High−toughness Zn-Mn-Ca alloys as potential materials for intestinal implants

Abstract

There have been many studies on the perspective Zn alloys for bone implants, but few for intestinal applications. Zn-0.4Mn-xCa (x = 0, 0.05 and 0.1 wt.%) alloys are developed in this work for intestinal applications, in order to make use of proliferation effects of Mn and Ca elements on intestinal probiotics and epithelial cells. Rat small intestinal crypt epithelial (IEC-6) cells can grow healthily on surfaces of all the alloys. Among them, the number of healthy cells on Zn-0.4Mn-0.1Ca is the largest. IEC-6 cell viability is over 160% (much higher than the benchmark of 75%) in 20%–100% extracts of Zn-0.4Mn-0.1Ca for 5 d. All the alloys can promote proliferation of Lactobacillus acidophilus (intestinal probiotic) and inhibit growth of Escherichia coli (intestinal pathogen). Among them, Zn-0.4Mn-0.1Ca alloy possesses the greatest effect. With the increase of Ca content, the strength of the alloy increases. Zn-0.4Mn-0.1Ca alloy has the highest strength and good plasticity among the three alloys. It exhibits a yield strength of 252 MPa, an ultimate tensile strength of 288 MPa, and a elongation to failure of 41%. Since CaZn₁₃-MnZn₁₃-Zn micro-cell controls corrosion rate, Zn-0.4Mn-0.1Ca with the highest volume fractions of MnZn₁₃ and CaZn₁₃ has the highest corrosion rate of 17.64 μm/year when immersed in simulated intestinal fluid for 28 d. Overall, the Zn-Mn-Ca alloys are promising candidates for intestinal implants.