of conversion based on host-guest chemistry, which demonstrates that biological
stimuli could be used to achieve sophisticated biomedical applications.
Lee et al. reported the use of CD-based self-assembled magnetic nanoparticles as
DDSs for in vivo cancer treatment [38]. Supramolecular nanoparticles were composed of doxorubicin and four different molecular building blocks, including
adamantane-grafted polyamidoamine dendrimers (Ad-PAMAM), β-CD-grafted
branched polyethylenimine (CD-PEI), Ad-functionalized polyethylene glycol
(Ad-PEG), and 6 nm Ad-grafted Zn 0.4 Fe 2.6 O 4 superparamagnetic nanoparticles
(Ad-MNP) (Fig. 19). Nanoparticle size was fine-tuned to be 70 nm, 100 nm, or
160 nm. The enhanced permeation and retention (EPR) effects were expected to
drive preferential tumor accumulation of nanoparticles. The embedded Ad-MNP
served as a built-in transformer that converted radiofrequency external alternative
magnetic field (AMF) into heat, allowing for stimuli-responsive drug release from
supramolecular nanoparticles. In vitro drug release confirmed that AMF could
trigger the rapid release of doxorubicin from supramolecular nanoparticles with a
size of 70 nm, which resulted in a drop in cell viability. In vivo therapeutic efficacy
was evaluated by using tumor-bearing mouse model. Supramolecular nanoparticles
of 70 nm were administrated to DLD-1 xenografted mice by intravenous injection,
followed by AMF treatment after 36 h postinjection. It was discovered that mouse
groups treated with supramolecular nanoparticles and AMF had significant suppression on tumor growth. Therefore, host-guest chemistry is an efficient strategy to
design and assemble supramolecular nanoparticles for targeted drug delivery. Supramolecular nanoparticles are advantageous for the reason that complex DDS could be
conveniently assembled and dissociate on demand to release cargo. Supramolecular
strategy for DDS design could be used to fulfil the increasing complexity of drug
delivery applications.
23.4.3 Hydrogel Biomaterials
Hydrogel biomaterials are implantable materials, which could be used to encapsulate
pharmaceutical drugs and bioactive agents. Hydrogels often hold large quantity of
water via surface tension or capillary effect. These materials could be highly
biocompatible and used for drug delivery or cell/tissue engineering. There are two
major types of hydrogel biomaterials based on host-guest chemistry: (1) poly
(pseudo)rotaxanes by threading macrocyclic molecules onto polymer chains and
(2) macrocyclic host molecules and guest molecules both conjugated onto polymers
as the side chains. By incorporating stimuli-responsive moieties, dynamic nature of
host-guest interaction renders hydrogel biomaterials to respond to physical or
ä
Fig. 17 (continued) contents contained. (c) Simultaneous excitation with 448 nm light AND
addition of NaOH causes the contents to be released. (Adapted with permission from Ref.
[36]. Copyright 2009 American Chemical Society)
23 Stimuli-Responsive Self-Assembly Based on Macrocyclic Hosts and Biomedical. . .
629
stimuli could be used to achieve sophisticated biomedical applications.
Lee et al. reported the use of CD-based self-assembled magnetic nanoparticles as
DDSs for in vivo cancer treatment [38]. Supramolecular nanoparticles were composed of doxorubicin and four different molecular building blocks, including
adamantane-grafted polyamidoamine dendrimers (Ad-PAMAM), β-CD-grafted
branched polyethylenimine (CD-PEI), Ad-functionalized polyethylene glycol
(Ad-PEG), and 6 nm Ad-grafted Zn 0.4 Fe 2.6 O 4 superparamagnetic nanoparticles
(Ad-MNP) (Fig. 19). Nanoparticle size was fine-tuned to be 70 nm, 100 nm, or
160 nm. The enhanced permeation and retention (EPR) effects were expected to
drive preferential tumor accumulation of nanoparticles. The embedded Ad-MNP
served as a built-in transformer that converted radiofrequency external alternative
magnetic field (AMF) into heat, allowing for stimuli-responsive drug release from
supramolecular nanoparticles. In vitro drug release confirmed that AMF could
trigger the rapid release of doxorubicin from supramolecular nanoparticles with a
size of 70 nm, which resulted in a drop in cell viability. In vivo therapeutic efficacy
was evaluated by using tumor-bearing mouse model. Supramolecular nanoparticles
of 70 nm were administrated to DLD-1 xenografted mice by intravenous injection,
followed by AMF treatment after 36 h postinjection. It was discovered that mouse
groups treated with supramolecular nanoparticles and AMF had significant suppression on tumor growth. Therefore, host-guest chemistry is an efficient strategy to
design and assemble supramolecular nanoparticles for targeted drug delivery. Supramolecular nanoparticles are advantageous for the reason that complex DDS could be
conveniently assembled and dissociate on demand to release cargo. Supramolecular
strategy for DDS design could be used to fulfil the increasing complexity of drug
delivery applications.
23.4.3 Hydrogel Biomaterials
Hydrogel biomaterials are implantable materials, which could be used to encapsulate
pharmaceutical drugs and bioactive agents. Hydrogels often hold large quantity of
water via surface tension or capillary effect. These materials could be highly
biocompatible and used for drug delivery or cell/tissue engineering. There are two
major types of hydrogel biomaterials based on host-guest chemistry: (1) poly
(pseudo)rotaxanes by threading macrocyclic molecules onto polymer chains and
(2) macrocyclic host molecules and guest molecules both conjugated onto polymers
as the side chains. By incorporating stimuli-responsive moieties, dynamic nature of
host-guest interaction renders hydrogel biomaterials to respond to physical or
ä
Fig. 17 (continued) contents contained. (c) Simultaneous excitation with 448 nm light AND
addition of NaOH causes the contents to be released. (Adapted with permission from Ref.
[36]. Copyright 2009 American Chemical Society)
23 Stimuli-Responsive Self-Assembly Based on Macrocyclic Hosts and Biomedical. . .
629