Structure, biomineralization and biodegradation of Ca-Mg oxyfluorosilicates synthesized by inorganic salt coprecipitation

TL;DR

This study synthesized Ca-Mg oxyfluorosilicates with varying fluoride levels, analyzing their structure, biomineralization potential, and biodegradability, revealing optimal fluoride doping for biomedical applications.

Contribution

It introduces a novel synthesis method for fluoride-doped Ca-Mg oxyfluorosilicates and identifies optimal fluoride levels for enhanced biomineralization.

Findings

Samples with up to 2 mol% F are single-phase diopside.

Optimal fluoride content for biomineralization is 1 mol%.

Fluoride incorporation enhances apatite formation without forming fluorite.

Abstract

In this research, a novel group of Ca-Mg oxyfluorosilicates containing different levels of fluoride substituting for oxide was synthesized by an inorganic salt coprecipitation process followed by calcination/sintering. The effects of the incorporation of fluoride on the resultant structural characteristics, apatite-forming ability and biodegradability were evaluated by X-ray diffraction, transmission electron microscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, inductively coupled plasma spectroscopy and pH measurements. According to the results, the samples containing up to 2 mol% F present a single-phase structure of diopside (MgCaSi2O6) doped with F. It was also found that to meet the most biomineralization characteristic, the optimal value of fluoride in the homogeneous samples is 1 mol%. In this regard, on the one hand, the partial incorporation of fluoride into apatite (via forming fluorohydroxyapatite) and, on the other hand, the absence of fluorite (CaF2) as a consumer of Ca in the deposits are responsible for achieving the most apatite-forming ability circumstance controlled by an ion-exchange reaction mechanism. In conclusion, this study reflects the merit of the optimization of fluoride-doping into Ca-Mg silicates for development in biomedicine.