Unravelling the dissolution mechanism of polyphosphate glasses by ³¹P NMR spectroscopy: ligand competition and reactivity of intermediate complexes

Abstract

Phosphate glass dissolution can be tailored via compositional and subsequent structural changes, which is of interest for biomedical applications such as therapeutic ion delivery. Here, solid-state 31P nuclear magnetic resonance...

Ion Release Behavior of Silicophosphate Glasses Containing Six-Fold Coordinated Silicon Structure

“…Figure 2 shows the 29 Si MAS-NMR spectra of the glasses. Peaks at approximately -120 ppm and -215 ppm were observed for both the glasses and are assigned to 4-fold and 6-fold coordinated silicon structures (denoted by [4] Si and [6] Si, respectively), respectively. 8,9 The peak intensity of [6] Si in P50 was stronger than that in P45.…”

“…The MAS-NMR spectra showed that P45 was based on a Q P 2 structure with a large amount of [4] Si, while P50 was based on a Q P 3 structure with a large amount of [6] Si. Yamashita et al explained the [6] Si formation in terms of the electron donicity of oxygen (optical basicity).…”

“…1,2 Several studies on the compositional dependence of the glass on its solubility have been reported. 3,4 Döhler et al reported that when the P 2 O 5 content was increased from 35 to 50 mol%, while fixing the CaO/Na 2 O ratio in P 2 O 5 -CaO-Na 2 O glasses at unity, their ion-releasing rates increased. 5 Therapeutic ions, such as phosphate and silicate ions, are known to genetically stimulate osteoblasts and improve the bone-forming ability.…”

Structure and dissolution of silicophosphate glass

“…P 2 O 5 –Na 2 O–CaO glass has been widely studied, especially its structure and chemical durability. 1,10–13 However, only a few attempts have been made to modulate its solubility by introducing [6] Si. Silicon plays an effective role in bone formation.…”

“…It has been reported that the amount of [6] Si formation in phosphate glass varies not only with P 2 O 5 content but also with the types of NWMs (alkali and/or alkaline earth ions). 7,9 In this study, we tried to form some [6] 1,[10][11][12][13] However, only a few attempts have been made to modulate its solubility by introducing [6] Si. Silicon plays an effective role in bone formation.…”