Enlisting an army of plant viruses to their cause, materials researchers at the National Institute of Standards and Technology (NIST) have identified a small biomolecule that binds specifically to one of the key crystal structures of the bodythe calcium compound that is the basic building block of teeth and bone. With refinements, the researchers say, the new molecule can be a highly discriminating probe for a wide range of diagnostic and therapeutic applications related to bones and teeth.
Although they have somewhat different mechanical properties, the major structural component of both teeth and bones is a crystalline compound of calcium phosphate called hydroxyapatite. Subtle variations in the way the crystal forms account for the differences. Identifying and monitoring the formation of this particular crystal is of paramount importance to biomedical researchers working on a variety of problems including the remineralization of teeth to repair decay damage, the integration of prosthetic joints and tissue-engineered bone materials for joint and bone replacement, and cell-based therapies to regrow bone tissue.
To date, however, there is no specific, practical method to spot the formation of hydroxyapatite in living systems or tissue samples. Materials scientists can identify the crystal structure with high reliability by the pattern it makes scattering X rays, but it's a complex procedure, requires fairly pure samples and certainly can't be used on living systems. There are some widely used chemical assaysthe von Kossa assay, for examplebut these also are destructive tests, and more importantly they really test simply for the presence of the elements calcium or phosphorus. They can't distinguish, for example, between deposits of amorphous calcium phosphatea precursorand the hydroxyapatite crystal.
To find a more specific, less destructive probe, the NIST team used a relatively new technique called "phage display" that can rapi
|Contact: Michael Baum|
National Institute of Standards and Technology (NIST)