Both implant centered infection and deficient osteoinduction are pivotal issues for orthopedic implants in early and long-term osseointegration, but constructing a functional bio-interface that can overcome these two problems is highly challenging. Our study reveals that the bio-interface with promoted positive charges plays an active role in simultaneously enhancing the antibacterial and osteoinductive capability of orthopedic implants. The positively-charged bio-interface is fabricated by a simple dipping method, in which the cationic polymer (polyhexamethylene biguanidine, PHMB) is immobilized in the conjugated polydopamine coating. Mediated by the cation-π interaction, the immobilized PHMB elevates the surface potential resulting in excellent antibacterial efficacy corresponding to 5 ppm of free PHMB. The materials exhibit far better cytocompatibility than free PHMB at the dose which kills over 50% of the cells. Most importantly, the cationic surface can function as a bioelectrical microenvironment to guide bone mesenchymal stem cells and consequently, enhanced cellular viability and proliferation together with upregulated osteogenesis are achieved. The cation-π interaction mediated cationic surface overcomes the disadvantages plaguing immobilized cationic antibacterial compounds prepared by other methods and is applicable to different types of biomedical materials requiring antibacterial and osteoinductive bio-interfaces. J. Mater. Chem. B, 2014 |
