Biomedical Engineering Reference
In-Depth Information
this chapter, with a few important exceptions, undoped and un-
substituted calcium orthophosphates are considered and discussed
only. The readers interested in various nanodimensional and
nanocrystalline ion-substituted calcium orthophosphates [25-52]
are referred to the original publications. Furthermore, details on
calcium orthophosphate-based nanodimensional biocomposites
[53-71] or nanodimensional calcium orthophosphate-based
biocomposites [72-87] are available in both Ref. [88] and section
6.4.3
of this topic.
This chapter is organized into several sections. After a brief
introduction (current section), general information on “nano” is
provided in the second section. The third section briefly compares
the micron-sized and nanodimensional calcium orthophosphates.
The forth section briefly discusses the presence of nano-sized and
nanocrystalline calcium orthophosphates in normal calcified tissues
of mammals. The structure of nano-sized and nanocrystalline apatites
is described in the fifth section. Synthesis of nanodimensional and
nanocrystalline calcium orthophosphates of various dimensions
and shapes is reviewed in the sixth section, while the biomedical
applications are examined in the seventh section. Finally, the
summary and reasonable future perspectives in this active research
area are given in the last section.
3.2
General Information on “Nano”
units. Although
it is widely accepted that the prefix “nano” specifically refers to 10
The prefix “nano” specifically means a measure of 10
−9
−9
units, in the context of nano-sized and nanocrystalline materials, the
units should only be those of dimensions, rather than of any other
unit of the scientific measurements. Besides, for practical purposes,
it appears to be unrealistic to consider the prefix “nano” to solely
and precisely refer to 10
−9
m, just as it is not considered that “micro”
specifically and solely concerns something with a dimension of
precisely 10
−6
m [89]. Currently, there is a general agreement that the
subject of nanoscience and nanotechnology started after the famous
talk: “There's plenty of room at the bottom” given by the Nobel
Prize winner in physics Prof. Richard P. Feynman on December 26,
1959, at the annual meeting of the American Physical Society held
at California Institute of Technology. This well-known talk has been
widely published in various media (e.g
.
,
[90]).
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