A bifunctional bone scaffold combines osteogenesis and antibacterial activity via in situ grown hydroxyapatite and silver nanoparticles

Abstract

Hydroxyapatite (HA) nanoparticles and silver (Ag) nanoparticles are expected to enable desirable bioactivity and antibacterial properties on biopolymer scaffolds. Nevertheless, interfacial adhesion between HA/Ag and the biopolymer is poor due to the large physicochemical differences between these components. In this study, poly L-lactic acid (PLLA) powder was first surface-modified with bioactive polydopamine (PDA) in an alkaline environment. Next, HA and Ag nanoparticles were grown in situ on the PDA-coated PLLA powder, which was then adhered to the porous bone scaffold using a selective laser-sintering process. Results showed that HA and Ag nanoparticles were homogenously distributed in the matrix, with enhanced mechanical properties. Simulated body fluid bioactivity tests showed that the in situ grown HA-endowed scaffold shows excellent bioactivity. In vitro tests confirmed that the scaffold exhibits favorable biocompatibility with human umbilical cord mesenchymal stem cells, as well as strong antibacterial activity against Gram-negative Escherichia coli. Furthermore, in vivo assays indicated that the scaffold promoted bone generation, with a new bone area fraction of 71.8% after 8 weeks’ implantation, without inflammation.