13 Magnetic Nanoparticles for Life Sciences Applications
305
in the applications just mentioned. In addition, the capability of magnetic nanoparticles to interact with a magnetic field increases the possibilities for their exploitation.
For instance, in the same way as nanoparticles can act as vehicles for magnetically targeted drug delivery in chemotherapy against cancer [34, 35] they could be
implemented in phytosanitary treatments, for the selective and controlled delivery of
agrochemicals or other biomolecules, or to induce genetic transformations etc. [13].
Also in the analogy with biomedical applications, magnetic nanoparticles could play
a role as MRI contrast agents for plant research. In fact this technique is as well suitable for studying the health of a plant in a non-destructive way [36], and has made
possible the study of the modifications of the biophysical parameters of a cucumber
plant as response to environmental changes [37], the changes in the dynamics of the
sap flow [38], or the damage induced by plant parasitic nematodes and soil borne
pathogens on sugar beet plants [39]. Even the localized heating by magnetic hyperthermia [40] might be as well a useful treatment in agriculture and agronomy. As
suggested by Pérez de Luque and Rubiales [13], it might be applied to eliminate
parasitic weeds, assuming that nanoparticles are able to accumulate in a specific
plant organ. This could be the case, for example, of tubercles in Orobanche crenata,
where the nanoparticles (administered for example by the roots) would accumulate
due to their sink effect.
As is well known, magnetic nanoparticles can be coated with biocompatible materials as silica [41, 42], dextran [43], polyvinyl alcohol (PVA) [44], poly(ethylene
glycol) (PEG) [45] etc., which allows modifying the particle surface with a large
number of molecules of biological interest, and therefore broadening the functionality of the nanoparticle. The coating can be functionalized with bio-molecules, as
for instance antibodies [46, 47], able to recognize a specific pathogen in a culture or
soil, making the nanoparticle act as a magnetic label for the pathogen to be detected
by a biosensor [17, 18, 48]. The diversity of materials that can be used as coating
and the wide variety of functionalization protocols make the magnetic nanoparticles
very promising tools for plant biology and biotechnology.
In the following sections we will deal with two types of core-shell magnetic
nanoparticles. In the first case, they consist of an iron core coated with
graphite/graphene layers; from here on they will be called carbon-coated
(Fe@C) nanoparticles. The second type is magnetite coated with silica (i.e.,
Fe 3 O 4 @SiO 2 ) nanoparticles; this coating, besides being biocompatible, stable and
suitable for the encapsulation of biomolecules, [49] is very easy to be functionalized
with biological moieties [46]. Likewise, the biocompatibility of the Fe@C nanoparticles has been successfully tested in in vitro and in vivo animal models [35, 50,
51]. In particular, the experiments carried out in New Zeeland rabbits have shown
that these nanoparticles, once injected into the animal, can be located in the desired
organ or tissue with the aid of a magnetic field gradient created by an implanted
magnet. In addition, it has been shown that the nanoparticle coating can adsorb and
desorb a chemotherapeutic agent, so they can be used for magnetically driven drug
delivery [35]. These experiments suggest that nanoparticles could also be utilized
in planta, as magnetic carriers of phytosanitary agents, nutrients, enzymes, nucleic
305
in the applications just mentioned. In addition, the capability of magnetic nanoparticles to interact with a magnetic field increases the possibilities for their exploitation.
For instance, in the same way as nanoparticles can act as vehicles for magnetically targeted drug delivery in chemotherapy against cancer [34, 35] they could be
implemented in phytosanitary treatments, for the selective and controlled delivery of
agrochemicals or other biomolecules, or to induce genetic transformations etc. [13].
Also in the analogy with biomedical applications, magnetic nanoparticles could play
a role as MRI contrast agents for plant research. In fact this technique is as well suitable for studying the health of a plant in a non-destructive way [36], and has made
possible the study of the modifications of the biophysical parameters of a cucumber
plant as response to environmental changes [37], the changes in the dynamics of the
sap flow [38], or the damage induced by plant parasitic nematodes and soil borne
pathogens on sugar beet plants [39]. Even the localized heating by magnetic hyperthermia [40] might be as well a useful treatment in agriculture and agronomy. As
suggested by Pérez de Luque and Rubiales [13], it might be applied to eliminate
parasitic weeds, assuming that nanoparticles are able to accumulate in a specific
plant organ. This could be the case, for example, of tubercles in Orobanche crenata,
where the nanoparticles (administered for example by the roots) would accumulate
due to their sink effect.
As is well known, magnetic nanoparticles can be coated with biocompatible materials as silica [41, 42], dextran [43], polyvinyl alcohol (PVA) [44], poly(ethylene
glycol) (PEG) [45] etc., which allows modifying the particle surface with a large
number of molecules of biological interest, and therefore broadening the functionality of the nanoparticle. The coating can be functionalized with bio-molecules, as
for instance antibodies [46, 47], able to recognize a specific pathogen in a culture or
soil, making the nanoparticle act as a magnetic label for the pathogen to be detected
by a biosensor [17, 18, 48]. The diversity of materials that can be used as coating
and the wide variety of functionalization protocols make the magnetic nanoparticles
very promising tools for plant biology and biotechnology.
In the following sections we will deal with two types of core-shell magnetic
nanoparticles. In the first case, they consist of an iron core coated with
graphite/graphene layers; from here on they will be called carbon-coated
(Fe@C) nanoparticles. The second type is magnetite coated with silica (i.e.,
Fe 3 O 4 @SiO 2 ) nanoparticles; this coating, besides being biocompatible, stable and
suitable for the encapsulation of biomolecules, [49] is very easy to be functionalized
with biological moieties [46]. Likewise, the biocompatibility of the Fe@C nanoparticles has been successfully tested in in vitro and in vivo animal models [35, 50,
51]. In particular, the experiments carried out in New Zeeland rabbits have shown
that these nanoparticles, once injected into the animal, can be located in the desired
organ or tissue with the aid of a magnetic field gradient created by an implanted
magnet. In addition, it has been shown that the nanoparticle coating can adsorb and
desorb a chemotherapeutic agent, so they can be used for magnetically driven drug
delivery [35]. These experiments suggest that nanoparticles could also be utilized
in planta, as magnetic carriers of phytosanitary agents, nutrients, enzymes, nucleic