http://www.nature.com/srep/2015/150529/srep10719/full/srep10719.html
In the 21st century, biodegradable metals (BMs), with the unique characteristic of degradation within body fluid and no need to withdraw by secondary surgery, have been the research hotspot in the field of biomaterials, and regarded as the revolutionized metallic biomaterial.
The previous works indicated that the degradation rate of Mg-based BMs were too slow whereas the degradation rate of Fe-based BMs were too fast, and to solve this problem, the research team of Prof. Zheng proposed the development of Zn-based BMs. The idea lies in that the electrode potential of element Mg is -2.37V and the electrode potential of element Fe is -0.440V, whereas the electrode potential of element Zn is -0.763V, just between elements Mg and Fe, and correspondingly the degradation rate will be slower than Mg but faster than Fe. Besides, Zn is an essential element with osteogenic potential of human body, whose bio-safety is out of question.
Moreover, since pure Zn is soft, brittle and has low mechanical strength, it should not be suitable for medical application, and the properties need to be further improved by alloying. In the present work, novel Zn-1X binary alloys, with the addition of nutrition elements Mg, Ca and Sr were designed (cast, rolled and extruded Zn-1Mg, Zn-1Ca and Zn-1Sr). Their microstructure and mechanical property, degradation and in vitro and in vivo biocompatibility were studied systematically.
The results demonstrated that the Zn-1X (Mg, Ca and Sr) alloys have profoundly modified the mechanical properties and in vivo biocompatibility of pure Zn. Zn-1X (Mg, Ca and Sr) alloys showed great potential for use in a new generation of biodegradable implants, opening up a new avenue in the area of biodegradable metals.
In recent years, Zheng’s team has been internationally active in the field of biodegradable metals (BMs). Seven papers had been selected as the ESI Highly Cited Paper, including Biomaterials 29 (2008) 1329-1344 (444 cited ), Biomaterials 30 (2009) 484-498 (349 cited), Biomaterials 31 (2010) 1093-1103 (118 cited), Acta Biomater 7 (2011) 1880-1889 (111 cited), Mater Sci Eng R 77 (2014) 1-34 (56 cited), Acta Biomater 10 (2014) 544-556 (17 cited), Corros Sci 79 (2014) 69-82(16 cited). Prof. Yufeng Zheng had been continuously invited to serve as the Chair of the International Symposium on Biodegradable Metals. The Ph.D dissertation of Xuenan Gu under the supervision of Prof. Yufeng Zheng had been awarded as “National Excellent Doctoral Dissertation” of 2013.
Based on the more than one decade of the leading research experience on this hot research field, Prof. Zheng has been invited by famous journal “Materials Science and Engineering R” (5 years Impact Factor: 21.676) to give the definition of BM for the first time, along with the summary of the recently developed representative BMs and the outlook of its future research and development direction (Biodegradable metals. Y.F. Zheng, et al. Materials Science and Engineering R 77 (2014) 1–34.)
This work was supported by the National Basic Research Program of China (973 Program) (Grant No. 2012CB619102), National Science Fund for Distinguished Young Scholars (Grant No. 51225101), National Natural Science Foundation of China (Grant No. 51431002 and 31170909), the NSFC/RGC Joint Research Scheme under Grant No. 51361165101 in Mainland China and N_CUHK449/13 in Hong Kong. The first author is Huafang Li (graduated in 2014), and the collaborators are Prof. Ling Qin and his team from Department of Orthopedics & Traumatology, the Chinese University of Hong Kong.
Representative histology of the cross-sections of mouse distal femoral shaft from Zn-1Mg, Zn-1Ca, Zn-1Sr implanted pins groups and the control group observed under fluorescent microscopy at week 8.
Edited by: Zhang Jiang
Source: College of Engineering
