Raman spectroscopic investigation on the molecular structure of apatite and collagen in osteoporotic cortical bone.
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 (A1) band at ~959cm-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.
Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan. Electronic address: pezzotti@kit.ac.jp.
Giuseppe
G
Pezzotti
Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan.
Alfredo
A
Rondinella
Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan.
Elia
E
Marin
Department of Medical Engineering for Treatment of Bone and Joint Disorders, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0854, Japan.
Wenliang
W
Zhu
Laboratory of Preclinical and Surgical Study - Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy.
Nicolò Nicoli
NN
Aldini
Department of Biological, Geological, and Environmental Sciences, University of Bologna, Piazza di Porta S. Donato 1, 40126 Bologna, Italy.
Gianfranco
G
Ulian
Department of Biological, Geological, and Environmental Sciences, University of Bologna, Piazza di Porta S. Donato 1, 40126 Bologna, Italy. Electronic address: giovanni.valdre@unibo.it.
Giovanni
G
Valdrè
D000818:Animals; D001031:Apatites / Q000032:analysis*; D003094:Collagen / Q000648:ultrastructure*; D000071538:Cortical Bone / Q000473:pathology*; D005260:Female; D051379:Mice; D015394:Molecular Structure; D010024:Osteoporosis / Q000473:pathology*; D013059:Spectrum Analysis, Raman
D001031:Apatites; D003094:Collagen
Apatite; Bone; Collagen; Raman spectroscopy