Development and characterization of silver containing calcium phosphate coatings on pure iron foam intended for bone scaffold applications

Abstract

Despite its high structural strength and degradability, the potentiality of pure iron foam for bone scaffolds is low due to its lack of surface bioactivity. This work aims to provide a surface bioactivity to the iron foam by developing a calcium phosphate (CaP) conversion coating. Silver (Ag), known for its antibacterial property, was then incorporated onto the CaP coating via co-deposition (Ag/CaP-c) and post-treatment (Ag/CaP-p). By tuning the Ca/P ion ratio and Ag concentration during the coating process, an optimum coating parameter was obtained. All coatings were found to enhance mineralization ability and mechanical integrity of the iron foam over time. Electrochemical and immersion tests indicated that the coatings regulated the degradation rate of the iron foam via a variation of coating resistance and capacitance. Silver ions were released slowly from the Ag/CaP coating during the immersion test indicating a potential long-term antibacterial property of the coating. Details on the coating design and process optimization, the effects of three different simulated physiological solutions, and the mechanical property of the coated iron foam are discussed in this report.