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.

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

2013 ◽  
Vol 587 ◽  
pp. 74-79 ◽  
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.

Miscibility Gaps in Fused Salts

1970 ◽  
Vol 25 (10) ◽  
pp. 1484-1489 ◽  
Author(s):  
Giorgio Flor ◽  
Cesare Sinistri
Keyword(s):  
Silver Iodide ◽  
Sodium Tungstate ◽  
Silver Chloride ◽  
Reciprocal System ◽  
Silver Bromide ◽  
Silver Halides ◽  
Ternary Reciprocal System ◽  
Fused Salts ◽  
Miscibility Gaps ◽  
Sodium And Potassium

Abstract The two families of systems formed by silver halides with alkali Chromates and tungstates have been systematically investigated in order to bring into evidence possible demixing phenomena. It has been found that silver chloride demixes with lithium Chromate and tungstate and with sodium tungstate; silver bromide demixes with lithium and sodium Chromates and tungstates; silver iodide demixes with lithium, sodium and potassium Chromates and tungstates. Moreover the whole compo-sition square of the ternary reciprocal system Ag, Na/Cl, WO4 has been investigated.The tendency to demix in these systems has been discussed on the basis of the characteristics of the ions.

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.

UV-VIS Absorption Spectra of Molten AgCl and AgBr and of their Mixtures with Group I and II Halide Salts

2015 ◽  
Vol 70 (10) ◽  
pp. 787-790
Author(s):  
Giorgio G.W. Greening
Keyword(s):  
Absorption Spectra ◽  
Absorption Edge ◽  
Silver Chloride ◽  
Silver Halide ◽  
Fundamental Absorption Edge ◽  
Silver Bromide ◽  
Group I ◽  
Halide Salts

AbstractThe UV-VIS absorption spectra of (Ag1-X[Li-Cs, Ba]X)Cl and of (Ag1-X[Na, K, Cs]X)Br at 823 K at the concentrations X=0.0, 0.1, 0.2 have been measured. The findings show that on adding the respective halides to molten silver chloride and silver bromide, shifts of the fundamental absorption edge to shorter wavelengths result. A correlation between the observed shifts and the expansion of the silver sub-lattice is found, which is valid for both silver halide systems studied in this work.

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.

Miscibility Gaps in Fused Salts

1968 ◽  
Vol 23 (12) ◽  
pp. 2073-2076
Author(s):  
Cesare Sinistri ◽  
Giorgio Flor ◽  
Paolo Ferloni
Keyword(s):  
Silver Iodide ◽  
Silver Chloride ◽  
Reciprocal System ◽  
Alkali Cation ◽  
Silver Bromide ◽  
Ternary Reciprocal System ◽  
Fused Salts ◽  
Miscibility Gaps

Molten mixtures of AgCl, AgBr and AgI with alkali molibdates have been investigated. The silver chloride presents stratification phenomena only with Li2MoO4, the silver bromide demixes with Li2MoO4 and Na2MoO4 while the silver iodide demixes with Li2MoO4, Na2MoO4 and K2MoO4. The ability of demixing, for mixtures containing the same halide, increases as the radius of the alkali cation diminishes (or the polarizing power of the same increases).Moreover the whole composition square of the ternary reciprocal system Ag, Na/Br, MoO4 has been investigated.

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