Cold hydrostatic sintering of 45S5 bioactive glass

Fully amorphous 45S5 bioactive glass pellets were successfully consolidated at room temperature using cold hydrostatic sintering (CHS) and their acellular bioactivity was determined by immersion test in simulated body fluid (SBF). Crystalline 45S5 BG samples prepared using conventional sintering (TS) at 1050 °C were also tested. Preliminary results indicated the formation of hydroxyapatite (HAP) on the surfaces of both samples after immersion in SBF, which was confirmed using SEM, FTIR, and XRD analyses. The amount of hydroxyapatite increases by increasing the SBF immersion time. Results revealed that the amount of HAP crystalline phase was similar in both samples after 14 days of incubation in SBF (i.e., 23% in TS and 25% in CHS samples). The pellets prepared by TS resulted in a relative density of 95.6% and a hardness of about 3.5 GPa. On the other hand, CHS samples had a hardness of 1.2 GPa and a relative density of 75.1%, indicating the presence of a porous structure that can be beneficial for the interaction of the material with proteins and cells (both in vitro and in vivo).