Indirectly extruded biodegradable Zn-0.05wt%Mg alloy with improved strength and ductility: In vitro and in vivo studies

doi:10.1016/j.jmst.2018.01.006

Abstract

Abstract:

As compared to permanent orthopedic implants for load-bearing applications, biodegradable orthopedic implants have the advantage of no need for removing after healing, but they suffer from the “trilemma” problem of compromising among sufficiently high mechanical properties, good biocompatibility and proper degradation rate conforming to the growth rate of new bones. In the present work, in vitro and in vivo studies of a Zn-0.05wt%Mg alloy (namely, Zn-0.05Mg alloy) were conducted with pure Zn as a control. The Zn-0.05Mg alloy is composed of a small amount of Mg₂Zn₁₁ phase embedded in the refined Zn matrix with an average grain size of ~20 μm. The addition of 0.05 wt% Mg into Zn significantly increases the ultimate tensile strength up to 225 MPa and the elongation to fracture to 26%, but has little influence on the in vitro degradation rate. Both Zn and Zn-0.05Mg alloy exhibit homogeneous in vitro degradation with a rate of about 0.15 mm/year. Based on the cytotoxicity evaluation, Zn and Zn-0.05Mg alloy do not induce toxicity to L-929 cells, indicating that they have little toxicity to the general functions of the animal. An in vivo biocompatibility study of Zn and Zn-0.05Mg alloy samples by placing them in a rabbit model for 4, 12 and 24 weeks, respectively did not show any inflammatory cells, and demonstrated that new bone tissue formed at the bone/implant interface, suggesting that Zn and Zn-0.05Mg alloy promote the formation of new bone tissue. The in vivo degradation of Zn and Zn-0.05Mg alloy does not bring harm to the important organs and their cell structures. More interestingly, Zn and Zn-0.05Mg alloy exhibit strong antibacterial activity against Escherichia coli and Staphylococcus aureus. The above results clearly demonstrate that the Zn-0.05Mg alloy could be a potential biodegradable orthopedic implant material.

Key words: Zn-Mg alloy, Mechanical properties, Biodegradability, Biocompatibility, Antibacterial activity

Chi Xiao, Liqing Wang, Yuping Ren, Shineng Sun, Erlin Zhang, Chongnan Yan, Qi Liu, Xiaogang Sun, Fenyong Shou, Jingzhu Duan, Huang Wang, Gaowu Qin. Indirectly extruded biodegradable Zn-0.05wt%Mg alloy with improved strength and ductility: In vitro and in vivo studies[J]. J. Mater. Sci. Technol., 2018, 34(9): 1618-1627.

Figures/Tables 7

Fig 1. Microstructures and tensile properties of the as-extruded alloys: (a) cross section of pure Zn; (b) longitude section of pure Zn; (c) cross section of Zn-0.05Mg; (d) longitude section of Zn-0.05Mg (inserts SEM-BSE morphologies of second phase in (c) and (d)); (e) tensile stress-strain curve of the as-extruded alloys; (f) tensile properities of the as-extruded alloys.

Fig. 2. In vitro degradation of as-extruded Zn amd Zn-0.05Mg in SBF: (a) potentiodynamic curves; (b) corrosion rates of the immersion tests. Surface morphology of (c) Zn and (d) Zn-0.05Mg after soaking for 14 days.

Fig. 3. L-929 cell morphology in 5 days incubation: (a) 10% extract of pure Zn; (b) 50% extract of pure Zn; (c) 100% extract of pure Zn; (d) 10% extract of Zn-0.05Mg; (e) 50% extract of Zn-0.05Mg; (f) 100% extract of Zn-0.05Mg; (g) negative control; (h) positive control. RGR of L-929 cells in 1, 3 and 5 days incubation in 10%, 50% and 100% extracts of (i) Zn and (j) Zn-0.05Mg. (There is statistical significance between the extraction groups and positive group (p < 0.05), but no statistical significance between the extraction groups and negative groups (p > 0.05).

Fig. 4. Representative histology of cross-sections of bone-implant interface stained with Toluidine blue and observed by microscopy: Zn for (a) 12 weeks, (b) 24 weeks; Zn-0.05Mg for (c) 12 weeks, (d) 24 weeks. In (a)-(d), there are normal cortical bones (blue arrow); implant (white arrow); newly formed bone fractions around the implant (red arrow); bone junction between cortical bone and new bone formation (green arrow). And element mapping analysis on a cross-section of bone/implant interface: Zn for (e) 12 weeks and (f) 24 weeks; Zn-0.05Mg for (g) 12 weeks and (h) 24 weeks. Concentration of Zn (blue area); concentration of C (green area), medullary cavity regions and surrounding tissue; concentration of Ca (red area). Implants with a high Zn concentration, the newly formed bone fractions around the implants showing enriched Ca.

Fig. 5. Blood biochemical indicators: (a) Albumin; (b) alkaline phosphatase; (c) ALT; (d) AST; and (e) CREA; (f) UREA; (g) serum magnesium; (h) serum zinc. The black dot lines in (a)-(h) represent the health reference ranges.

Fig. 6. Morphology of (a) E. coli and (b) S. aureus co-culture with Ti-6Al-4V, pure Zn and Zn-0.05Mg alloy at 37 °C for 24 h. Antibacterial rates of Ti-6Al-4V, pure Zn and Zn-0.05Mg alloy against (c) E. coli and (d) S. aureus.

Table 1 Basic mechanical properties of typical Zn- and Mg-based biomaterials and nature bone.

Material	TYS (MPa)	UTS (MPa)	Elongation (%)	Ref.
Bone		130-180	1-2	[25], [38]
As-cast Zn-1Mg	~90	~150	~1.7	[25]
Extruded Zn-0.8Mg	203	301	15	[26]
Extruded Zn-1.6Mg	~230	367	~4	[26]
Extruded Pure Zn	~35	~65	~3.7	[28]
Extruded Zn-1Mg	~205	~265	~8.5	[28]
Extruded Zn-1Ca	~200	~240	~7.8	[28]
Extruded Zn-1Sr	~220	~265	~10.8	[28]
Extruded Zn-1Mg-1Ca	~205	~260	~5.3	[29]
Extruded Zn-1Mg-1Sr	~200	~250	~7.3	[29]
Extruded Zn-1Ca-1Sr	~210	~260	~6.8	[29]
As-rolled Zn-1Mg-0.1Mn	195.02	299.04	26.07	[30]
Extruded Zn-1Mg	~180	~250	~12	[35]
Extruded Zn	51	111	60	[39]
Extruded Zn-0.15Mg	114	250	22	[39]
Extruded Zn-0.5Mg	159	297	13	[39]
Extruded Zn-1Mg	180	340	6	[39]
Extruded Zn-3Mg	291	399	1	[39]
Deformed HP Mg	148.5	199.1	8.1	[40]
Extruded Mg-6Zn	169.5	279.5	18.8	[7]
Extruded Mg-1Mn-2Zn	246	280	~20	[41]
WE43	216.67	297.67	21.67	[42]
Extruded Mg-1Ca	~130	239.63	10.63	[8]
Extruded Pure Zn	65	110	14	This work
Extruded Zn-0.05Mg	160	225	26	This work

References

[1]	M. Long, H.J. Rack, Biomaterials, 19(1998), pp. 1621-1639
[2]	H.J. Rack, J.I. Qazi, Mater. Sci. Eng. C, 26(2006), pp. 1269-1277
[3]	M. Niinomi, Metall. Mater. Trans. A, 33(2002), pp. 477-486
[4]	B. Basu, D. Katti, A. Kumar, Advanced Biomaterials Fundamentals, Processing and Applications, John Wiley & Sons Hoboken, New York (2009), pp. 12-45
[5]	H. Wang, Z.M. Shi, K. Yang, Adv. Mater. Res., 32(2008), pp. 207-210
[6]	C.K. Seal, K. Vince, M.A. Hodgson, Mater. Sci. Eng. Conf. Ser., 4(2009), p. 012011
[7]	S.X. Zhang, X.N. Zhang, C.L. Zhao, J.A. Li, Y. Song, C.Y. Xie, H.R. Tao, Y. Zhang, Y.H. He, Y. Jiang, Y.J. Bian, Acta Biomater., 6(2010), pp. 626-640
[8]	Z.J. Li, X.N. Gu, S.Q. Lou, Y.F. Zheng, Biomaterials, 29(2008), pp. 1329-1344
[9]	X.N. Gu, X.H. Xie, N. Li, Y.F. Zheng, L. Qin, Acta Biomater., 8(2012), pp. 2360-2374
[10]	H. Qin, Y.C. Zhao, Z.Q. An, M.Q. Cheng, Q. Wang, T. Cheng, Q.J. Wang, J.X. Wang, Y. Jiang, X.L. Zhang, G. Yuan, Biomaterials, 53(2015), pp. 211-220
[11]	L.P. Xu, G.N. Yu, E.L. Zhang, F. Pan, K. Yang, J. Biomed. Mater. Res. A, 83(2007), pp. 703-711
[12]	A.C. Hanzi, I. Gerber, M. Schinhammer, J.F. Loffler, P.J. Uggowitzer, Acta Biomater., 6(2010), pp. 1824-1833
[13]	S. Hiromoto, A. Yamamoto, Electrochim. Acta, 54(2009), pp. 7085-7093
[14]	F. Geng, L.L. Tan, X.X. Jin, J.Y. Yang, K. Yang, J. Mater. Sci.: Mater. Med., 20(2009), pp. 1149-1157
[15]	J. Hu, C. Wang, W.C. Ren, S. Zhang, F. Liu, Mater. Chem. Phys., 119(2010), pp. 294-298
[16]	H.X. Wang, S.K. Guan, X. Wang, C.X. Ren, L.G. Wang, Acta Biomater., 6(2010), pp. 1743-1748
[17]	X.N. Gu, W. Zheng, Y. Cheng, Y.F. Zheng, Acta Biomater., 5(2009), pp. 2790-2799
[18]	C. Lorenz, J.G. Brunner, P. Kollmannsberger, L. Jaafer, B. Fabry, S. Virtanen, Acta Biomater., 5(2009), pp. 2783-2789
[19]	D. Vojtìch, J. Kubásek, J. Capek, I. Pospísilová, Mater. Technol., 49(2015), pp. 877-882
[20]	S.F. Zhu, N. Huang, L. Xu, Y. Zhang, H.Q. Liu, H. Sun, Y.X. Leng, Mater. Sci. Eng. C, 29(2009), pp. 1589-1592
[21]	M. Peuster, P. Wohlsein, M. Brugmann, M. Ehlerding, K. Seidler, C. Fink, H. Brauer, A. Fischer, G. Hausdorf, Heart, 86(2001), pp. 563-569
[22]	M. Peuster, C. Hesse, T. Schloo, C. Fink, P. Heerbaum, C. von Schnakenburg, Biomaterials, 27(2006), pp. 4955-4962
[23]	M. Schinhammer, P. Steiger, F. Moszner, J. L?ffler, P. Uggowitzer, Mater. Sci. Eng. C, 33(2013), pp. 1882-1893
[24]	M. Schinhammer, A.C. Hanzi, J.F. Loffler, P.J. Uggowitzer, Acta Biomater., 6(2010), pp. 1705-1713
[25]	D. Vojtech, J. Kubasek, J. Serak, P. Novak, Acta Biomater., 7(2011), pp. 3515-3522
[26]	J. Kubasek, D. Vojtech, E. Jablonska, I. Pospisilova, J. Lipov, T. Ruml, Mater. Sci. Eng. C, 58(2016), pp. 24-35
[27]	P.K. Bowen, J. Drelich, J. Goldman, Adv. Mater., 25(2013), pp. 2577-2582
[28]	H.F. Li, H.X. Xie, Y.F. Zheng, Y. Cong, F.Y. Zhou, K.J. Qiu, X. Wang, S.H. Chen, L. Huang, L. Tian, L. Qin, Sci. Rep., 5 (10719) (2018), 10.1038/serp10719
[29]	H.F. Li, H.T. Yang, Y.F. Zheng, F.Y. Zhou, K.J. Qiu, X. Wang, Mater. Des., 83(2015), pp. 95-102
[30]	X.W. Liu, J.K. Sun, F.Y. Zhou, Y.H. Yang, R.C. Chang, K.J. Qiu, Z.J. Pu, L. Li, Y.F. Zheng, Mater. Des., 94(2016), pp. 95-104
[31]	X.W. Liu, J.K. Sun, Y.H. Yang, F.Y. Zhou, Z.J. Pu, L. Li, Y.F. Zheng, Mater. Lett., 165(2016), pp. 242-245
[32]	H. Tapiero, K.D. Tew, Biomed. Pharmacother., 57(2003), pp. 399-411
[33]	F. Witte, N. Hort, C. Vogt, S. Cohen, K.U. Kainer, R. Willumeit, F. Feyerabend, Curr. Opin. Solid State Mater. Sci., 12(2008), pp. 63-72
[34]	G.J. Fosmire, Am. J. Clin. Nutr., 51(1990), pp. 225-227
[35]	H.B. Gong, K. Wang, R. Strich, J.G. Zhou, J. Biomed. Mater. Res. B, 103B(2015), pp. 1632-1640
[36]	M. Erinc, W.H. Sillekens, R.G.T.M. Mannens, R.J. Werkhovenr, Magnesium Technology, TMS, New York (2009), pp. 209-214
[37]	Y.F. Zheng, X.N. Gu, F. Witte, Mater. Sci. Eng. R, 77(2014), pp. 1-34
[38]	Y.J. Chen, Z.G. Xu, C. Smith, J. Sankar, Acta Biomater., 10(2014), pp. 4561-4573
[39]	E. Mostaed, M. Sikora-Jasinska, A. Mostaed, S. Loffredo, A.G. Demir, B. Previtali, D. Mantovani, R. Beanland, M. Vedani, J. Mech. Behav. Biomed., 60(2016), pp. 581-602
[40]	P. Han, P.F. Cheng, S.X. Zhang, C.L. Zhao, J.H. Ni, Y.Z. Zhang, W.R. Zhong, P. Hou, X.N. Zhang, Y.F. Zheng, Y.M. Chai, Biomaterials, 64(2015), pp. 57-69
[41]	E.L. Zhang, D.S. Yin, L.P. Xu, L. Yang, K. Yang, Mater. Sci. Eng. C, 29(2009), pp. 987-993
[42]	X.N. Gu, W.R. Zhou, Y.F. Zheng, Y. Cheng, S.C. Wei, S.P. Zhong, T.F. Xi, L.J. Cheng, Acta Biomater., 6(2010), pp. 4605-4613
[43]	M. Hashizume, M. Yamaguchi, Mol. Cell. Biochem., 122(1993), pp. 59-64
[44]	M. Yamaguchi, H. Oishi, Y. Suketa, Biochem. Pharmacol., 36(1987), pp. 4007-4012
[45]	H. Hu, W. Zhang, Y. Qiao, X. Jiang, X. Liu, C. Ding, Acta Biomater., 8(2012), pp. 904-915
[46]	T.N. Phan, T. Buckner, J. Sheng, J.D. Baldeck, R.E. Marquis, Oral Microbiol. Immunol., 19(2004), pp. 31-38