Study on degradation tracer and osteogenic ability of CS / NaYF4: Yb3+, Er3+ / AZ31 composites

Abstract In order to reduce the degradation rate of magnesium alloys and improve their biocompatibility, polymers are often used to modify their surfaces. However, there is a lack of non-invasive means to detect degradation of polymer coatings, and tracking composite degradation is important for various of applications such as tissue engineering and drug delivery. Among various imaging tools, upconversion nanoparticles emitting visible light under near-infrared excitation hold promise in tracking post-implantation degradation of polymer composites. We therefore report a simple synthetic method to surface coat AZ31 magnesium alloy using chitosan and monitor its degradation by using the release of NaYF4: Yb3+, Er3+ encapsulated therein to cause a decrease in the fluorescence intensity of the coating. We found that the addition of the composite coating reduced the degradation rate of AZ31 magnesium alloy, improved its biocompatibility and verified its osteogenic ability, and that the fluorescence intensity of the composite coating had a linear relationship with the degradation time. Thus, in this study, the prepared AZ31-CN paved the way for non-invasive monitoring of the degradation behavior of the composite and could be the great candidate material for bone regeneration.