Towards refining Raman spectroscopy-based assessment of bone composition.

Various compositional parameters are derived using intensity ratios and integral area ratios of different spectral peaks and bands in the Raman spectrum of bone. The [Formula: see text]-, [Formula: see text]-,[Formula: see text]-, [Formula: see text] PO, and [Formula: see text] CO bands represent the inorganic phase while amide I, amide III, Proline, Hydroxyproline, Phenylalanine, δ(CH), δ(CH), and Formula: see text represent the organic phase. Here, using high-resolution Raman spectroscopy, it is demonstrated that all PO bands of bone either partially overlap with or are positioned close to spectral contributions from the organic component. Assigned to the organic component, a shoulder at 393 cm compromises accurate estimation of [Formula: see text] PO integral area, i.e., phosphate/apatite content, with implications for apatite-to-collagen and carbonate-to-phosphate ratios. Another feature at 621 cm may be inaccurately interpreted as [Formula: see text] PO band broadening. In the 1020-1080 cm range, the ~ 1047 cm [Formula: see text] PO sub-component is obscured by the 1033 cm Phenylalanine peak, while the ~ 1076 cm [Formula: see text] PO sub-component is masked by the [Formula: see text] CO band. With [Formula: see text] PO peak broadening, [Formula: see text] PO integral area increases exponentially and individual peaks comprising the [Formula: see text] PO band merge together. Therefore, [Formula: see text] PO and [Formula: see text] PO band profiles are sensitive to changes in mineral crystallinity.