Momeni Arash, Filiaggi Mark Joseph
School of Biomedical Engineering, Dalhousie University , Halifax, Nova Scotia, Canada B3H 3J5.
Langmuir. 2014 May 13;30(18):5256-66. doi: 10.1021/la500474j. Epub 2014 Apr 30.
The effect of chelation of three alkaline earth metals (Ca, Sr, and Ba) by polyphosphates on the pH and viscosity of the solution is examined and correlated to the phosphate glass properties. Also, the impact of the polyphosphate average degree of polymerization (D(p)) as well as the type and amount of chelated divalent cation on the degradation rate of the chains is studied. Subsequently, the number of divalent cations required for polyphosphate chain agglomeration to form a coacervate, and the resulting composition of these coacervates, was investigated. A decrease in polyphosphate solution pH during chelation was routinely obtained, with a sudden shift in the rate of pH drop occurring around a divalent cation/phosphorus molar ratio of 0.18. Longer chains or cations with a smaller ionic radius accelerated the rate of D(p) reduction. The number of divalent cations required for coacervation depends on different variables such as the polyphosphate concentration, the D(p), and the type of divalent cation. The formed coacervate retains the D(p) of polyphosphate originally used for coacervation, and the resulting Ca/P molar ratio depends largely on the amount of calcium being used during coacervation. Overall, this article helps one to understand the coacervation of polyphosphates in order to exploit their potential as a biomaterial.
研究了多磷酸盐对三种碱土金属（钙、锶和钡）的螯合作用对溶液pH值和粘度的影响，并将其与磷酸盐玻璃性质相关联。此外，还研究了多磷酸盐平均聚合度（D(p)）以及螯合二价阳离子的类型和数量对链降解速率的影响。随后，研究了多磷酸盐链团聚形成凝聚层所需的二价阳离子数量以及这些凝聚层的最终组成。螯合过程中多磷酸盐溶液的pH值通常会降低，在二价阳离子/磷摩尔比约为0.18时，pH值下降速率会突然发生变化。较长的链或离子半径较小的阳离子会加速D(p)的降低速率。凝聚所需的二价阳离子数量取决于不同变量，如多磷酸盐浓度、D(p)和二价阳离子类型。形成的凝聚层保留了最初用于凝聚的多磷酸盐的D(p)，最终的钙/磷摩尔比在很大程度上取决于凝聚过程中使用的钙的量。总体而言，本文有助于人们理解多磷酸盐的凝聚作用，以便开发其作为生物材料的潜力。
