Nanocomposites for artificial bone

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31 July 2007 NanoTechWeb
Nanocomposites for artificial bone

Belle Dumé

A new way to make artificial bone has been developed by researchers in Singapore. Susan Liao of the National University of Singapore and colleagues mixed various concentrations of collagen and carbonate to make a nanosized inorganic phase that resembles natural bone. The technique also allows different types of bone structure and dentine to be made for the first time.

Human bone is mainly composed of 65% hydroxyapatite nanocrystals and 25% collagen fibres. In dentine, which is found in teeth, this changes to about 70% hydroxyapatite and 20% collagen.

Scientists have tried to make nanosized artificial bone materials using various methods before now and have recently turned their attention to mineralised collagen, a nanoapatite/collagen composite. This material is highly biocompatible and has the nanostructure of artificial bone. It could be used in bone grafts and bone-tissue engineering, among other applications.

Liao and colleagues decided to fabricate this material to try and understand the effect of changing the carbonate and collagen concentrations on the final nano-hydroxyapatite composite structure. The researchers began by adding calcium, phosphate, and carbonate ions to a solution of collagen. Next, they adjusted the pH to induce the formation of the nanocomposite. They then varied the concentrations of the carbonate and collagen in solution and looked at the structure of the resulting nanomaterial using X-ray diffraction.

With higher collagen content, Liao and co-workers found that the nanocomposite contained smaller crystals. In contrast, with higher carbonate content, the plate-like crystals of the composites gradually turned into needle-like crystals that slowly became shorter, finally becoming spherical particles. This is the way that bone is formed naturally.

"Ours is the first study to show that the carbonate content can induce the morphological change of nano-hydroxyapatite with collagen," Liao told nanotechweb.org. The result could help scientists discover why natural bone incorporates different amounts of carbonate in different parts of the body, for example in teeth.

The team now plans to make the material with the same nanofibrous architecture as that in natural bone.


Source: http://nanotechweb.org/articles/news/6/7/26/1

Story posted: 31st July 2007