Raman spectroscopic investigation on the molecular structure of apatite and collagen in osteoporotic cortical bone. (January 2017)

• Record Type: Journal Article
• Authors: Pezzotti, Giuseppe; Rondinella, Alfredo; Marin, Elia; Zhu, Wenliang; Aldini, Nicolò Nicoli; Ulian, Gianfranco; Valdrè, Giovanni
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 65(2017)
• Page Start: 264
• Page End: 273
• Publication Date: 2017-01
• Subjects: Raman spectroscopy -- Apatite -- Collagen -- Bone; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2016.08.030
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: This study employed highly spectrally resolved Raman spectroscopy to examine the molecular composition of cortical bone tissue obtained from murine females in their healthy and ovariectomy- (OVX-) induced osteoporotic states. The aim of the study was to identify structural differences at the molecular scale both in apatite mineral and collagen fibrils between the two groups of samples. Raman spectroscopy was used to determine the chemical composition of cortical bone in regions including characteristic bands of both bone mineral and bone matrix. The results demonstrated that the mineral apatite of bone did not undergo significant amorphization in its diseased state, with the Raman microprobe also failing in recognizing a direct role of carbonate content in the embrittlement of OVX-diseased bone. On the other hand, complex off-stoichiometry variations could be detected in the columnar Ca-structure of the bony hydroxyapatite according to morphological variations of the Raman band belonging to the symmetric phosphate stretching ( A 1 ) band at ~959 cm −1 . A fundamental role was also recognized for collagen quality on the process of bone embrittlement. The so-called matrix maturity ratio, as systematically measured on Raman spectra in the Amide I region, increased with statistical significance in OVX-treated samples as compared to control samples. An 8% increase could be associated to a 115% increase in elastic stress intensification in the mineral phase of OVX-diseased tissue as compared to the control one, thus proving a degradation in the (elastic) energy-dissipative capacity of a diseased bone matrix. Graphical abstract: Highlights: Molecular composition of healthy/osteoporotic murine cortical bone was examined. No significant amorphization in mineral apatite was found in its diseased state. Complex off-stoichiometry variations in bony hydroxyapatite were detected. A fundamental role for collagen quality on bone embrittlement was recognized.