Biomedical Engineering Reference
In-Depth Information
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ISO/TS 80004-4:2011 Nanotechnologies—Vocabulary—Part 4: Nanostructured materials.
This document gives terms and definitions for materials in the field of nanotechnologies
where one or more components are nanoscale regions and the materials exhibit properties
attributable to the presence of those nanoscale regions. A nanostructured material has an
internal or surface structure with a significant fraction of features, grains, voids, or precipi-
tates in the nanoscale. Articles that contain nano-objects or nanostructured materials are
not necessarily nanostructured materials themselves.
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ISO/TS 80004-5:2011 Nanotechnologies—Vocabulary—Part 5: Nano/bio interface. This
document lists terms and definitions related to the interface between NMs and biology
with the intention of facilitating communications among those who have an interest in the
application or use of nanotechnologies in biology or biotechnology, or the use of biological
principles or matter in nanotechnology.
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ISO/TS 80004-7:2011 Nanotechnologies—Vocabulary—Part 7: Diagnostics and therapeu-
tics for healthcare. This document is applicable to the use of nanotechnologies in medical
diagnostics and therapeutics, and exploitation of material features at the nanoscale for
diagnostic or therapeutic purposes in relation to human diseases.
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ISO/TR 13121:2011, Nanomaterial risk evaluation. This document describes a process for
identifying, evaluating, addressing, and making decisions about, and communicating the
potential risks of, developing and using manufactured NMs. This is done in order to pro-
tect the health and safety of the public, consumers, workers, and the environment; offering
guidance on the information needed to make sound risk evaluations and risk management
decisions, as well as how to manage in the face of incomplete or uncertain information.
It includes methods to update assumptions, decisions, and practices and suggests methods
that organizations can use to be transparent and accountable in how they manage NMs.
It also describes a process of organizing, documenting, and communicating about these.
Owing to their high specific surface area, NMs have a higher free surface energy as compared to
their bulk counterparts. Thus, they often have the tendency to agglomerate or aggregate to reduce
their free energy. ISO/TS 27687 also gives definitions for particles clustered in agglomerates and
aggregates. The “agglomerate” is defined as a collection of weakly bound particles or aggregates,
or mixtures, of the two where the resulting external surface area is similar to the sum of the surface
areas of the individual components. “Aggregate” refers to a particle composed of strongly bonded
or fused particles where the resulting external surface area may be significantly smaller than the
sum of the calculated surface areas of the individual components. Here, the term “particle” refers
to a minute piece of matter with defined physical boundaries (ISO 14644-6:2007, ISO/TS 27687).
We can replace “particle” with “nanomaterial” for the definitions of NMs clustered in agglomerates
and aggregates.
NMs are of interest because of their unique optical, magnetic, electrical, and other properties
at this scale. These unique properties have the potential for great impacts in electronics, medicine,
and other fields. Two principal factors that cause the properties of NMs to differ significantly from
other materials are increased relative surface area and quantum confinement effects. NMs have a
much greater surface-area-to-volume ratio than their conventional forms. Accordingly, this trans-
lates to a very high surface reactivity with the surrounding surface, ideal for catalysis or sensor
applications. Quantum confinement effects can become much more important in determining the
material's properties and characteristics, leading to novel optical, electrical, and magnetic behaviors
relative to bulk materials without a change in the chemical composition. According to the quantum
confinement theory, electrons in the conduction band and holes in the valence band are spatially
confined by the potential barrier of the surface. Owing to the confinement of both electrons and
holes, the lowest energy optical transition from the valence to the conduction band will increase
in energy, effectively increasing the band gap. As a result, the absorption energy of quantum dots
will shift to higher frequencies with the decreasing diameter of the dots. This is readily observed
