Tóm tắt

The bioactivity assay originally proposed by Kokubo is one of the most commonly used tests to indirectlyrnevaluate the biocompatibility of bioactive glasses. However, extensive evidence has shown that trace elementsrnpresent in biomaterials may stimulate cellular behavior in different ways even when no apatite formation isrnobserved, i.e., in biomaterials with low or no bioactivity. To further elucidate this topic, we designed threerndifferent SiO2-rich bioglass compositions in which CaO was partially replaced by ZnO and MgO, two oxidesrnknown to affect bioactivity as well as osteoblastic behavior. The physicochemical changes induced by the pre-sence of oxides and their effects on biological behavior, as well as the adhesion, proliferation and differentiationrnof human osteoblast-like osteosarcoma cells (MG-63), were followed by a bioactivity assay in simulated bodyrnfluid (SBF). The insertion of ZnO or MgO decreased the glass transition (Tg) and crystallization (Tc) temperaturesrnas a function of the increase in nonbonding oxygens, which was directly reflected in the higher solubility. Thernrelease of Mgrn2+rnions from the MgO-containing samples inhibited the bioactivity in SBF, inducing high cellrnadhesion and proliferation and moderate ALP activity. The release of Znrn2+rnalso inhibited the bioactivity in SBFrnbut, in contrast to the release of Mgrn2+rn, induced low cell adhesion and proliferation and high ALP activityrncompared to the control.