
Calcium Phosphates ◽  
Silver Halide ◽  
Silver Bromide ◽  
Silver Halides ◽  
Carbonated Apatite

Silver halides represent a yet unexplored avenue for imparting antimicrobial activity in calcium phosphates. Silver halide colloids were added to calcium phosphate. Concurrent melting of silver halides and crystallization of carbonated apatite was achieved by heating to increase the silver halide surface area available to bacteria.Pseudomonas aeruginosa were more sensitive to silver iodide and silver bromide than Staphylococcus aureus. Silver iodide demonstrated greater activity than silver bromide. Silver chloride did not produce an antibacterial response. Both amorphous calcium phosphate and carbonated apatite displayed similar antibacterial activity when accompanied by silver halides. It is thought that amorphous calcium phosphate dissolves more readily and increases the bioavailability of the silver halide particles. Silver iodide displays a greater antibacterial response of all silver halides, with a response that is improved in a more resorbable matrix.

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