In vivo corrosion mechanism by elemental interdiffusion of biodegradable Mg-Ca alloy.
We elucidated the in vivo corrosion mechanism of the biodegradable alloy Mg-10 wt % Ca in rat femoral condyle through transmission electron microscope observations assisted by focused ion beam technique. The alloy consists of a primary Mg phase and a three-dimensional lamellar network of Mg and Mg(2)Ca. We found that the Mg(2)Ca is rapidly corroded by interdiffusion of Ca and O, leading to a structural change from lamellar network to nanocrystalline MgO. In contrast to the fast corrosion rate of the lamellar structure, the primary Mg phase slowly changes into nanocrystalline MgO through surface corrosion by O supplied along the lamellar networks. The rapid interdiffusion induces an inhomogeneous Ca distribution and interestingly leads to the formation of a transient CaO phase, which acts as a selective leaching path for Ca. In addition, the outgoing Ca with P from body fluids forms needle-type calcium phosphates similar to hydroxyl apatite at interior and surface of the implant, providing an active biological environment for bone mineralization.
Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
Jae-Young
JY
Jung
Sang-Jun
SJ
Kwon
Hyung-Seop
HS
Han
Ji-Young
JY
Lee
Jae-Pyoung
JP
Ahn
Seok-Jo
SJ
Yang
Sung-Youn
SY
Cho
Pil-Ryung
PR
Cha
Yu-Chan
YC
Kim
Hyun-Kwang
HK
Seok
D020341:Absorbable Implants; D000818:Animals; D018786:Bone Substitutes / Q000737:chemistry*; D002113:Calcification, Physiologic; D002118:Calcium / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry; D003343:Corrosion; D017886:Durapatite / Q000378:metabolism*; D008274:Magnesium / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry; D008422:Materials Testing; D053758:Nanoparticles / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D051381:Rats
D018786:Bone Substitutes; D017610:Calcium Compounds; D010087:Oxides; D008277:Magnesium Oxide; D017886:Durapatite; C016538:lime; D008274:Magnesium; D002118:Calcium