Nanoscale modifications in the early heating stages of bone are heterogeneous at the microstructural scale

Abstract

Nanoscale studies of bone provide key indicators to evidence subtle structural changes that may occur in the biomedical, forensic and archaeological contexts. One specific problem encountered in all those disciplines, for which the identification of nanostructural cues could prove useful, is to properly monitor the effect of heating on bone tissue. In particular, the mechanisms at work at the onset of heating are still relatively unclear. Using a multiscale approach combining Raman microspectroscopy, transmission electron microscopy (TEM), synchrotron quantitative scanning small-angle X-ray scattering imaging (qsSAXSI) and polarized light (PL) microscopy, we investigate the ultrastructure of cortical bovine bone heated at temperatures < 300°C, from the molecular to the macroscopic scale. We show that, despite limited changes in crystal structure, the mineral nanoparticles increase in thickness and become strongly disorganized upon heating. Furthermore, while the nanostructure in distinct anatomical quadrants appears to be statistically different, our results demonstrate this stems from the tissue histology, i.e. from the high degree of heterogeneity of the microstructure induced by the complex cellular processes involved in bone tissue formation. From this study, we conclude that the analysis of bone samples based on the structure and organization of the mineral nanocrystals requires performing measurements at the histological level, which is an advantageous feature of qsSAXSI. This is a critical aspect that extends to a much broader range of questions relating to nanoscale investigations of bone, which could also be extended to other classes of nanostructured heterogeneous materials.

Manipulating the Amount and Structure of the Organic Matrix Affects the Water Compartments of Human Cortical Bone

“…Also, differences in the post-processing of the spectra could also affect the sensitivity to thermal-related changes in RS properties of bone. Lastly, using X-ray diffraction techniques, Gourrier and colleagues (40) also found that the thickness of mineral crystals increased as the heating temperature increased, and this ultrastructural change may have translated to the higher crystallinity by RS observed in the present study. How such a change affects bound water is unknown.…”

Ultrafine heat-induced structural perturbations of bone mineral at the individual nanocrystal level

“…Most X-ray studies concluded an absence of mineral crystal structure modifications before 400 °C, while a rapid crystal growth has been reported at ~ 750 °C [18][19][20]. In a recent study we provided evidence that the mineral nanocrystals increase in size and become more disorganized at temperatures as low as 100 °C [21]. In addition, many debates remain open concerning the nature of a postulated high temperature phase transition, the coexistence of different crystallographic phases, as well as the presence of ionic defects above and below the critical temperature of Tcr = 750 °C [22].…”

Crystal clear: Vibrational spectroscopy reveals intrabone, intraskeleton, and interskeleton variation in human bones

“…As Thompson et al () stated previously, it is possibly related with differences in bone structure and bone remodeling, which have been found between trabecular and compact bone (Reznikov et al, ). Intrabone heterogeneity in histological tissue has also been identified as a cause for heat‐induced nanoscale differences in the variance of particle thicknesses (Gourrier et al, ). In particular, Gourrier et al () detected differences in the nanoscale properties of osteonal vs interstitial tissue and fibrous vs fibrolamellar tissue.…”

“…When present, all of the long bones, metacarpals, metatarsals, and tarsals from both left and right sides of each skeleton were used (Table ). Human bones are quite variable in terms of structure, shape and size, and such variables may in some way interfere with bone parameters, especially with crystallinity (Reznikov, Chase, Brumfeld, Shahar, & Weiner, ; Gourrier et al, ). Therefore, three different bone types were investigated.…”

“…Bone composition can be altered by several taphonomic agents, including weathering, fossilization, grinding and heating (Stiner, Kuhn, Weiner, & Bar‐Yosef, ; Michel, Ildefonse, & Morin, ; Surovell & Stiner, ; Munro, Longstaffe, & White, ; Piga et al, 2009, 2011; Thompson et al, ). In particular, heat‐induced changes have been the focus of numerous studies (e.g., Piga, Malgosa, et al 2008; Piga, Thompson, et al, 2009; Thompson et al, ; Beasley et al, ; Galeano & García‐Lorenzo, ; Piga, Gonçalves, et al, 2016; Cascant et al, ; Gourrier et al, ). Heat‐induced transformation of bone undergoes four different stages (Mayne‐Correia, ; Thompson, ; Etok et al, ): (i) dehydration, at temperatures between 100°C and 600°C; (ii) decomposition, at 300–800°C leading to the pyrolysis of organic components; (iii) inversion, corresponding to changes in the inorganic phase, at 500–1100°C; and (iv) fusion, taking place above 700°C and prompting crystal coalescence.…”