Cu and Si co-doped microporous TiO2 coating for osseointegration by the coordinated stimulus action

Abstract

Biocompatible implant materials with enhanced antibacterial activity, osteogenic and angiogenic capacity are beneficial to osseointegration. Based on the outstanding antimicrobial activity of copper (Cu) and bone-related element silicon (Si), the microporous TiO2 coatings (M-Ti) doped with Cu2+ (M-Cu) and different doses of Si2+ (M-CuSi) were directly fabricated via the simple one-step micro-arc oxidation (MAO). M-Cu causes obvious toxicity towards osteoblasts (OBs) and endothelial cells (ECs) while maintaining excellent antimicrobial activity. By doping Si, it is able to compensate the cytotoxicity of Cu and simultaneously further enhance the activity of OBs and ECs by the synergic stimulatory effects with Cu2+, thus forming a balance between the antibacterial property and biocompatibility. In vitro experiments indicated that the M-CuSi5 coating not only shows good antibacterial properties towards Staphylococcus aureus (S. aureus), but also promotes attachment, spreading, proliferation and differentiation of both OBs and ECs. The most suitable release amount of Cu2+ and Si2+ from M-CuSi5 coating can cause distinctly synergistic stimulatory effects on osteogenesis and angiogenesis by facilitating the osteogenic-related genes and angiogenic-related genes expression. In vivo Micro-CT evaluation and histological observations further mirror that the M-CuSi5 coating results in ameliorative osseointegration, thus being attractive candidate as the bone implant material.