Science Without Frontiers: Down to the Bare Bone


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We may marvel at revolutionary new materials used to build aircraft and space stations, but none of these is nearly as complex as some natural hardy substances, such as bone. In fact, despite several decades of research, a full understanding of bone structure still escapes scientists.

Now Weizmann Institute researchers have taken an important step toward clarifying bone structure. This interdisciplinary research is led by Prof. Daniel Wagner of the Materials and Interfaces Department, who specializes in man-made composite materials, and Prof. Steve Weiner of the Structural Biology Department, an expert in biological materials. They have developed a sophisticated mathematical model that makes it possible to predict the mechanical properties of bone with unprecedented accuracy.

"Sometimes you can only fully understand a biological substance when you know how it works on the mechanical level, and this is precisely why our collaboration with materials experts is invaluable," Weiner says.

The basic building blocks of bone are tiny collagen fibers mineralized with calcium phosphate crystals. These are organized into arrays, which, in turn, are usually further folded into higher-order structures. This complexity, coupled with the difficulty of studying such dense material under an electron microscope, makes bone structure exceedingly hard to figure out.

The Wagner-Weiner model consists of mathematical equations that explain how the bone's various components affect its mechanical function -- for example, how the shape, arrangement and alignment of the tiny fibers and crystals affect a bone's elasticity or its ability to withstand pressure applied in a certain direction. The model's greatest value lies in predicting correlations between structure and function that are difficult or impossible to measure experimentally.

The Weizmann Institute scientists hope the model may some day help reproduce the beneficial aspects of bone structure in man-made materials. They have also begun applying their model to studies ultimately aimed at improving treatments for osteoporosis.

Taking part in this research were Wagner's M.Sc. student Udi Akiva and Weiner's former Ph.D. student Dr. Vivi Ziv, as well as Ilana Sabanay and Talmon Arad, both of the Electron Microscopy Unit