Nanotechnology (sometimes shortened to "nanotech") is the manipulation of matter
on an atomic and molecular scale. The earliest, widespread description of nanotechnology
referred to the particular technological goal of precisely manipulating atoms and
molecules for fabrication of macroscale products, also now referred to as molecular
nanotechnology. A more generalized description of nanotechnology was subsequently
established by the National Nanotechnology Initiative, which defines nanotechnology
as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers.
This definition reflects the fact that quantum mechanical effects are important
at this quantum-realm scale, and so the definition shifted from a particular technological
goal to a research category inclusive of all types of research and technologies
that deal with the special properties of matter that occur below the given size
threshold. It is therefore common to see the plural form "nanotechnologies" as well
as "nano scale technologies" to refer to the broad range of research and applications
whose common trait is size. With a variety of potential applications, nanotechnologies
are key for the future and governments have invested billions of dollars in their
research. Through its National Nanotechnology Initiative, the USA has invested 3.7
billion dollars. The European Union has invested 1.2 billion and Japan 750 million
dollars. Nanotechnology as defined by size is naturally very broad, including fields
of science as diverse as surface science, organic chemistry, molecular biology,
semiconductor physics, microfabrication, etc. The associated research and applications
are equally diverse, ranging from extensions of conventional device physics to completely
new approaches based upon molecular self-assembly, from developing new materials
with dimensions on the nano scale to direct control of matter on the atomic scale.
Scientists currently debate the future implications of nanotechnology. Nanotechnology
may be able to create many new materials and devices with a vast range of applications,
such as in medicine, electronics, bio materials and energy production. On the other
hand, nanotechnology raises many of the same issues as any new technology, including
concerns about the toxicity and environmental impact of nano materials, and their
potential effects on global economics, as well as speculation about various doomsday
scenarios. These concerns have led to a debate among advocacy groups and governments
on whether special regulation of nanotechnology is warranted. Future prospects for
nanotechnology and biomaterials in medical applications appear to be excellent.
In orthopedic applications, there is a significant need and demand for the development
of a bone substitute that is bioactive and exhibits material properties (mechanical
and surface) comparable with those of natural, healthy bone. Particularly, in bone
tissue engineering, nanometer-sized ceramics, polymers, metals and composites have
been receiving much attention recently. This is a result of current conventional
materials (or those materials with constituent dimensions >1 microm) that have not
invoked suitable cellular responses to promote adequate osteointegration to enable
these devices to be successful for long periods. By contrast, owing to their ability
to mimic the dimensions of constituent components of natural bone (e.g., proteins
and hydroxyapatite), nanophase materials may be an exciting successful alternative
orthopedic implant material. In this article, the ability of novel nanomaterials
that promote osteointegration is discussed. Potential pitfalls or undesirable side
effects associated with the use of nanomaterials in orthopedic applications are
also reviewed.
