Nanoanalytical Electron Microscopy Reveals a Sequential Mineralization Process Involving Carbonate-Containing Amorphous Precursors
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
A direct observation and an in-depth characterization of the steps by which bone mineral nucleates and grows in the extracellular matrix during the earliest stages of maturation, using relevant biomineralization models as they grow into mature bone mineral, is an important research goal. To better understand the process of bone mineralization in the extracellular matrix, we used nanoanalytical electron microscopy techniques to examine an in vitro model of bone formation. This study demonstrates the presence of three dominant CaP structures in the mineralizing osteoblast cultures: <80 nm dense granules with a low calcium to phosphate ratio (Ca/P) and crystalline domains; calcium phosphate needles emanating from a focus: “needle-like globules” (100–300 nm in diameter) and mature mineral, both with statistically higher Ca/P compared to that of the dense granules. Many of the submicron granules and globules were interspersed around fibrillar structures containing nitrogen, which are most likely the signature of the organic phase. With high spatial resolution electron energy loss spectroscopy (EELS) mapping, spatially resolved maps were acquired showing the distribution of carbonate within each mineral structure. The carbonate was located in the middle of the granules, which suggested the nucleation of the younger mineral starts with a carbonate-containing precursor and that this precursor may act as seed for growth into larger, submicron-sized, needle-like globules of hydroxyapatite with a different stoichiometry. Application of analytical electron microscopy has important implications in deciphering both how normal bone forms and in understanding pathological mineralization.
Date Issued
2016-07-06
Date Acceptance
2016-07-06
Citation
ACS Nano, 2016, 10 (7), pp.6826-6835
ISSN
1936-086X
Publisher
American Chemical Society
Start Page
6826
End Page
6835
Journal / Book Title
ACS Nano
Volume
10
Issue
7
Copyright Statement
This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, © 2016 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acsnano.6b02443.
Sponsor
Commission of the European Communities
Grant Number
ERC-2013-CoG-616417
Subjects
Nanoscience & Nanotechnology
MD Multidisciplinary
Publication Status
Published