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could be emulsion polymerization, which is a two-stage process that lies in the production of monodisperse seeds and then coating them with a MIP shell (Poma et al.
2010). Some authors have studied the mechanism and factors that can influence this
method. In this regard, Zhang et al. (2014) studied the correlation between the shell
thickness and binding capacity of MIP for core-shell particles prepared by emulsion
polymerization. Apart from this, other methods for synthesizing core-shell particles
have also been tested. In this light, Wang et al. (2018) developed magnetic mesoporous MIPs by precipitation polymerization combined with surface imprinting on the
surface of Fe 3 O 4 NPs. This material showed fast binding affinity, excellent magnetic
response and remarkable specificity (Wang et al. 2018).
MIP grafting onto preformed beads have also proven to be a useful tool for coreshell technology. This allows the growth of thin films imprinted onto the surface of
preformed materials, such as silica, with a predetermined morphology. For this purpose, the ‘grafting to’ or the ‘grafting from’ approaches can be used. Although FRP
has traditionally been used in the grafting process, the use of controlled living radical polymerization is increasing remarkably in recent years, which has favored the
control of polymer architectures, and therefore, particle sizes (Niu et al. 2016). With
respect to the ‘grafting to’ approach, a MIP polymer can be chemically bound to a
surface as long as the surface has a functional group capable of chemically binding
to the MIP. This approach allows not only for grafting preformed polymers on solid
surfaces, but also directly synthesize new polymers on those surfaces. For the latter,
the solid support must be derivatized with polymerizable acrylic/vinyl groups on its
surface, which then react with free radicals and monomers in solution. Despite its
potential benefits, the synthesis of thin layers imprinted by the grafting approach is
not a simple goal due to difficulties in controlling film thickness. In addition, grafting density is limited by kinetic and steric factors.
To overcome the above-mentioned drawbacks, most of the time, monomers are
polymerized directly from initiators previously attached to the surface of the solid
support, a strategy known as the ‘grafting from’ approach. The resulting MIP composites have greater accessibility to the binding site, and therefore, faster mass
transfer. Very often, dithiocarbamate iniferters are used for MIP development by
surface-initiated living-radical polymerization (Perez-Moral and Mayes 2007).
Gutierrez-Climente et al. (2016) also developed a core-shell material imprinted onto
preformed silica which showed a high capacity for the resolution of enantiomers,
and was thus used as a chiral stationary phase in liquid chromatography.
In order to improve the efficiency and mass transfer rates of imprinted core-shell
materials, some authors have carried out the polymerization using thiol-ene click
chemistry (Huang et al. 2018; Wang et al. 2019). Xu and Ye (2011) deepened the use
of Cu(I)-catalyzed click chemistry for immobilizing or modifying core-shell NPs.
The clickable MIP NPs were made of an imprinted core surrounded by a loosely
cross-linked shell, which did not hinder the analyte diffusion (Xu and Ye 2011).
The core-shell approach has also been combined with the solid-phase synthesis
of imprinted polymers, using MIP as cores. In this regard, Moczko et al. (2013)
reported a methodology to produce core MIP NPs (MIN), which were then
superficially modified with different polymers grafted on it. They presented a way
for developing core-shell nanomaterials for selective molecular recognition, being
5 Plastic Receptors Developed by Imprinting Technology as Smart Polymers Imitating…
could be emulsion polymerization, which is a two-stage process that lies in the production of monodisperse seeds and then coating them with a MIP shell (Poma et al.
2010). Some authors have studied the mechanism and factors that can influence this
method. In this regard, Zhang et al. (2014) studied the correlation between the shell
thickness and binding capacity of MIP for core-shell particles prepared by emulsion
polymerization. Apart from this, other methods for synthesizing core-shell particles
have also been tested. In this light, Wang et al. (2018) developed magnetic mesoporous MIPs by precipitation polymerization combined with surface imprinting on the
surface of Fe 3 O 4 NPs. This material showed fast binding affinity, excellent magnetic
response and remarkable specificity (Wang et al. 2018).
MIP grafting onto preformed beads have also proven to be a useful tool for coreshell technology. This allows the growth of thin films imprinted onto the surface of
preformed materials, such as silica, with a predetermined morphology. For this purpose, the ‘grafting to’ or the ‘grafting from’ approaches can be used. Although FRP
has traditionally been used in the grafting process, the use of controlled living radical polymerization is increasing remarkably in recent years, which has favored the
control of polymer architectures, and therefore, particle sizes (Niu et al. 2016). With
respect to the ‘grafting to’ approach, a MIP polymer can be chemically bound to a
surface as long as the surface has a functional group capable of chemically binding
to the MIP. This approach allows not only for grafting preformed polymers on solid
surfaces, but also directly synthesize new polymers on those surfaces. For the latter,
the solid support must be derivatized with polymerizable acrylic/vinyl groups on its
surface, which then react with free radicals and monomers in solution. Despite its
potential benefits, the synthesis of thin layers imprinted by the grafting approach is
not a simple goal due to difficulties in controlling film thickness. In addition, grafting density is limited by kinetic and steric factors.
To overcome the above-mentioned drawbacks, most of the time, monomers are
polymerized directly from initiators previously attached to the surface of the solid
support, a strategy known as the ‘grafting from’ approach. The resulting MIP composites have greater accessibility to the binding site, and therefore, faster mass
transfer. Very often, dithiocarbamate iniferters are used for MIP development by
surface-initiated living-radical polymerization (Perez-Moral and Mayes 2007).
Gutierrez-Climente et al. (2016) also developed a core-shell material imprinted onto
preformed silica which showed a high capacity for the resolution of enantiomers,
and was thus used as a chiral stationary phase in liquid chromatography.
In order to improve the efficiency and mass transfer rates of imprinted core-shell
materials, some authors have carried out the polymerization using thiol-ene click
chemistry (Huang et al. 2018; Wang et al. 2019). Xu and Ye (2011) deepened the use
of Cu(I)-catalyzed click chemistry for immobilizing or modifying core-shell NPs.
The clickable MIP NPs were made of an imprinted core surrounded by a loosely
cross-linked shell, which did not hinder the analyte diffusion (Xu and Ye 2011).
The core-shell approach has also been combined with the solid-phase synthesis
of imprinted polymers, using MIP as cores. In this regard, Moczko et al. (2013)
reported a methodology to produce core MIP NPs (MIN), which were then
superficially modified with different polymers grafted on it. They presented a way
for developing core-shell nanomaterials for selective molecular recognition, being
5 Plastic Receptors Developed by Imprinting Technology as Smart Polymers Imitating…