title: Anisotropy in bone demineralization revealed by polarized far-IR spectroscopy.
abstract: Bone material is composed of an organic matrix of collagen fibers and apatite nanoparticles. Previously, vibrational spectroscopy techniques such as infrared (IR) and Raman spectroscopy have proved to be particularly useful for characterizing the two constituent organic and inorganic phases of bone. In this work, we tested the potential use of high intensity synchrotron-based far-IR radiation (50-500 cm(-1)) to gain new insights into structure and chemical composition of bovine fibrolamellar bone. The results from our study can be summarized in the following four points: (I) compared to far-IR spectra obtained from synthetic hydroxyapatite powder, those from fibrolamellar bone showed similar peak positions, but very different peak widths; (II) during stepwise demineralization of the bone samples, there was no significant change neither to far-IR peak width nor position, demonstrating that mineral dissolution occurred in a uniform manner; (III) application of external loading on fully demineralized bone had no significant effect on the obtained spectra, while dehydration of samples resulted in clear differences. (IV) using linear dichroism, we showed that the anisotropic structure of fibrolamellar bone is also reflected in anisotropic far-IR absorbance properties of both the organic and inorganic phases. Far-IR spectroscopy thus provides a novel way to functionally characterize bone structure and chemistry, and with further technological improvements, has the potential to become a useful clinical diagnostic tool to better assess quality of collagen-based tissues.
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, 14424 Potsdam, Germany. roman.schuetz@mpikg.mpg.de.
authors: Roman
authors: R
authors: Schuetz
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, 14424 Potsdam, Germany. dmbusg@gmail.com.
authors: Dmitri
authors: D
authors: Fix
authors: Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Methoden der Materialentwicklung, D-12489 Berlin, Germany. ulrich.schade@helmholtz-berlin.de.
authors: Ulrich
authors: U
authors: Schade
authors: Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Methoden der Materialentwicklung, D-12489 Berlin, Germany. emad.aziz@fu-berlin.de.
authors: Emad F
authors: EF
authors: Aziz
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, 14424 Potsdam, Germany. nadya.timofeeva@mpikg.mpg.de.
authors: Nadya
authors: N
authors: Timofeeva
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, 14424 Potsdam, Germany. richard.weinkamer@mpikg.mpg.de.
authors: Richard
authors: R
authors: Weinkamer
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, 14424 Potsdam, Germany. masic@mpikg.mpg.de.
authors: Admir
authors: A
authors: Masic
mesh_terms: D000818:Animals; D016880:Anisotropy; D001031:Apatites / Q000737:chemistry; D018775:Bone Demineralization Technique / Q000379:methods*; D015519:Bone Density; D002113:Calcification, Physiologic; D002417:Cattle; D003094:Collagen / Q000737:chemistry; D005269:Femur / Q000737:chemistry*; D008954:Models, Biological; D013055:Spectrophotometry, Infrared / Q000295:instrumentation* / Q000379:methods*
chemical_list: D001031:Apatites; D003094:Collagen