14 Medical Applications of Magnetic Nanoparticles
329
far from being realized. MNPs could offer a unique possibility to by-pass this hurdle,
as they can be driven to a desired site by the application of an external magnetic field
gradient (magnetic targeting) [7].
An overview of some of the many applications where MNPs have been proposed
as main players is provided in Sect. 4.1 (Smart platforms for biomedical applications).
Here, we will focus on the two most important ones, namely, magnetic resonance
imaging (MRI) and magnetic fluid hyperthermia (MFH), whose impact has already
been (MRI) or is expected to be in the next future (MFH) fundamental in clinics,
both as diagnostic and therapeutic tools [1].
14.2 Magnetic Resonance Imaging and Magnetic Fluid
Hyperthermia: An Overview
Nuclear magnetic resonance (NMR) is a powerful technique that has come into
being in 1946, when pioneer scientists as Bloch [8] and Purcell [9] firstly discovered
the possibility to manipulate the time evolution of the nuclear magnetization by
applying radiofrequency (RF) pulse sequences. The RF field has the capability to
slightly perturb a system generating a resonance signal that behaves as a fingerprint of
its characteristics, therefore, providing multiple information about the system itself.
The type of information acquired by the NMR analysis depends on the design of
the RF pulse sequence [10, 11]. The advantages of NMR are its high versatility and
a very low invasiveness, since differently from other diagnostic techniques such as
computed tomography (CT), it makes no use of ionizing radiations. Moreover, the
versatility of this technique, which allows obtaining multiple information depending
on the RF pulses sequence designed for a specific diagnostic purpose, led to a rapid
spread of magnetic resonance imaging (MRI) apparatus in the hospitals [12–15].
The dissemination of different kinds of contrast agents (CAs), which increased
the readability of the MR images, has improved further the development of MRI in
the latest decades. At first, paramagnetic molecules (for example, Gadolinium-based
agents) were applied to affect the nuclear relaxation times on the site of interest [16].
Subsequently, and particularly in the latest years, an increasing interest in the field
of nanomedicine led to the development of nanoparticles made of biocompatible
magnetic materials, typically iron oxides, which act as efficient CA.
Contrary to MRI, which has been routinely employed in clinics for several years,
magnetic fluid hyperthermia application as therapeutic tool is still limited to a few
experimental cases. Despite MFH has been approved in Europe for glioblastoma
multiforme, clinical trials involving this technique have been conducted solely by
MagForce (Berlin, Germany) for treating glioblastoma, prostate, and other kinds of
cancers [17, 18]. Although some important steps have been done in the last decades,
further work is needed for translating MFH to the clinic, and thus, fully exploit
the great potential of this promising cancer therapy. The attractiveness of MFH
329
far from being realized. MNPs could offer a unique possibility to by-pass this hurdle,
as they can be driven to a desired site by the application of an external magnetic field
gradient (magnetic targeting) [7].
An overview of some of the many applications where MNPs have been proposed
as main players is provided in Sect. 4.1 (Smart platforms for biomedical applications).
Here, we will focus on the two most important ones, namely, magnetic resonance
imaging (MRI) and magnetic fluid hyperthermia (MFH), whose impact has already
been (MRI) or is expected to be in the next future (MFH) fundamental in clinics,
both as diagnostic and therapeutic tools [1].
14.2 Magnetic Resonance Imaging and Magnetic Fluid
Hyperthermia: An Overview
Nuclear magnetic resonance (NMR) is a powerful technique that has come into
being in 1946, when pioneer scientists as Bloch [8] and Purcell [9] firstly discovered
the possibility to manipulate the time evolution of the nuclear magnetization by
applying radiofrequency (RF) pulse sequences. The RF field has the capability to
slightly perturb a system generating a resonance signal that behaves as a fingerprint of
its characteristics, therefore, providing multiple information about the system itself.
The type of information acquired by the NMR analysis depends on the design of
the RF pulse sequence [10, 11]. The advantages of NMR are its high versatility and
a very low invasiveness, since differently from other diagnostic techniques such as
computed tomography (CT), it makes no use of ionizing radiations. Moreover, the
versatility of this technique, which allows obtaining multiple information depending
on the RF pulses sequence designed for a specific diagnostic purpose, led to a rapid
spread of magnetic resonance imaging (MRI) apparatus in the hospitals [12–15].
The dissemination of different kinds of contrast agents (CAs), which increased
the readability of the MR images, has improved further the development of MRI in
the latest decades. At first, paramagnetic molecules (for example, Gadolinium-based
agents) were applied to affect the nuclear relaxation times on the site of interest [16].
Subsequently, and particularly in the latest years, an increasing interest in the field
of nanomedicine led to the development of nanoparticles made of biocompatible
magnetic materials, typically iron oxides, which act as efficient CA.
Contrary to MRI, which has been routinely employed in clinics for several years,
magnetic fluid hyperthermia application as therapeutic tool is still limited to a few
experimental cases. Despite MFH has been approved in Europe for glioblastoma
multiforme, clinical trials involving this technique have been conducted solely by
MagForce (Berlin, Germany) for treating glioblastoma, prostate, and other kinds of
cancers [17, 18]. Although some important steps have been done in the last decades,
further work is needed for translating MFH to the clinic, and thus, fully exploit
the great potential of this promising cancer therapy. The attractiveness of MFH