Home  About us  Contact
 

Phosphate Phase (phosphate + phase)

Distribution by Scientific Domains
Polymers and Materials Science80%

Selected Abstracts

Microstructural Study of Mn and Si Co-substituted Hydroxyapatite Thin Films Produced by a Sol,Gel Method

ADVANCED ENGINEERING MATERIALS, Issue 7 2009
Aligül Büyükaksoy
Microstructural changes in sol,gel derived hydroxyapatite thin films associated with Mn and Si co-substitution are investigated. The apatite-forming ability of fabricated thin films in simulated body fluid are found to be affected by changes in the crystallinity and formation of a more dissolvable calcium phosphate phase. [source]

Biodegradation and Cytocompatibility Studies of a Triphasic Ceramic-Coated Porous Hydroxyapatite for Bone Substitute Applications

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2008
Annie John
Bone defects due to trauma or disease have led to the need for biomaterials as substitutes for tissue regeneration and repair. Herein, we introduce a porous triphasic ceramic-coated hydroxyapatite scaffold (HASi) for such applications. Interestingly, in the degradation experiments with isotonic buffer, HASi showed a significant release of silica with the disappearance of the tricalcium phosphate phase. Furthermore, the material also exhibited cytocompatibility with cultured bone marrow-derived mesenchymal stem cells of human origin. The material chemistry, together with the favorable cellular characteristics, indicates HASi as a promising candidate for critical-size bony defects, which still remains a formidable clinical challenge in the orthopedic scenario. [source]

Conversion of Tetranary Borate Glasses to Phosphate Compounds in Aqueous Phosphate Solution

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008
Wenhai Huang
In our earlier work, it was found that particles of a ternary alkali-borate glass, containing either CaO or BaO, converted completely to a crystalline phosphate of calcium or barium when reacted in an aqueous phosphate solution at 37°C. The present work is an extension of our earlier work to investigate the conversion of tetranary borate glass with the composition 10Li2O·10CaO·10(AeO or T2O3)·60B2O3 (weight percent), where Ae is the alkai-earth metal Mg or Ba, and T is the transition metal La, Sm, or Dy. In the experiments, particles of each glass (150,300 ,m) were reacted in 0.25M K2HPO4 solution with a starting pH of ,9.0 at 37°C. Weight loss and pH measurements indicated that the reaction was complete after 30,50 h, yielding an amorphous product. X-ray fluorescence showed that the as-formed product consisted of a calcium phosphate phase that contained the alkali-earth metal or transition metal present in the starting glass. Heating the as-formed material for 8 h at 600°,700°C produced a mixture of two crystalline phosphates: calcium phosphate and an alkali-earth or transition metal phosphate. The kinetics and mechanism of converting tetranary borate glass to phosphate materials are discussed and compared with data from earlier work for the conversion of ternary borate glass. [source]

Effect of Motif-Programmed Artificial Proteins on the Calcium Uptake in a Synthetic Hydrogel

MACROMOLECULAR BIOSCIENCE, Issue 10 2009
Traian V. Chirila
Abstract Motif-programmed artificial proteins with mineralization-related activity were covalently immobilized onto the surface of a hydrogel, poly(2-hydroxyethyl methacrylate) (PHEMA). We investigated the influence of assaying conditions upon the ability of three selected proteins (PS64, PS382 and PS458) to modulate calcification in vitro. A long-term assay measuring the real amount of calcium phosphate phase in the protein-modified PHEMA showed that all proteins enhanced the uptake of calcium by the hydrogel. For PS382 and PS458, this is a behaviour opposite to that displayed when the same proteins were tested in a free state by a rapid solution assay. Such difference may be attributed to a restricted mobility of the proteins due to immobilization. [source]

Application of a PEG/salt aqueous two-phase partition system for the recovery of monoclonal antibodies from unclarified transgenic tobacco extract

BIOTECHNOLOGY JOURNAL, Issue 9 2009
Dimitris Platis
Abstract Aqueous two-phase partition systems (ATPS) have been widely used for the separation of a large variety of biomolecules. In the present report, the application of a polyethylene glycol/phosphate (PEG/phosphate) ATPS for the separation of anti-HIV monoclonal antibodies 2G12 (mAb 2G12) and 4E10 (mAb 4E10) from unclarified transgenic tobacco crude extract was investigated. Optimal conditions that favor opposite phase partitioning of plant debris/mAb as well as high recovery and purification were found to be 13.1% w/w (PEG 1500), 12.5% w/w (phosphate) at pH 5 with a phase ratio of 1.3 and 8.25% w/w unclarified tobacco extract load. Under these conditions, mAb 2G12 and mAb 4E10 were partitioned at the bottom phosphate phase with 85 and 84% yield and 2.4- and 2.1-fold purification, respectively. The proposed ATPS was successfully integrated in an affinity-based purification protocol, using Protein A, yielding antibodies of high purity and yield. In this study, ATPS was shown to be suitable for initial protein recovery and partial purification of mAb from unclarified transgenic tobacco crude extract. [source]