Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility

In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co–Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10(−6) cm(3)·g(−1)–1.29 × 10(−6) cm(3)·g(−1) for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti–6Al–4V, ~3.5 × 10(−6) cm(3)·g(−1), CP Ti and Ti–6Al–7Nb, ~3.0 × 10(−6) cm(3)·g(−1)), and one-sixth that of Co–Cr alloys (Co–Cr–Mo, ~7.7 × 10(−6) cm(3)·g(−1)). Among the Zr–Ru alloy series, Zr–1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr–Ru alloy system as therapeutic devices under MRI diagnostics environments.