Effect of S53P4 bioactive glass content on structural and in-vitro behavior of hydroxyapatite/bioactive glass mixtures prepared by mechanical milling

This work presents silicon-substituted hydroxyapatite preparation through planetary ball milling using biogenic hydroxyapatite and different wt% of S53P4 bioactive glass (5, 10, 15, and 20 wt%) sources for the first time. The prepared mixtures showed a BHAp lattice contraction with SiO44− incorporation; rich- and poor-Si phases were subsequently identified. Furthermore, two types of interaction among the functional groups in the S53P4 and BHAp mixtures are proposed. First, the 95-5 (wt.%) sample displayed a BHAp lattice with SiO44−, CO32−, and OH− ions substitution. In samples with S53P4 BG content higher than 95-5, the lattice substitution was related to SiO44−, PO43−, and CO32− ions, and a dehydroxylation process occurred in the BHAp. Finally, the bioactive behavior of the samples was studied by immersion in Hank's solution for 7, 14, and 28 days. The results showed that the mixtures formed a bone-like apatite layer with a dune-like morphology that increased in size and quantity with increasing S53P4 content in the mixtures.