Topics in Current Chemistry (2020) 378:13
1 3
be adsorbed onto the surface of the IONPs via coordination of carboxylate functionalities, thereby exposing new terminal groups for further modification [73]. The
post-synthesis protocols are always divided into two steps: the first step consists of
IONPs synthesis, followed by surface modification as a separate step. Such techniques are performed mainly via ligand addition or exchange and encapsulation
using polymeric matrixes [74]. One advantage of these methodologies is the possibility to design multiple nanostructures using either one protocol or another as well
as a combination of both.
Some examples of magnetic platforms based on IONPs for the conjugation of
DNA are given in Table 1. The synthesis and coating methods are also presented,
showing the diversity of strategies used for obtaining functional conjugates.
3 Interaction of DNA–Magnetic Nanoparticles: Preparation
of Nanoplatforms
DNA molecules play an important role in transferring genetic information through
generations. Such structures consist of several nucleosides sharing a phosphate
backbone with sequences generated from assemblies of bases able to form a double
helix structure [84]. Due to its programmability, cost-effectiveness, ease of modification, and the ability to recognize a broad range of analytes, DNA is a highly
attractive molecule for use in designing hybrid materials [85]. Such features together
with the extraordinary properties of MNPs allow the fabrication of nanoplatforms
as powerful molecular recognition tools and targeted drug delivery carriers [86, 87].
Nanoplatform design depends on the type of interaction between DNA and the
nanoparticle surface. Since a large number of coupling agents are commercially
available, the covalent immobilization of nucleic acids, as well as of other biomolecules, is easy to achieve (Fig. 3). Such methodologies include traditional methods
of bioconjugation and the ‘click’-chemistry approaches, such as carbodiimide activation, thiol-disulfide exchange, aldehyde-amine condensation, and azide-alkyne
cycloaddition [88, 89]. Covalent immobilization is also attained with thiolated and
aminated molecules [90]. To this end, amino, sulfhydryl, carboxyl, and azido groups
are initially formed on the surface of the nanoparticles. Although all of these methodologies are well described, some key parameters need to be considered, such as
biomolecule orientation and the specific activity [17].
The covalent immobilization of DNA onto the surface of MNPs is not the only
interaction of such biocomposites, but it is certainly considered to be a very useful alternative for in vitro diagnosis [24]. However, different methods are often
employed to achieve bioconjugation, such as physical adsorption, Van der Waals,
electrostatic or high-affinity noncovalent interactions [25–27]. Knowledge of the relevant adsorption mechanisms provides valuable information in terms of nanomaterial surface design with the aim to manipulate or suppress highly specific binding
and to control bonds between the components of the biocomposites [17]. For example, the use of an electrostatic approach could have advantages in terms of time and
resources, but a high-affinity methodology could be more specific.
24
Reprinted from the journal
1 3
be adsorbed onto the surface of the IONPs via coordination of carboxylate functionalities, thereby exposing new terminal groups for further modification [73]. The
post-synthesis protocols are always divided into two steps: the first step consists of
IONPs synthesis, followed by surface modification as a separate step. Such techniques are performed mainly via ligand addition or exchange and encapsulation
using polymeric matrixes [74]. One advantage of these methodologies is the possibility to design multiple nanostructures using either one protocol or another as well
as a combination of both.
Some examples of magnetic platforms based on IONPs for the conjugation of
DNA are given in Table 1. The synthesis and coating methods are also presented,
showing the diversity of strategies used for obtaining functional conjugates.
3 Interaction of DNA–Magnetic Nanoparticles: Preparation
of Nanoplatforms
DNA molecules play an important role in transferring genetic information through
generations. Such structures consist of several nucleosides sharing a phosphate
backbone with sequences generated from assemblies of bases able to form a double
helix structure [84]. Due to its programmability, cost-effectiveness, ease of modification, and the ability to recognize a broad range of analytes, DNA is a highly
attractive molecule for use in designing hybrid materials [85]. Such features together
with the extraordinary properties of MNPs allow the fabrication of nanoplatforms
as powerful molecular recognition tools and targeted drug delivery carriers [86, 87].
Nanoplatform design depends on the type of interaction between DNA and the
nanoparticle surface. Since a large number of coupling agents are commercially
available, the covalent immobilization of nucleic acids, as well as of other biomolecules, is easy to achieve (Fig. 3). Such methodologies include traditional methods
of bioconjugation and the ‘click’-chemistry approaches, such as carbodiimide activation, thiol-disulfide exchange, aldehyde-amine condensation, and azide-alkyne
cycloaddition [88, 89]. Covalent immobilization is also attained with thiolated and
aminated molecules [90]. To this end, amino, sulfhydryl, carboxyl, and azido groups
are initially formed on the surface of the nanoparticles. Although all of these methodologies are well described, some key parameters need to be considered, such as
biomolecule orientation and the specific activity [17].
The covalent immobilization of DNA onto the surface of MNPs is not the only
interaction of such biocomposites, but it is certainly considered to be a very useful alternative for in vitro diagnosis [24]. However, different methods are often
employed to achieve bioconjugation, such as physical adsorption, Van der Waals,
electrostatic or high-affinity noncovalent interactions [25–27]. Knowledge of the relevant adsorption mechanisms provides valuable information in terms of nanomaterial surface design with the aim to manipulate or suppress highly specific binding
and to control bonds between the components of the biocomposites [17]. For example, the use of an electrostatic approach could have advantages in terms of time and
resources, but a high-affinity methodology could be more specific.
24
Reprinted from the journal