Fluoroapatite glass-ceramic coating on alumina: surface behavior with biological fluids

The results of a surface analysis performed on a fluoroapatite-based glass ceramic (SAF) also coating a full-density α-alumina substrate (SAF-alumina coating) are presented. These two materials have also been evaluated after soaking in simulated body fluid to understand their ability to induce hydroxyapatite growth on them. Aiming to understand the fluoroapatite glass-ceramic interaction with some plasma proteins, in the second part of this study, fibronectin, albumin, immunoglobulin G, IgA, and complement factor C3c SAF binding have been evaluated; surface activity on complement activation has also been quantified. SAF-alumina coating provides good sites for the nucleation and growth of an apatite layer, equivalent to the mineral component of bone and binds preferentially plasma fibronectin, which is well known to enhance cell adhesion and spreading. Moreover, SAF-alumina coating reduces alumina complement activation directly or via reduced IgA binding. Alumina was shown to bind the same C3 fragments as Zymosan, used as complement activating control, and to induce increased levels of serum soluble iC3b and Bb. A mechanical resistant material with enhanced bioactivity, bone integration, and reduced inflammatory potential respect to alumina has been obtained.