Raman imaging of bone mineral and matrix: composition and function

We discuss the use of Raman microprobe spectroscopy and Raman imaging to study the chemical composition of fresh, unmounted bone at a microscopic level. A specimen of human cortical bone was analyzed and evidence for the presence of amorphous-type calcium phosphate, a theoretical precursor in the bone formation process, was found. In general the amorphous4ype calcium phosphate appears away from osteons, in the interstitial tissue. This finding calls into question the role of amorphous-type calcium phosphate as a precursor to apatitic phosphate, since it was not found in the recently remodeled bone near the osteon center, but rather in older bone tissue. Some reasons for the presence of amorphous calcium phosphate are proposed. Possible relations ofthe amorphous mineral to bone damage and bone remodeling are discussed.