Nanostructural Transitions in Bioactive Sol-Gel Silicate Glasses

Abstract

A study of the short‐range organization of bioactive SiO2–P2O5–CaO sol–gel glasses using high‐resolution transmission electron microscopy, Fourier transform infrared and magic angle spinning—nuclear magnetic resonance spectroscopies are reported. These combined techniques were used to investigate the rearrangement of the glass matrix and to clarify the role of phosphorus and calcium during the heat‐treatment stage of the sol–gel process. The study shows how the incorporation of calcium into the glass structure promotes the appearence of P–O–NBO groups and that the glass nanostructure is induced to form Ca‐rich orthophosphate units.

A New Quantitative Method to Predict the Bioactive Behavior of Silicate Glasses

“…This confirms the association of this structural unit to the hydroxyl group. Moreover, this finding is ratified by the absence of the Si–O–2NBO vibration in the Raman spectra of sol‐gel glasses (see Refs and ). Furthermore, the notable presence of the group in the glass matrix of 25 and 33 FS samples suggests the predominance in these glasses' networks of short chains, such as trimers and even dimers.…”

“…In our previous studies, we set out a comprehensive review of the assignment of the optical vibration modes associated with different functional groups of both melting and sol-gel bioactive glasses. 8,44,46 Also, from MAS-NMR analysis, the bonding structure of P and Si atoms was elucidated and the presence of phosphorus in an isolated crystal-like environment was confirmed using HRTEM analysis. 29,[47][48][49][50][51][52][53] Despite the progress made, the question of a global method to predict the bioactive response of the glass, irrespective of the synthesis process is still open.…”

“…In our previous studies, we set out a comprehensive review of the assignment of the optical vibration modes associated with different functional groups of both melting and sol‐gel bioactive glasses . Also, from MAS‐NMR analysis, the bonding structure of P and Si atoms was elucidated and the presence of phosphorus in an isolated crystal‐like environment was confirmed using HRTEM analysis …”

Role of the Short Distance Order in Glass Reactivity

“…They suggested that the phosphate nanoregions may act as nucleation sites for the calcium phosphate-rich layer. Later on, this group investigated the nanostructure of SiO 2 –P 2 O 5 –CaO S-GG [23]. The study showed how the incorporation of calcium into the glass promoted the appearance of P–O Nonbonding Oxygen (NBO) groups and that the glass nanostructure was induced to form Ca-rich orthophosphate units.…”

Effect of Particle Size on the Electrophoretic Deposition of Hydroxyapatite Coatings: A Kinetic Study Based on a Statistical Analysis

“…Electrophoretic deposition (EPD) is successfully implemented for the fabrication of dense and uniform HA coatings on the substrates with various geometries . Moreover, EPD is more economically favorable technique among other methods such as plasma spray, sputtering, sol‐gel, and biomimetic . The basis of an EPD process is the migration of colloidal particles suspended in a liquid medium under the influence of an electric field (electrophoresis) and their deposition on an electrode …”