Metal-phenolic networks as a promising platform for pH-controlled release of bioactive divalent metal ions

Abstract

Titanium (Ti)-based implants have to undergo many severe ordeals under the complex in vivo microenvironments, which makes greater demands on the biological function of their surfaces. As a result, it is particularly important to develop the intelligent surfaces of Ti-based implants. In this study, metal-phenolic networks (MPNs) were prepared on pure Ti surfaces to achieve the pH-controlled release of bioactive divalent metal ions (e.g., Sr2+, Cu2+, Zn2+, and Mn2+). The practical potential of MPNs-based coatings in biomedical applications was further highlighted by the controllable release amount and species of metal ions. MPNs coated Ti surfaces displayed excellent biological properties, including enhanced protein adsorption, good biocompatibility as well as the promoted adhesion and proliferation of mesenchymal stem cells (MSCs). What’s more, a continuous release of bioactive divalent metal ions (e.g., Sr2+ and/or Cu2+) significantly accelerated the osteogenic differentiation of MSCs. The surface modification method based on MPNs provides an extremely feasible solution for preparing Ti-based implants that can adapt to different in vivo microenvironments.