Antibacterial and Biological Properties of a Micro-structured BMP-2/Chitosan/Hydroxyapatite Hybrid Coating on Ti Surface

Abstract

In this paper, the micro-structured hydroxyapatite (HA)/TiO₂ coating was firstly produced on titanium surface by one-step micro-arc oxidation (MAO), and then bone morphogenic protein-2 (BMP-2)-encapsulated chitosan (CS) coating was prepared on the HA/TiO₂ surface by dip-coating method to endow the bioactive HA/TiO₂ coating with good antibacterial property and improved biological properties. The bonding strength between coatings was studied by scratch method. The degradability of CS, BMP-2 release behavior, bioactivity, biocompatibility and antibacterial property of the BMP-2/CS/HA/TiO₂ composite coating were examined by in vitro tests. The results showed that, after loading BMP-2/CS on HA/TiO₂ surface, the surface roughness and wettability decreased but the bonding strength between the HA coating and titanium substrate was improved. CS, as a suitable carrier for sustained release of BMP-2, can control the release of BMP-2 continuously for 4 weeks long in a simulated human serum, and in PBS solution BMP-2 can be released more slowly. In addition, CS endowed the BMP-2/CS/HA/TiO₂ composite coating with good antibacterial activity. The BMP-2/CS/HA/TiO₂ showed good bioactivity, and it was also beneficial for cell adhesion, spreading and proliferation. Based on the above results, BMP-2/CS/HA/TiO₂ has great potential to be applied in clinic.