Sintering, crystallisation and biodegradation behaviour of Bioglass®-derived glass–ceramics

TLDR

Sintering and crystallisation of 45S5 Bioglass® powders were studied to better understand the fabrication of Bioglass® glass‑ceramic scaffolds for tissue engineering. The authors used in‑situ environmental SEM with heating to monitor particle morphology during sintering and crystallisation, and performed SEM, TEM, XRD and EDX on samples in simulated body fluid to evaluate biodegradation and bioreactivity. The study identified optimal foam‑replica processing parameters, showed that SBF interaction involves preferential dissolution at glass/crystal interfaces, defect‑driven crystal breakdown, and amorphisation via ion‑exchange defects, and provides the first comprehensive assessment of processing, microstructure, and in‑vitro performance of Bioglass® glass‑ceramic scaffolds for bone tissue engineering.

Abstract

Sintering and crystallisation phenomena in powders of a typical bioactive glass composition (45S5 Bioglass®) have been investigated in order to gain further understanding of the processes involved in the fabrication of Bioglass® based glass–ceramic scaffolds for tissue engineering applications. In situ experiments in an environmental scanning electron microscope with a heating stage were carried out to follow the morphology of Bioglass® particles during sintering and crystallisation. Optimal processing parameters for the manufacture of Bioglass® based glass–ceramic scaffolds by the foam-replica technique were determined. To assess the in vitro performance and bioreactivity of Bioglass®-derived glass–ceramic scaffolds, the biodegradation of samples in simulated body fluid (SBF) was investigated using various techniques, including SEM, TEM, XRD and EDX. The mechanism of interaction of the glass–ceramic surface with SBF was determined, which involves (i) preferential dissolution at glass/crystal interfaces, (ii) break-down of crystalline particles into very fine grains through preferential dissolution at crystal structural defects, and (iii) amorphisation of the crystalline structure by introduction of point defects produced during ion exchange. The present report thus offers for the first time a complete assessment of the processing parameters, microstructure, and in vitro performance of Bioglass® derived glass–ceramic scaffolds intended for bone tissue engineering.