292
continues, molecular imprinted cyclodextrin polymers also arrived in this field. As in
the previous example, the determination of dyes in food is in order. For instance,
monomeric cyclodextrin reacts with maleic acid, and then, in presence of a template,
such as Congo red, the polymerization takes place with N,N′-methylenebisacrylamide
as the cross-linker (Liu et al. 2015). Thanks to this type of synthesis procedures, the
molecular imprinted cyclodextrin polymer shows a high selectivity and a remarkable
sorption power for its target. Also in recent years, cyclodextrin polymers have been
prepared with some especial characteristics. A few examples are a cyclodextrin polymer with a higher specific area (Li et al. 2018), grafted onto metallic graphene (Li
et al. 2016a), added to ionic liquids (Feng et al. 2015), or imprinted on carbon nanotubes (Liang et al. 2019). Many of these new materials are designed in order to be
used in solid-phase extractions, and the main interests are their capabilities for the
removal and/or the determination of organic molecules present in food.
Among their many possible applications, cyclodextrin monomers are also common for food packaging, and they began to be exploited for that purpose since the
end of the past century (Szente and Fenyvesi 2018). In those first uses, cyclodextrins
are present in a polymer network but without being cross-linked to it. The first
reported use of a cyclodextrin polymer in packaging dates back from a decade ago.
At that time, β-cyclodextrin and polyvinyl alcohol were cross-linked with glyoxal,
following different procedures, to remove an undesirable product in food such as
cholesterol (López-De-Dicastillo et al. 2011).
On the other hand, active films are designed to liberate chemicals encapsulated in
them. In this case, cyclodextrin units are, for instance, grafted onto a modified polyamide, both by a non-covalent and a covalent cross-linking; in the presence of a
template, two different synthetic polymers mixed produced a film capable to release
chemicals using UV stimuli (Tan et al. 2016). One of the most sought characteristics
for a packaging film is its antibacterial power. In order to achieve this potential, it is
also feasible to integrate ZnO nanoparticles into polymer films (Andrade-Del Olmo
et al. 2019). In this investigation, anionic cyclodextrin is added with chitosan layer
by layer onto a poly-L-lactic acid-ZnO film to provide it the antibacterial ZnO properties but also with the ability to release carvacrol, plus the hydrophobicity from
poly-L-lactic acid and the biodegradability provided by all the polymeric components. Another path to create an antibacterial film is to cross-link a sorbate/cyclodextrin complex, such that with sodium benzoate (Yang et al. 2019). By a green synthesis
procedure, xylan, hydroxyethyl cellulose, and the complexed cyclodextrin molecules
are cross-linked using citric acid. The resulting film possesses the desired mechanical properties, besides a low oxygen permeability and good antibacterial properties.
6.3.2 Cyclodextrin Polymers in Drug Delivery
The first reviewing of the potential applications of cyclodextrin polymers in the pharmaceutical industry was written by Fenyvesi (1988), and it was mainly based on cyclodextrin cross-linked with epichlorohydrin. The soluble cyclodextrin- epichlorohydrin
M. Petitjean et al.
continues, molecular imprinted cyclodextrin polymers also arrived in this field. As in
the previous example, the determination of dyes in food is in order. For instance,
monomeric cyclodextrin reacts with maleic acid, and then, in presence of a template,
such as Congo red, the polymerization takes place with N,N′-methylenebisacrylamide
as the cross-linker (Liu et al. 2015). Thanks to this type of synthesis procedures, the
molecular imprinted cyclodextrin polymer shows a high selectivity and a remarkable
sorption power for its target. Also in recent years, cyclodextrin polymers have been
prepared with some especial characteristics. A few examples are a cyclodextrin polymer with a higher specific area (Li et al. 2018), grafted onto metallic graphene (Li
et al. 2016a), added to ionic liquids (Feng et al. 2015), or imprinted on carbon nanotubes (Liang et al. 2019). Many of these new materials are designed in order to be
used in solid-phase extractions, and the main interests are their capabilities for the
removal and/or the determination of organic molecules present in food.
Among their many possible applications, cyclodextrin monomers are also common for food packaging, and they began to be exploited for that purpose since the
end of the past century (Szente and Fenyvesi 2018). In those first uses, cyclodextrins
are present in a polymer network but without being cross-linked to it. The first
reported use of a cyclodextrin polymer in packaging dates back from a decade ago.
At that time, β-cyclodextrin and polyvinyl alcohol were cross-linked with glyoxal,
following different procedures, to remove an undesirable product in food such as
cholesterol (López-De-Dicastillo et al. 2011).
On the other hand, active films are designed to liberate chemicals encapsulated in
them. In this case, cyclodextrin units are, for instance, grafted onto a modified polyamide, both by a non-covalent and a covalent cross-linking; in the presence of a
template, two different synthetic polymers mixed produced a film capable to release
chemicals using UV stimuli (Tan et al. 2016). One of the most sought characteristics
for a packaging film is its antibacterial power. In order to achieve this potential, it is
also feasible to integrate ZnO nanoparticles into polymer films (Andrade-Del Olmo
et al. 2019). In this investigation, anionic cyclodextrin is added with chitosan layer
by layer onto a poly-L-lactic acid-ZnO film to provide it the antibacterial ZnO properties but also with the ability to release carvacrol, plus the hydrophobicity from
poly-L-lactic acid and the biodegradability provided by all the polymeric components. Another path to create an antibacterial film is to cross-link a sorbate/cyclodextrin complex, such that with sodium benzoate (Yang et al. 2019). By a green synthesis
procedure, xylan, hydroxyethyl cellulose, and the complexed cyclodextrin molecules
are cross-linked using citric acid. The resulting film possesses the desired mechanical properties, besides a low oxygen permeability and good antibacterial properties.
6.3.2 Cyclodextrin Polymers in Drug Delivery
The first reviewing of the potential applications of cyclodextrin polymers in the pharmaceutical industry was written by Fenyvesi (1988), and it was mainly based on cyclodextrin cross-linked with epichlorohydrin. The soluble cyclodextrin- epichlorohydrin
M. Petitjean et al.