This document discusses the classification of nanoparticles. It begins by describing natural nanoparticles found in materials like skin, shells, corals and minerals. It then discusses synthesized nanoparticles which are fabricated using top-down or bottom-up methods. Nanoparticles are classified based on their material, which includes organic nanoparticles like dendrimers and liposomes, and inorganic nanoparticles like metals, ceramics and semiconductors. Nanoparticles are also classified based on their dimension, including zero-dimensional nanoparticles, one-dimensional nanotubes and nanofibers, two-dimensional nanosheets, and three-dimensional bulk materials.
2. 1. Classification of Nanoparticles and
Types of Nanomaterials
Group A . Natural Nanomaterials
3. We see multiple of examples of nanoscience under our eyes daily, from geckos to butterflies with
iridescent colors that glow at night. A short list of some natural nanomaterials follows:
1. Nanoparticles from natural erosion and volcanic activity: nanoparticles are part of our mineral
world since they are naturally produced during erosion and volcanic explosions.
2. Minerals, such as clays, are nanostructured: clays are a type of layered silicate characterised by
a fine 2D crystal structure. Among clays, mica has been the most studied. Mica is made up of
large sheets of silicate held together by relatively strong bonds.
3. Natural colloids, such as milk and blood (liquid colloids), fog (aerosol type), gelatin (gel
type): in these materials, nanoparticles are dispersed in the medium (liquid or gas) but do not
form a solution, rather a colloid. All these materials have the characteristic of scattering light and
often their color (as in the case of blood and milk) is due to the scattering of light by the
nanoparticles that make them up.
4. Mineralized natural materials, such as shells, corals and bones. Many of these materials are
formed by calcium carbonate crystals. That are self-assemble together with other natural
materials, such as polymers, to form fascinating three-dimensional architectures.
5. Materials like skin, claws, beaks, feathers, horns, hair: these materials are made largely of very
flexible proteins like keratin, elastin and collagen.
6. Paper and cotton: both are made mainly of cellulose. The high strength, durability and
absorbency of cotton are due to the nanoscale arrangement of the fibers.
4. Group B. Synthesized nanoparticles.
These nanoparticles group of nanoparticles are fabricated based on the two basic
categories synthesis processes bottom up or down up.
2. Classification of Nanoparticles Based on Materials
1. Organic NPs
This class comprises NPs that are made of proteins, carbohydrates, lipids, polymers,
or any other organic compounds. The most prominent examples of this class are
dendrimers, liposomes, micelles, and protein complexes such as ferritin.
Figure 1: Types of organic NPs. A Dendrimers; B liposomes; C micelles; and D ferritin
5. (a) Fullerenes: Fullerenes (C60) are spherical carbon molecules made up of carbon atoms
arranged in sp2hybridization. Fullerenes contain 28–1500 carbon atoms arranged in spherical
structures with a diameter of up to 8.2 nm for a single-layered fullerene and
4–36 nm for a multi-layered fullerene.
(b) Graphene: This is the carbon-containing network. The arrangement of carbon atoms
forms a hexagonal pattern in the graphene network and makes two-dimensional planar
surfaces. The thickness of a two-dimensional sheet is about 1–2 nm.
(c) Carbon nano tubes (CNTs): These are nanofoils made up of carbon-containing graphene.
The carbon atoms are arranged in honeycomblattice in carbon nanotubes and form hollow
cylinders of 0.7 nm diameter for a single-layered CNT and about 100 nm for a multi-layered
CNT. The length of CNT varies from a few μm to a few mm.
(d) Carbon nanofibers: The graphene nanofoils used in the production of carbon
nanofibers are the same as CNTs but the structure is different. The graphene molecules
are arranged in cone or cup form rather than the regular cylindrical tubes
of CNTs.
(e) Carbon black: This is an amorphous nanomaterial made up of carbon atoms that
are arranged in a spherical shape with diameters from 20 to 70 nm. The carbon black
particle interaction is so high that they bind with each other and form aggregates
around 500 nm.
6. Figure 2: Different types of carbon-based NPs. A C60 fullerene; B carbon black
NPs; and C carbon quantum dots.
7. 3.Inorganic-Based Nanomaterials
This class comprises NPs that not made of carbon or organic materials.
The typical examples of this class are metal, ceramic, and semiconductor
NPs. Metal NPs are purely made of metal precursors, they can be
monometallic, bimetallic, or polymetallic . Due to the localized surface
plasmon resonance characteristics, these NPs possess unique optical and
electrical properties. In addition, some metal NPs also possess unique
thermal, magnetic, and biological properties. This makes them
increasingly important materials for the development of nano devices
that can be used in numerous physical, chemical, biological, biomedical,
and pharmaceutical applications, (these applications are discussed in
detail later in the applications section of the review). In present days, the
size-, shape-, and facet-controlled synthesis of metal NPs is important for
creating cutting-edge materials.
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8. Composite-Based Nanomaterials
Composite nanomaterials are made up of one more layer
of nanoparticles. These nanomaterials are combined with
other nanoparticles, bulk materials, or more complex
materials like metal frameworks. The composites may be
made up of many types of materials such as metal,
ceramic, organic, inorganic, carbon-based, or bulk
polymers. These materials have different morphologies
depending on the synthesis and required properties for
the desired applications.
9. 3. Classification of Nanoparticles based
on Dimension
1- Zero-dimensional nanomaterials * Materials where in all the
dimensions are measured within the nanoscale (no dimensions,or 0-
D, are larger than 100 nm). * The most common representation of
zero-dimensional nanomaterials are nanoparticles. *Nanoparticles
can: * Be amorphous or crystalline * Be single crystalline or
polycrystalline * Be composed of single or multi-chemical elements
* Exhibit various shapes and forms * Exist individually or
incorporated in a matrix Be metallic, ceramic, or polymeric
10. 1- One-dimensional nanomaterials (1-D): the nanomaterials in this class have one
dimension outside the nanoscale. Examples are nanotubes, nanofibers, nanorods,
nanowires, and nanohorns. One dimension that is outside the nanoscale leads to
needle like-shaped nanomaterials. 1-D materials include nanotubes, nanorods, and
nanowires. 1-D nanomaterials can be Amorphous or crystalline Single crystalline or
polycrystalline Chemically pure or impure Standalone materials or embedded in
within another medium Metallic, ceramic, or polymeric
3- Two-dimensional nanomaterials (2-D): the nanomaterials in this class have two
dimensions outside the nanoscale. Examples are nanosheets, nanofilms, and
nanolayers. Two of the dimensions are not confined to the nanoscale. 2-D
nanomaterials exhibit plate-like shapes. The 2-D nanomaterials can be: Amorphous
or crystalline made up of various chemical compositions used as a single layer or as
multilayer structures deposited on a substrate Integrated in a surrounding matrix
material Metallic, ceramic, or polymeric.
11. 3- Three-dimensional nanomaterials (3-D) or bulk nanomaterials: In this class, the
materials are not confined to the nanoscale in any dimension. This class contains
bulk powders, dispersions of nanoparticles, arrays of nanowires and nanotubes, etc.
Bulk nanomaterials are materials that are not confined to the nanoscale in any
dimension. These materials are thus characterized by having three arbitrarily
dimensions above 100 nm.
Materials possess a nanocrystalline structure or involve the presence of features at
the nanoscale. In terms of nanocrystalline structure, bulk nanomaterials can be
composed of a multiple arrangement of nanosize crystals, most typically in different
orientations. With respect to the presence of features at the nanoscale, 3-D
nanomaterials can contain dispersions of nanoparticles, bundles of nanowires, and
nanotubes as well as multinanolayers. Three-dimensional space showing the
relationships among 0-D, 1-D, 2-D, and 3-D nanomaterials.
