120
C. de Julián Fernández and F. Pineider
Among the most appealing properties of MP NPs is the combination of magnetic
and plasmonic properties and the multifunctional approach that can be reached with
these structures. Magnetoplasmonic systems were first considered to overcome many
of the limitations of plasmonic systems. MPs was one of the first concepts considered
to develop “active plasmonics” [171], i.e., plasmonics devices which SPR, and hence
the optical properties, could be manipulated externally [12, 14, 171–174]. The optical
properties of the MP particles are modulated by an external magnetic field as a
consequence of the change of their magneto-optical properties (see next section).
Another path to modulate the optical properties is the design of asymmetric structures,
as stars, in which a rotating magnetic field induces the movement (rotation) of the
particles that gives rise to time-dependent changes of the reflectivity [27, 175, 176].
A second contribution of MPs concerns the improvement of the possibilities of manipulation of the plasmonic systems for biomedical targeting therapies
(Fig. 5.4ii, iii, iv). In fact, the efficiency of plasmonic structures for drug or gene
delivery, for targeting and for separation is determined by the possibilities of functionalization and anchoring to the targets [151]. Adding the possibilities of the
spatial manipulation with a magnetic field gradient it is possible to improve the
drug-delivery, tracking, intracellular drag update, and the particle retentivity in invivo applications [150, 177, 178]. In in-vitro tests and lab-on-chip applications it
is possible to drag the particles, to localize and to concentrate the target molecules,
genes, DNA and hence to improve sensibility of devices between other properties
[153–157, 179].
Regarding the thermal therapy approach, both photo-thermia and magnetic hyperthermia methods can be simultaneously applied in MP NPs [35, 97, 121, 151, 180,
181]. As was previously discussed, the choice of MP structures can improve critical questions related to the employment of each class of particles in therapy, i.e.
the cytotoxicity and the elimination of magnetic particles and the application of
plasmon-assisted photo-thermal therapy in the NIR. In fact, photo-thermia can only
be applied to targets placed at few centimeters from the skin, employing NIR radiation, while magnetic fields can be designed to reach deeper areas. Recent studies
have outlined the improvement of the local thermal heating combining simultaneously the two procedures [97, 133, 180, 183] (Fig. 5.4i). Some studies indicate that
the improvement is due to combination of the two thermal processes rather than to a
synergistic effect [97, 182, 183].
Considering the activity of the plasmonic and magnetic moieties as probes, optical
(photoacoustic, pholuminescence) and magnetic (NMR, ultrasound, magnetic,
magneto-motive) imaging techniques can be combined in a multimodalapproach
[15, 63, 65, 117, 128, 130, 134, 151, 177, 184, 185] with MPs NPs (Fig. 5.3iii, iv).
Different types of imaging probes, like Vis and IR light, ultrasounds and radiofrequency (NMR), new imaging methods, like optical magneto-motive [163, 164] and
magneto-optical techniques designed with MP NPs, and other clinical tests like
positron emission Tomography or X-ray computed tomography [128, 179, 184–
186] can be simultaneously employed to obtain images at penetration larger than the
optical threshold of each probe. In addition better spatially resolved and complementary information can be obtained. Also enhanced imaging sensitivity and accuracy is
C. de Julián Fernández and F. Pineider
Among the most appealing properties of MP NPs is the combination of magnetic
and plasmonic properties and the multifunctional approach that can be reached with
these structures. Magnetoplasmonic systems were first considered to overcome many
of the limitations of plasmonic systems. MPs was one of the first concepts considered
to develop “active plasmonics” [171], i.e., plasmonics devices which SPR, and hence
the optical properties, could be manipulated externally [12, 14, 171–174]. The optical
properties of the MP particles are modulated by an external magnetic field as a
consequence of the change of their magneto-optical properties (see next section).
Another path to modulate the optical properties is the design of asymmetric structures,
as stars, in which a rotating magnetic field induces the movement (rotation) of the
particles that gives rise to time-dependent changes of the reflectivity [27, 175, 176].
A second contribution of MPs concerns the improvement of the possibilities of manipulation of the plasmonic systems for biomedical targeting therapies
(Fig. 5.4ii, iii, iv). In fact, the efficiency of plasmonic structures for drug or gene
delivery, for targeting and for separation is determined by the possibilities of functionalization and anchoring to the targets [151]. Adding the possibilities of the
spatial manipulation with a magnetic field gradient it is possible to improve the
drug-delivery, tracking, intracellular drag update, and the particle retentivity in invivo applications [150, 177, 178]. In in-vitro tests and lab-on-chip applications it
is possible to drag the particles, to localize and to concentrate the target molecules,
genes, DNA and hence to improve sensibility of devices between other properties
[153–157, 179].
Regarding the thermal therapy approach, both photo-thermia and magnetic hyperthermia methods can be simultaneously applied in MP NPs [35, 97, 121, 151, 180,
181]. As was previously discussed, the choice of MP structures can improve critical questions related to the employment of each class of particles in therapy, i.e.
the cytotoxicity and the elimination of magnetic particles and the application of
plasmon-assisted photo-thermal therapy in the NIR. In fact, photo-thermia can only
be applied to targets placed at few centimeters from the skin, employing NIR radiation, while magnetic fields can be designed to reach deeper areas. Recent studies
have outlined the improvement of the local thermal heating combining simultaneously the two procedures [97, 133, 180, 183] (Fig. 5.4i). Some studies indicate that
the improvement is due to combination of the two thermal processes rather than to a
synergistic effect [97, 182, 183].
Considering the activity of the plasmonic and magnetic moieties as probes, optical
(photoacoustic, pholuminescence) and magnetic (NMR, ultrasound, magnetic,
magneto-motive) imaging techniques can be combined in a multimodalapproach
[15, 63, 65, 117, 128, 130, 134, 151, 177, 184, 185] with MPs NPs (Fig. 5.3iii, iv).
Different types of imaging probes, like Vis and IR light, ultrasounds and radiofrequency (NMR), new imaging methods, like optical magneto-motive [163, 164] and
magneto-optical techniques designed with MP NPs, and other clinical tests like
positron emission Tomography or X-ray computed tomography [128, 179, 184–
186] can be simultaneously employed to obtain images at penetration larger than the
optical threshold of each probe. In addition better spatially resolved and complementary information can be obtained. Also enhanced imaging sensitivity and accuracy is