Bone Formation Images May Advance Development of Bone-Replacement Materials

This 3-D electron microscopy image shows calcium carbonate crystals growing to the organic surface. The flat part of the crystals, approximately 400 nm wide, is in contact with the organic layer.

Researchers at Eindhoven University of Technology (TU/e) have for the first time made high-resolution images of the earliest stages of bone formation. They used the world’s most advanced electron microscope to make three-dimensional images of the nanoparticles that are at the heart of the process. The results provide improved understanding of bone, tooth and shell formation. For industrial applications, the research holds promise for the development of better materials and processes based on nature itself. The findings are published in the 13 March issue of Science and reported online by ScienceDaily.

Led by Dr. Nico Sommerdijk, the researchers imaged small clusters with a 0.7-nm cross-section in a solution of calcium carbonate, which is the basic building block of shells. They showed for the first time that these clusters, each of which consists of only about ten ions, are at the genesis of the growth process by which the crystalline biomineral is ultimately formed. A special electron microscope from FEI Co. (Hillsboro, OR, USA ) called the cryoTitan enabled the team to be the first in its field of research to capture three-dimensional images of very rapidly frozen samples. The images showed how the clusters in the solution nucleate into larger, unstructured nanoparticles with an average diameter of around 30 nm.

An organic surface applied by the researchers ensures that these nanoparticles can grow into larger particles. Crystalline regions form by an ordering of the ions. The TU/e researchers also demonstrated a second function of the organic layer: it precisely controls the direction in which the mineral can grow into a full-fledged biomineral. They now hope to show that the mechanism they have identified also applies to the formation of other crystalline biominerals, and perhaps even to other inorganic materials.

This research has great importance in relation to bone growth and the development of bone-replacement materials. In addition, it could be used to control the growth of nanoparticles by subtle interactions between organic and inorganic materials much like what seems to happen in nature.

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Tags: bone research, cryotitan, Eindhoven University of Technology, Imaging, Nico Sommerdijk