Microstructure and biocompatibility of gold-lanthanum strips

Abstract

Microalloying of pure gold, which has the highest biocompatibility but relatively low yield strength and poor wear resistance, might improve its applicability as adornments and biomedical implants. The objective of this study was to analyse the microstructure and biocompatibility of gold-lanthanum (Au-0.5 wt% La) microstrips as a potential biomaterial in dentistry or medicine. We found that microalloying of Au with La produced very fine nanosized grains homogeneously dispersed through the entire volume of the rapidly solidified (RS) alloys. This initiates the formation of Au6La phase which increases strength and hardness of the alloy significantly. By RS, large reduction of grains and microsegregation increases the strength of the alloy additionally. Our results suggest that Au-La microstrips, although non-cytotoxic for L929 cells, rat thymocytes, rat peritoneal macrophages (PMØ) and human peripheral blood mononuclear cells (PBMNCs), can activate immune cells. Namely, RS Au-La microstrips stimulated the production of nitric oxide (NO) by PMØ. Using a model of phytohemaglutinine (PHA)-stimulated human PBMNCs, we found that RS Au-La strips increased the proliferation of these cells and stimulated the production of Th1, Th17 cytokines, and immunoregulatory cytokine IL-10. Our results suggest that RS Au-La microstrips are biocompatible, but they can modulate the immune response. Therefore, their use as potential implants should be considered carefully.