Enhanced antibacterial activity and osteoinductivity of Ag-loaded strontium hydroxyapatite/chitosan porous scaffolds...

The properties of bone scaffolds, including biocompatibility, osteoinductivity and antibacterial activity, are of great importance for reconstruction of large bone defects and prevention of implant-associated infections. Herein, we develop an Ag-loaded strontium hydroxyapatite (SrHAP)/chitosan (CS) porous scaffold (Ag-SrHAP/CS) according to the following steps: (i) freeze-drying fabrication of a SrHAP/CS porous scaffold; and (ii) deposition of Ag nanoparticles on the above scaffold. In addition, HAP/CS and Ag-HAP/CS porous scaffolds are prepared under the same conditions without doping Sr element. All the HAP/CS, Ag-HAP/CS, SrHAP/CS and Ag-SrHAP/CS porous scaffolds provide a friendly environment for the adhesion, spreading and proliferation of human bone marrow mesenchymal stem cells (hBMSCs). The three-dimensional (3D) interconnected macropores with a pore size of 100-400 μm allow the spreading of hBMSCs throughout the whole scaffolds. Interestingly, the Sr ions and Ag ions released from the Ag-SrHAP/CS porous scaffolds significantly enhance their osteoinductivity and antibacterial activity, respectively. The Sr element in the SrHAP/CS and Ag-SrHAP/CS porous scaffolds increase the alkaline phosphatase (ALP) activity of hBMSCs, extracellular matrix (ECM) mineralization, and the expression levels of osteogenic-related genes BMP-2 and COL-I. Moreover, the Ag ions released from the Ag-HAP/CS and Ag-SrHAP/CS scaffolds can effectively inhibit the growth and attachment of Staphylococcus aureus (S. aureus, ATCC 25923). In conclusion, the Ag-SrHAP/CS porous scaffold possesses excellent biocompatibility, osteoinductivity and antibacterial activity, so it has great potential for application in bone tissue engineering to repair bone defects and avoid infections.