In vitro and in vivo degradation of Mg-Nd-Zn-Zr alloy

doi:10.3969/j.issn.2095-4344.2013.47.008

Abstract

Abstract:

BACKGROUND: Alloying is a convenient and effective method to alter the microstructure and control the corrosion behavior of magnesium alloy.
OBJECTIVE: To explore the in vitro and in vivo degradation of Mg-Nd-Zn-Zr alloy as a degradable medical biomaterial.
METHODS: (1) In vitro static immersion test: The immersion tests were carried out at (37.0±0.5) ℃ in a thermostatic bath. Six Mg-Nd-Zn-Zr alloy samples and six pure magnesium samples were immersed in the 250 mL simulated body fluid and vibrated without agitation during immersion. After 3, 7 and 30 days static immersion, the samples were taken out from the simulated body fluid. Then the in vitro corrosion properties were evaluated using scanning electron microscope and energy dispersive spectrometer analysis. (2) In vivo animal experiment: After bone tunnel was established in the left femur of adult New Zealand rabbits, the Mg-Nd-Zn-Zr alloy rods were embedded in the Mg-Nd-Zn-Zr alloy group, titanium alloy rods were embedded in the titanium alloy group, and only bone tunnel was established in the sham-operated group. At 1, 2, 4, 8 weeks after implantation, an X-ray of the implanted region was taken to determine the location and the degradation behavior of Mg-Nd-Zn-Zr alloy. At 4, 8 weeks after implantation, the corrosion product and its element composition were observed using scanning electron microscope with an energy dispersive spectroscopy system.
RESULTS AND CONCLUSION: (1) The static immersion test showed that Mg-Nd-Zn-Zr alloy degraded slower than pure magnesium at each time point. It was obvious that there was a corrosion layer on the surface of Mg-Nd-Zn-Zr alloy after 30 days immersion in the simulated body fluid. Energy dispersive spectroscopy analysis revealed that these particles were mainly composed of oxygen, carbon, sodium, magnesium, calcium, phosphate and chlorine. After the corrosion products were removed, corrosion pits could be clearly seen on the surface of Mg-Nd-Zn-Zr alloy and pure magnesium. However, the corrosion pits on the surface of Mg-Nd-Zn-Zr alloy were smaller and more even than those on the surface of pure magnesium. This shows that the degradation modes of the Mg-Nd-Zn-Zr alloy and pure magnesium are distinctly different. (2) After implanted into the animals, the Mg-Nd-Zn-Zr alloy gradually degraded with time. And the corrosion products and ingredients were similar to the in vitro results.

Key words: alloys, biocompatible materials, biodegradation, environmental

CLC Number:

R318

Wang Yong-ping, Jiang Yao, Mao Lin, Niu Jia-lin, Yuan Guang-yin. In vitro and in vivo degradation of Mg-Nd-Zn-Zr alloy[J]. Chinese Journal of Tissue Engineering Research, 2013, 17(47): 8189-8195.

Figures/Tables 5

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