The influence of transition metal ions on collagen mineralization

The ions in body fluid play an important role in bone formation besides being a synthesizing material. Transition metal ions Co2 +, Ni2 +, Zn2 +, Fe3 +, Mn2 +, Cu2 +, Cd2 + and Hg2 + doped hydroxyapatite (HAP)/collagen composites were synthesized successfully in the presence of collagen traces at mild acidic pH for the first time. However, the amount of doped Hg2 + and Cd2 + was relatively low. Meanwhile, through soaking the collagen sponge as a template in simulated body fluid (SBF) which contains different transition metal ions (Mn2 +, Cu2 +, Ni2 +, Co2 +, Cd2 +, Hg2 +), bone-like HAP/collagen composites were synthesized. Hg2 + had a certain inhibitory effect on the formation of HAP crystals on the surface of the collagen sponge while Co2 + can promote the formation of HAP on the collagen sponge. For both HAP/collagen composites and HAP/collagen sponge, it was found that transition metal ions Mn2 + had a significant effect on the morphology of HAP particles and could induce to form floc-like HAP particle aggregates.

► Mn2 + could induce to form floc-like HAP particle aggregates.
► The coverage of HAP could be increased significantly by Co2 + or decreased by Hg2 +.
► The beneficial trace elements were easily doped into HAP/collagen composite.
► The amount of doped harmful elements of Cd2 +and Hg2 + was relatively low.