Biomedical Engineering Reference
In-Depth Information
Chapter 3
Biomineralization: Mechanisms
of Hydroxyapatite Crystal Growth
Kazuo Onuma, Toru Tsuji, and Mayumi Iijima
Abstract
Progress in the investigation of the growth mechanism of hydroxyapatite,
the most important biomineral, is described in relation to observation and measure-
ment techniques of crystals growing in aqueous solutions. Optical interferometry,
especially phase-shift interferometry, can measure the apatite growth rate precisely
and facilitates estimates of several growth parameters necessary to analyze the
growth mechanism of apatite. The data strongly suggest that the growth unit of
apatite takes the form of energetically stable clusters. Apatite growth proceeds
via accumulation of clusters, resembling the growth of macromolecular protein
crystals, although conventional spiral or two-dimensional nucleation growth occurs
on the surface, as in the case of protein crystals. Phase transformation of amorphous
calcium phosphate into apatite proceeds via direct structure reconstruction of ag-
gregates with clusters as the minimum unit. These cluster-based transformation and
growth phenomena are not specific to apatite: they also occur in other biominerals,
such as calcium carbonates.
Keywords
Biomineralization • Hydroxyapatite • Growth mechanism • Phase-
shift interferometry • Cluster
K. Onuma (
)
National Institute of Advanced Industrial Science & Technology, Central 6,
1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan
e-mail:
k.onuma@aist.go.jp
T. Tsuji
Advanced Research Centers, Keio University, 3-14-1, Hiyoshi, Kohoku-ku,
Yokohama, 223-8522, Japan
e-mail:
toruts2002@yahoo.co.jp
M. Iijima
Asahi University School of Dentistry, Oral Functional Science and Rehabilitation,
Dental Materials Science, 1851-1 Hozumi, Mizuho, Gifu, 501-0296, Japan
e-mail:
iijima@dent.asahi-u.ac.jp
