Functionalized surface of a ceramic carbonated apatite substrate with an antibacterial α-tocopheryl phosphate organic layer

Carbonated apatite (CA) is a bioresorbable calcium phosphate ceramic widely regarded as the closest synthetic analog to the mineral phase of biological bone. Due to this close chemical similarity, CA is an attractive candidate for the treatment of skeletal defects. In parallel, the promising bioactive molecule α-tocopheryl phosphate (α-TP), a phosphorylated derivative of vitamin E, has recently gained significant attention due to its reported antibacterial potential and favorable interactions with biomaterial surfaces. Here, we investigate the feasibility of developing a hybrid material consisting of a ceramic CA substrate coated with a functional α-TP organic layer. The aim is to determine whether α-TP can be deposited and retained on the CA ceramic surface in a controllable and measurable manner, while preserving the key characteristics of the substrate. Particular attention is given to the chemical features of the modified surface, as well as changes in topographical and mechanical behavior following the functionalization. The central hypothesis of this study is that the calcium-phosphate rich surface of CA can suitably support α-TP immobilization without compromising the intrinsic properties that make CA a clinically relevant bone substitute. Establishing this interface would provide the basis for a monolithic hybrid grafting material that combines the bioresorbable and osteoconductive character of CA with the added antibacterial functionality from a bioactive surface layer imparted by α-TP. This work, therefore, represents an initial step toward the development of advanced bioresorbable synthetic bone grafts with enhanced surface-driven biological performance.