24.1

Introduction

Nanoparticles are small structures with a size range of 1–100 nm in at least one

dimension, while nanotechnology comprises the engineering of these nanoscale

structures at an atomic or molecular level. Nanoparticles can be synthesized or

produced from both organic and inorganic materials or can be natural or synthetic.

Various

organic

nanoparticles

include

polymeric

nanoparticles,

liposomes,

dendrimers, and micelles (Romero and Moya 2012), while inorganic nanoparticles

comprise quantum dots, carbon nanoparticles, magnetic iron oxide nanoparticles,

etc. (Giner-Casares et al. 2016). These nanoparticles, due to tuning of particle

morphology from micro- to nanosize, result in different characteristics compared

to their micron-sized counterparts which helps in their versatile applications. The

reason for unique and enhanced properties of these nanomaterials is their large

surface-to-volume ratio, high surface forces, higher percentage of atoms and

molecules on the surface, and quantum confinement effect.

Recently, a large focus has been towards the synthesis of different magnetic

nanoparticles (MNPs) with their extensive applications in a large number of fields

including biomedicine, biomedical, environmental remediation, and catalysis. As

one of unique nanomaterials, these nanoparticles possess not only the general

characteristics of nanomaterials but additional advantage of magnetic properties.

These nanoparticles exhibit their best performance at a typical size range from 10 to

20 nm. The low-dimensional structures are characterized by superior magnetic

moment

and

emergence

of

superparamagnetism

(Khanna

et

al.

2018).

Superparamagnetism results because of the thermal fluctuations which are suffi-

ciently strong to naturally demagnetize a previously saturated assembly; hence, these

nanoparticles display zero coercivity with the absence of hysteresis. Thus, the

external magnetic field applied can magnetize the nanoparticles with greater mag-

netic vulnerability. On removal of the magnetic field, these nanoparticles show no

magnetism. Due to superparamagnetic structures, they are able to respond immedi-

ately to magnetic fields applied. Moreover, these nanoparticles display large specific

surface area, large surface-to-volume ratio, facile separation under magnetic field,

and high mass transference, perfect characteristics for application in the field of

biomedicine (Niemirowicz et al. 2012). These nanoparticles consist of various

magnetic elements including iron, nickel, manganese, chromium, and cobalt and

their compounds. One of the distinctive advantages of these nanoparticles is that they

can be selectively attached to any functional molecule which allows their transpor-

tation under external magnetic field.

Magnetic nanoparticles, owing to their unique properties, are exceptional

nanostructures which find applications in all the application areas of medical science

including therapeutics, diagnostics, and imaging. There are diverse therapeutic

applications of MNPs ranging from delivery of drugs, antimicrobial agents,

vaccines, genes, and site-specific targeting to circumvent adverse effects of thera-

peutics (Parveen et al. 2012). Magnetic nanoparticles can be made biocompatible

with surface modification, and hence can be used as vectors, facilitating directional

transportation of drugs or genes under the influence of magnetic field to achieve

456

Renu et al.