Dissolution, leaching, and Al2O3 enrichment at the surface of bioactive glasses studied by solution analysis.
Five glass compositions in or near the bioactive region in the system SiO2-Na2O-CaO-P2O5-Al2O3-B2O3 were studied in vitro by immersion in Tris buffer. The Si concentration can be taken as a measure of the amount of dissolved glass, whereas the Na concentration can be used to estimate the thickness of the Si-rich (Si gel) layer. Upon immersing a bioactive glass into Tris buffer, a surface layer of a few micrometer thickness is dissolved during the first 8 h. During the first few hours of immersion, the rate of dissolution of the glass network is equal to or exceeds that of the growth of the Si-rich layer. If the glass contains Al2O3, most of the aluminum that would be released due to dissolution of the silica network is enriched in the Si-rich surface layer that forms due to leaching. Al2O3 is not only bonded by the Si gel but also interferes with formation of calcium phosphate.
Andersson
O H
OH
Department of Chemical Engineering, Abo Akademi University, Turku, Finland.
Rosenqvist
J
J
Karlsson
K H
KH
D000537:Aluminum Oxide / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D012825:Silicon / Q000032:analysis*; D012964:Sodium / Q000032:analysis*; D012995:Solubility; D014325:Tromethamine
D014325:Tromethamine; D012964:Sodium; D000537:Aluminum Oxide; D012825:Silicon