Environmental Engineering Reference
In-Depth Information
biocompatibility point of view, and which are presenting an increased stability
against oxidation, which is crucial for certain application fields [
117
].
7.2.4 Applications of Magnetic Nanoparticles
Increased interest for magnetic nanoparticles can be explained due to diverse
applications of these compounds. The fields in which these particles are used are:
biomedical, catalysis, and industrial field. Magnetite particles (Fe
3
O
4
) dispersed in
a fluid were largely used as ferrofluids [
118
,
119
] in diverse applications, such as:
electric transformers, pressure transducers, inertial sensors (acceleration, slope,
gravity) [
120
], position sensors [
121
], devices for information storage [
122
], heat
transfer [
123
], optics [
124
,
125
], electronics [
126
], and biomedical engineering [
22
,
127
-
130
].
7.2.4.1 Applications in Biomedical Field
In case of biomedical applications, colloidal suspensions, obtained because of
magnetic nanoparticles dispersion in biological media, should have colloidal sta-
bility over a long period. The magnetic core of the particle should respond to an
external magnetic field, so that it could be directed and positioned in a certain
location, thus facilitating Magnetic Resonance Imaging (MRI) for medical diagno-
sis, as well as antitumor therapies assisted by alternative magnetic field.
Magnetite and/or maghemite nanoparticles are the most desired for biomedical
applications due to their strong ferromagnetic behavior, relatively decreased tox-
icity, decreased sensitivity to oxidation, as well as increased values of saturation
magnetization, compared to other materials (cobalt, nickel, more susceptible to
oxidation, with increased toxicity).
Regarding the use of nanoparticles in medical applications, these can be grouped
in two main categories: in vivo and in vitro applications. In vivo applications are
especially based on diagnostic procedures (MRI) and therapeutic applications
(hyperthermia, targeted drug delivery).
Main utilization of magnetic nanoparticles for in vitro experiments is related to
diagnosis (cellular separation and selection [
131
-
134
], and magnetic relaxometry
[
135
,
136
]).
Magnetic resonance imaging (MRI) is a non-invasive technique, without expo-
sure to radiations, which can give transversal imaging within solid material and
living organisms [
137
,
138
]. Development of MRI as clinical diagnostic tool
largely contributed to pharmaceutical products advance, generating so-called mag-
neto-pharmaceutical products. The purpose of these magneto-pharmaceutical prod-
ucts, in case of clinical use, is to increase the contrast between damaged and healthy
tissue, and/or to indicate the function of an organ or blood vessels [
139
].
