1 3
Topics in Current Chemistry (2020) 378:40
shown to lead to phase transformation with better crystallinity, although decreasing
their reducibility [202].The scalability issue has also been answered by using a 30-l
reactor, although there is only one report of such nature [203].
Plants or plants extracts have been used for the synthesis of nanoparticles [204].
Most recently, IONPs have been synthesized using figs, Ficuscarica and Plantago
major extracts, which, apart from reducing precursors, also cap and stabilize the particles. These reactions have been concluded to take place due to the presence of phenols,
and normally lead to sizes ranging from 2 to 50 nm [205, 206].
The main advantages of this method are that it is energy saving and non-toxic. Also,
there is an unlimited supply of reducing agents, making it economically viable. On
the other hand, its major disadvantage is unpredictability regarding the nature of the
particles, with less control over the shape and size, along with uncertainty of yielding
monodisperse particles when scaled up.
2.11 Other Methods
Several different methods for the synthesis of IONPs have not been described above
due to a dearth of information in the literature. Alvarez et al. [207] developed a novel
flow injection synthesis (FIS) method to fabricate magnetite nanoparticles in a capillary reactor, and produced homogenous particles of 2–7 nm with high reproducibility.
There have been reports of the use of metal rods as anodes and electrochemical deposition in the presence of surfactants to yield 3–8 nm particles [208–210]. Chemical vapor
deposition (CVD) [211, 212] has been used to fabricate thin films and morphologycontrolled nanoparticles. Other methods, such as synthesis in a reactor [213], the solution combustion method [214], and the use of microfluidic channels on a chip [215,
216], have also been introduced.
All the methods described above have their own pros and cons, and the choice of
one or the other depends on the application for which the nanoparticles are being developed. Thus, for nanoparticles to be used as MRI CAs, the most suitable methods appear
to be the thermal decomposition or microwave methods, since they provide a very narrow size distribution, high saturation magnetization and good morphology control.
3 Functionalization of IONPs
One of the most important topics in the design of IONPs for in vivo applications is
functionalization, which provides NPs with high stability in physiological media,
stealth and vector targeting properties. In this section, we summarize the most relevant
methods to functionalize IONPs for clinical purposes.
3.1 Organic Supra‑structures
In recent decades, a class of highly branched and monodispersed macromolecules
with well-defined three-dimensional (3D) architectures, such as nanomicelles,
63
Reprinted from the journal
Topics in Current Chemistry (2020) 378:40
shown to lead to phase transformation with better crystallinity, although decreasing
their reducibility [202].The scalability issue has also been answered by using a 30-l
reactor, although there is only one report of such nature [203].
Plants or plants extracts have been used for the synthesis of nanoparticles [204].
Most recently, IONPs have been synthesized using figs, Ficuscarica and Plantago
major extracts, which, apart from reducing precursors, also cap and stabilize the particles. These reactions have been concluded to take place due to the presence of phenols,
and normally lead to sizes ranging from 2 to 50 nm [205, 206].
The main advantages of this method are that it is energy saving and non-toxic. Also,
there is an unlimited supply of reducing agents, making it economically viable. On
the other hand, its major disadvantage is unpredictability regarding the nature of the
particles, with less control over the shape and size, along with uncertainty of yielding
monodisperse particles when scaled up.
2.11 Other Methods
Several different methods for the synthesis of IONPs have not been described above
due to a dearth of information in the literature. Alvarez et al. [207] developed a novel
flow injection synthesis (FIS) method to fabricate magnetite nanoparticles in a capillary reactor, and produced homogenous particles of 2–7 nm with high reproducibility.
There have been reports of the use of metal rods as anodes and electrochemical deposition in the presence of surfactants to yield 3–8 nm particles [208–210]. Chemical vapor
deposition (CVD) [211, 212] has been used to fabricate thin films and morphologycontrolled nanoparticles. Other methods, such as synthesis in a reactor [213], the solution combustion method [214], and the use of microfluidic channels on a chip [215,
216], have also been introduced.
All the methods described above have their own pros and cons, and the choice of
one or the other depends on the application for which the nanoparticles are being developed. Thus, for nanoparticles to be used as MRI CAs, the most suitable methods appear
to be the thermal decomposition or microwave methods, since they provide a very narrow size distribution, high saturation magnetization and good morphology control.
3 Functionalization of IONPs
One of the most important topics in the design of IONPs for in vivo applications is
functionalization, which provides NPs with high stability in physiological media,
stealth and vector targeting properties. In this section, we summarize the most relevant
methods to functionalize IONPs for clinical purposes.
3.1 Organic Supra‑structures
In recent decades, a class of highly branched and monodispersed macromolecules
with well-defined three-dimensional (3D) architectures, such as nanomicelles,
63
Reprinted from the journal