26.4

Classification of Nanoparticles

There are four material-based categories in which NPs and nanosized materials may

be organised (Table 26.1).

1. Carbon-based NPs: These types of NPs are mainly formed of carbon. Examples

of their morphology are hollow tubes, ellipsoids, etc. These could be further

classified into fullerenes, carbon black, carbon nanotubes (CNT), graphene,

carbon nanofibres and activated carbon in nanosize (Kumar and Kumbhat 2016).

2. Organic NPs: These NPs unlike carbon-based NPs are made up of organic matter.

Non-covalent interactions (being weak) are helpful for self-assembly and design

of molecule in transformation of organic NPs into desired structure such as

liposomes, dendrimers, micelles, ferritin, etc. (Tiwari et al. 2008). These NPs

are mostly biodegradable and non-toxic, among which some form hollow core

(such as micelles and liposomes) also known as nano-capsules, and they become

sensitive to electromagnetic and thermal radiation. This characteristic makes such

NPs as an ideal choice for drug delivery (Ealia and Saravanakuma 2017; Khan

et al. 2017).

3. Inorganic NPs: Inorganic NPs are hydrophilic, non-toxic and biocompatible and

highly stable when compared to organic materials. These are the metal and their

oxide-based NPs. They have certain types into which they can be synthesized, out

of which metals may include Au- or Ag-NPs (Salavati-Niasari et al. 2008);

similarly metal oxides may include TiO2, ZnO and even some semiconductors

like silicon and ceramics (Tai et al. 2007).

4. Composite NPs: These are NPs of composite structures, including core shell

structure, onion-like structure and gladiate composition. These NPs are

multiphased, with one of their phases of nanoscale dimension. This characteristic

helps them to combine different NPs and for a hybrid nanofibres structure or

complicated structures as metallic organic frameworks. These composites can be

Table 26.1 Classification of nanoparticles

S. no.

Type of NPs

Sub-type

Example

1

Carbon

Fullerenes

Graphene

Carbon nanotubes

Carbon nanofibres

Carbon black

TiO2

2

Organic

Dendrimers

Liposomes

Micelles

CdSe

3

Inorganic

Metal-based

Metal oxide-based

Au and Ag

ZnO and TiO2

4

Composite

Simple hybrid

Core or shell structured

Multifunctional quantum dots

SiO2

26

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