Electrolytic Deposition of Calcium Phosphates Films on Nitinol Stents

2012 ◽  
Vol 529-530 ◽  
pp. 243-246
Author(s):  
Daisuke Kondo ◽  
Tomohiko Yoshioka ◽  
Toshiyuki Ikoma ◽  
Kensuke Takamatsu ◽  
Kunihiro Ohta ◽  
...  
Keyword(s):  
Complex Shape ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Dicalcium Phosphate ◽  
Electrolytic Deposition ◽  
Deposition Rates ◽  
Monocalcium Phosphate ◽  
Nitinol Stents ◽  
Cathode Current

Calcium phosphates films were deposited onto pipes and stents of nitinol alloys by an electrolytic deposition (ELD) method. Monocalcium phosphate (Ca (H2PO4)2·H2O) solutions were used as the electrolyte, and electric depositions were carried out at the constant cathode current of 1.59 mA/cm2 at 65°C for 60 min. From the deposition on nitinol pipes, deposition rates were changed in 15 minutes and the precipitates were identified to be octacalcium phosphate (Ca8H2(PO4)6·5H2O) and dicalcium phosphate anhydrous (CaHPO4). The electrolytic depositions on the nitinol alloys were useful for the formation of calcium phosphates films on the complex shape of stents.

Electrochemical Hydroxyapatite Coatings on Nitinol Stents for the Reduction of Metal Ions Elution

2014 ◽  
Vol 1626 ◽  
Author(s):  
Daisuke Kondo ◽  
Tomohiko Yoshioka ◽  
Toshiyuki Ikoma ◽  
Kensuke Takamatsu ◽  
Kunihiro Ohta ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Metal Ions ◽  
Calcium Phosphates ◽  
Toxic Metal ◽  
Octacalcium Phosphate ◽  
Electrolytic Deposition ◽  
Nickel Ions ◽  
Nitinol Stent ◽  
Hydroxyapatite Coatings ◽  
Nitinol Stents

ABSTRACTNitinol was coated with biocompatible calcium phosphate materials by pulsed electrolytic deposition (ELD) to reduce toxic metal-ions elution. The pulse ELD for the stents was carried out with changing the current off-periods (toff) of the pulse wave. The pulse ELD suppressed the generation of H2 gas due to the electrolysis of water on a calcium phosphate layer and improved the adhesiveness of the coating layer on nitinol compared with a conventional DC-ELD. The coating layers were identified to be octacalcium phosphate (OCP) at lower toff, while they were transformed to dicalcium phosphate anhydraous (DCPA) with an increase of toff. The layers of OCP or DCPA on the nitinol surface were subjected to a NaOH treatment at 60°C for 3days to transform them into hydroxyapatite (HAp). From results of a metal-ions elution test, the deposited calcium phosphates suppressed nickel ions elution at one quarter compared with the bare nitinol stent. These results indicate that the pulse ELD of biocompatible calcium phosphate materials on the nitinol stent was one of the best techniques to create firmly attached coating on it and reduce toxic nickel ions elution.

Seeded Growth of Calcium Phosphates: Effect of Different Calcium Phosphate Seed Material

1976 ◽  
Vol 55 (4) ◽  
pp. 617-624 ◽  
Author(s):  
G.H. Nancollas ◽  
J.S. Wefel
Keyword(s):  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Seeded Growth ◽  
Seed Crystals ◽  
Phosphate Dihydrate ◽  
Supersaturated Solutions

The growth of calcium phosphates on seed materials, dicalcium PhosPhate dihydrate (DCPD), tricalcium phosphate (TCP), octacalcium phosphate (OCP), and hydroxyapatite (HAP) in stable supersaturated solutions has been studied under conditions of pH and concentration for which the predominant phases are 1, DCPD, and II, HAP. All seed crystals are good nucleators for DCPD in system I, but, aside from HAP itself, only OCP will readily induce growth under condition II.

Electrolytic deposition of amorphous and crystalline zinc–calcium phosphates

1998 ◽  
Vol 33 (12) ◽  
pp. 3059-3063 ◽  
Author(s):  
P. T Olesen ◽  
T Steenberg ◽  
E Christensen ◽  
N. J Bjerrum
Keyword(s):  
Calcium Phosphates ◽  
Electrolytic Deposition

A Comparative Study of Bioceramics In Vitro and In Vivo

2005 ◽  
Vol 284-286 ◽  
pp. 11-14 ◽  
Author(s):  
Yang Leng ◽  
Ren Long Xin ◽  
Ji Yong Chen
Keyword(s):  
Calcium Phosphates ◽  
Glass Ceramics ◽  
Octacalcium Phosphate ◽  
Rabbit Muscle ◽  
In Vivo Experiments ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Dental Applications

Bioactive calcium phosphate (Ca-P) formation in bioceramics surfaces in simulated body fluid (SBF) and in rabbit muscle sites was investigated. The examined bioceamics included most commonly used bioglass®, A-W glass-ceramics and calcium phosphates in orthopedic and dental applications. The Ca-P cyrstal structures were examined with single crystal diffraction patterns in transmission electron microscopy, which reduced possibility of misidentifying Ca-P phases. The experimental results show that capability of Ca-P formation considerably varied among bioceramics, particularly in vivo. Octacalcium phosphate (OCP) was revealed on the all types of bioceramics in vitro and in vivo experiments. This work leads us to rethink how to evaluate bioactivity of bioceramics and other orthopedic materials which exhibit capability of osteoconduction by forming direct bonding with bone.

scholarly journals SOME EFFECTS OF MOISTURE AND TEMPERATURE ON TRANSFORMATION OF MONOCALCIUM PHOSPHATE IN SOIL

1962 ◽  
Vol 42 (2) ◽  
pp. 229-239 ◽  
Author(s):  
W. C. Hinman ◽  
J. D. Beaton ◽  
D. W. L. Read
Keyword(s):  
Water Soluble ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Inorganic P ◽  
Monocalcium Phosphate ◽  
Liesegang Rings ◽  
Phosphate Dihydrate ◽  
The Mean ◽  
Surrounding Soil

Pre-weighed monocalcium phosphate pellets, containing about 15 milligrams of P, were placed in 200 grams of soil and stored for 2 weeks at four moisture tensions and three temperatures. Pellet residues were then removed and the amount of phosphorus remaining was determined. Small cores containing pellet residues and the surrounding soil contacted by fertilizer solution were removed for determination of water-soluble and total inorganic P. Phosphate phases present at the granule sites and the surrounding soil were identified by their optical properties.The mean amount of phosphorus remaining at the granule sites was 20.2 per cent. Although both moisture tension and temperature significantly affected the quantity of phosphorus retained, no consistent trend was apparent. Residues remaining at the site of application were found to be mixtures of anhydrous and dihydrated dicalcium phosphate, with the latter predominating. Moisture tension and temperature did not greatly alter the proportion of the two phases.Periodic precipitates or Liesegang rings of dicalcium phosphate were formed in the soil surrounding monocalcium phosphate pellets. Dicalcium phosphate dihydrate was the predominant phase. The proportion of dihydrated to anhydrous dicalcium phosphate increased as the temperature decreased and as the moisture tension increased.Water-soluble P increased significantly with increased moisture tension and was significantly greater at 5 °C. than at either 16 or 27 °C. The mean of all treatments was 5.6 per cent. Increased amounts of dicalcium phosphate dihydrate in the surrounding soil seemed to be responsible for the increase in water solubility.Between 89.5 and 99.2 per cent of the added phosphorus was recovered in the water and acid extracts of soil cores containing about 1.4 cm.3 of soil.

scholarly journals Physico-chemical properties of calcium phosphates

2012 ◽  
Vol 59 (1) ◽  
pp. 7-21 ◽  
Author(s):  
Vesna Babic-Ivancic ◽  
Maja Dutour-Sikiric
Keyword(s):  
Calcium Phosphates ◽  
Chemical Properties ◽  
Organic Matrix ◽  
Octacalcium Phosphate ◽  
Carbonate Apatite ◽  
Organic Additives ◽  
Biologically Relevant ◽  
Beta Tricalcium Phosphate ◽  
Physico Chemical

Calcium phosphates have important role in biological and pathological mineralization. While only one of calcium phosphates, carbonate apatite, represents the main mineral component of teeth and bones, octacalcium phosphate, calcium hydrogenphosphate dihydrate and beta-tricalcium phosphate occur in pathological deposits. From the stand-point of chemists, processes of biological and pathological mineralization could be considered as deposition of inorganic phase within organic matrix, i.e. formation of inorganic-organic composites. Although this approach is very simplified at first glance, it allows clarification of important issues related to biomineralization (e.g. what is the role of individual components of organic matrix in the emerging solid tissue), and design and preparation of new materials for hard tissue regeneration (e.g. process of transformation after implantation). The importance of investigation about calcium phosphates will be presented through the overview of basic physico-chemical reactions related to the formation and transformation of biologically relevant calcium phosphates and their interaction with various organic additives in the laboratory.

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