Thermokinetic Investigation of the Drying Conditions on Amorphous Calcium Phosphate

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?

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Effect on Drying Conditions on Amorphous Calcium Phosphate

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.631.99 ◽

2014 ◽

Vol 631 ◽

pp. 99-103 ◽

Cited By ~ 4

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.

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Preparation of Scaffolds of Amorphous Calcium Phosphate and Bacterial Cellulose for Use in Tissue Regeneration by Freeze-Drying Process

Biointerface Research in Applied Chemistry ◽

10.33263/briac111.73577367 ◽

2020 ◽

Vol 11 (1) ◽

pp. 7357-7367

Keyword(s):

Calcium Phosphate ◽

Bacterial Cellulose ◽

Tissue Regeneration ◽

Amorphous Calcium Phosphate ◽

Freeze Drying ◽

Calcium Phosphates ◽

Synthetic Polymers ◽

Drying Process ◽

Cytotoxicity Studies ◽

The One

The elaboration of scaffolds for use in tissue regeneration processes plays an important role in the area of biomaterials. Natural and synthetic polymers, together with calcium phosphates, form suitable compounds for these studies because their combinations favor the union of the properties of both materials, such as their biocompatibility, biofunctionality, shape, porosity, and mechanical properties. The objective of this work was to develop a scaffold of amorphous calcium phosphate and bacterial cellulose, applying a freeze-drying process. The results demonstrated the feasibility of scaffolds elaboration applying the freeze-drying methodology. The formulation that presented the best results was the one that contained amorphous calcium phosphate (50%), bacterial cellulose gel (20%), and sodium alginate (30%). Cytotoxicity studies showed that the studied formulation did not present cytotoxicity, promoting cell viability.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.721.172 ◽

2016 ◽

Vol 721 ◽

pp. 172-176 ◽

Cited By ~ 3

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).

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Ultrasonic application and spray drying during amorphous calcium phosphate synthesis

Letters in Applied NanoBioScience ◽

10.33263/lianbs84.711714 ◽

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.

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

Journal of Materials Chemistry B ◽

10.1039/c9tb02121c ◽

2020 ◽

Vol 8 (4) ◽

pp. 629-635 ◽

Cited By ~ 1

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.

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Nanocomposites based on apatitic tricalcium phosphate and autofibrin

Proceedings of the National Academy of Sciences of Belarus Chemical Series ◽

10.29235/1561-8331-2021-57-4-413-423 ◽

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

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The Antimicrobial Action of Silver Halides in Calcium Phosphate

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.631.384 ◽

2014 ◽

Vol 631 ◽

pp. 384-389 ◽

Cited By ~ 4

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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Charge State of Silver Halide Colloids Determines the Antibacterial Activity in Amorphous Calcium Phosphate

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.587.74 ◽

2013 ◽

Vol 587 ◽

pp. 74-79 ◽

Cited By ~ 2

Author(s):

Kārlis Gross ◽

Daina Kalnina ◽

Zivile Stankeviciute ◽

Vizma Nikolajeva

Keyword(s):

Calcium Phosphate ◽

Amorphous Calcium Phosphate ◽

Silver Iodide ◽

Calcium Phosphates ◽

Silver Halide ◽

Antibacterial Action ◽

X Ray Diffraction ◽

Silver Halides ◽

Diffraction Patterns

Removal of bacteria is important not only at implantation, but after long-term implant/prosthesis use. This requires strategies that employ different approaches for combating bacteria. Halides have the potential of an additional mechanism, and together with silver may provide a more powerful antibacterial strategy. Silver iodide was synthesized as colloids with a positive and negative charge and incorporated into an amorphous calcium phosphate (ACP) to provide a possible greater antibacterial action. Colloids were characterized by FTIR spectroscopy and the charge measured by zeta potential. Phase analysis by X-ray diffraction patterns confirmed the formation of b-AgI nanoparticles. Minimum inhibitory concentrations (MIC) for preventing the growth ofStaphylococcus aureusandPseudomonas aeruginosawere lower for ACP containing negatively charged silver halides. Amorphous calcium phosphates with silver iodide exhibited good inhibition capacity. Solubility was determined by the increase in pH and the release of silver after 48 hours. The minimum bactericidal concentration (MBC) was also determined. This work has shown the effect of AgI charge in amorphous calcium phosphate for providing antibacterial action.

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Biphasic Calcium Phosphate Biomaterials: Stem Cell-Derived Osteoinduction or In Vivo Osteoconduction? Novel Insights in Maxillary Sinus Augmentation by Advanced Imaging

Materials ◽

10.3390/ma14092159 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2159

Author(s):

Giovanna Iezzi ◽

Antonio Scarano ◽

Luca Valbonetti ◽

Serena Mazzoni ◽

Michele Furlani ◽

...

Keyword(s):

Calcium Phosphate ◽

Maxillary Sinus ◽

Biphasic Calcium Phosphate ◽

Calcium Phosphates ◽

Three Dimensional ◽

Sinus Augmentation ◽

Native Bone ◽

Maxillary Sinus Augmentation ◽

Posterior Maxilla

Maxillary sinus augmentation is often necessary prior to implantology procedure, in particular in cases of atrophic posterior maxilla. In this context, bone substitute biomaterials made of biphasic calcium phosphates, produced by three-dimensional additive manufacturing were shown to be highly biocompatible with an efficient osteoconductivity, especially when combined with cell-based tissue engineering. Thus, in the present research, osteoinduction and osteoconduction properties of biphasic calcium-phosphate constructs made by direct rapid prototyping and engineered with ovine-derived amniotic epithelial cells or amniotic fluid cells were evaluated. More in details, this preclinical study was performed using adult sheep targeted to receive scaffold alone (CTR), oAFSMC, or oAEC engineered constructs. The grafted sinuses were explanted at 90 days and a cross-linked experimental approach based on Synchrotron Radiation microCT and histology analysis was performed on the complete set of samples. The study, performed taking into account the distance from native surrounding bone, demonstrated that no significant differences occurred in bone regeneration between oAEC-, oAFMSC-cultured, and Ctr samples and that there was a predominant action of the osteoconduction versus the stem cells osteo-induction. Indeed, it was proven that the newly formed bone amount and distribution decreased from the side of contact scaffold/native bone toward the bulk of the scaffold itself, with almost constant values of morphometric descriptors in volumes more than 1 mm from the border.

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Reversal of Root Caries with Casein Phosphopeptide-Amorphous Calcium Phosphate and Fluoride Varnish in Xerostomia

Caries Research ◽

10.1159/000516176 ◽

2021 ◽

pp. 1-10

Author(s):

Ahmed Sleibi ◽

Anwar R. Tappuni ◽

Aylin Baysan

Keyword(s):

Calcium Phosphate ◽

Amorphous Calcium Phosphate ◽

Primary Root ◽

Severity Index ◽

Salivary Flow ◽

Root Caries ◽

Carious Lesions ◽

Group 2 ◽

Casein Phosphopeptide ◽

Group 1

Different formulas of topical fluoride have been used to manage root carious lesions. This clinical trial aimed to investigate the efficacy of a dental varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride compared with fluoride alone in reversing/arresting root caries in xerostomic patients over 1 year. A total of 80 patients (age range 45–92 years) with primary root caries (n = 184 root carious lesions) and unstimulated salivary flow rate of <0.2 mL/min were randomly allocated to receive either dental varnish containing CPP-ACP and 5% fluoride (group 1: MI varnish; GC, Japan) (n = 41, 83 lesions), or dental varnish with 5% fluoride alone (group 2: NUPRO White; Dentsply, USA) (n = 39, 101 lesions). Clinical assessments with Severity Index (SI) for root caries, DIAGNOdent measurements, and varnish application were carried out at baseline, 3, 6, and 12 months. Standard oral hygiene instructions with 1,450 ppm fluoride toothpastes were provided for both groups. After 3 months, 63.9% (n = 46) of root caries in group 1 became hard (SI: 0) compared with 39.3% (n = 35) in group 2 (p < 0.01). After 6 and 12 months, the differences in SI were insignificant (group 1, n = 60, 83.3%) (group 2, n = 66, 74.2%) (p = 0.36), and (group 1, n = 60, 89.6%) (group 2, n = 67, 81.7%, n = 1 soft, 1.2%) (p = 0.29), respectively. In both groups, noncavitated leathery lesions were more likely to become hard when compared to the cavitated root caries. A significant decrease in plaque index, surface roughness, lesion dimension, and DIAGNOdent readings with a significant increase in lesion distance from the gingival margin was reported in both groups (p < 0.05). This study has provided evidence that fluoride dental varnish either with or without calcium and phosphate has the potential to arrest/reverse root caries, especially noncavitated lesions for patients with xerostomia.

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