FC12+Br– through an optical transmittance experiment. At the beginning, simple
inclusion complexes of SCAD and FC12+Br– formed driven by the hydrophobic
and electrostatic interactions. The additional FC12+Br– molecules readily co-assembled with these complexes through electrostatic interactions and grew into binary
nanoparticles. From the TEM images, a spherical morphology with an average
diameter of 180 nm was observed, which is consistent with the DLS results. The
SACD/FC nanoparticles also possessed a zeta potential as –77.67 mV, indicating
that the electrostatic interaction played an important role to keep the stability of the
non-covalent aggregates. Interestingly, the SACD/FC nanoparticles disassembled at
pH 4.0 due to the protonation of carboxylic group of SACD. Meanwhile, the SACD/
FC nanoparticles reassembled at pH 7.5. Finally, doxorubicin hydrochloride (DOX)
was chosen as model drug to investigate the drug-loading efficiency and acidresponsive release of the SACD/FC nanoparticles. The release rate greatly increased
under acid conditions at pH 4.0 and 6.5. More than 90% of DOX were released at pH
4.0 within 150 min. The efficient cargo release property of the SACD/FC nanoparticles under acidic condition accords with the intrinsic acidic environment of
tumor cells, which made this supramolecular assembly formed by multi-charged
cyclodextrin-induced aggregation a specific site release drug delivery candidate.
21.3 Supramolecular Assembly Constructed from Polycationic
Cyclodextrin-Induced Aggregation
The molecular-induced aggregation behaviors of polycationic β-cyclodextrin toward
three anionic surfactants with different hydrophobic tails in length were investigated
(Fig. 7) [29]. The critical aggregation concentrations (CACs) of the three surfactants
were 39.9 mmolÁL
À1 for sodium decyl sulfonate (SDES), 20 mmolÁL
À1 for sodium
undecyl sulfonate (SUS), and 9.7 mmolÁL
À1 for sodium dodecyl sulfate (SDS). With
the addition of polycationic β-cyclodextrin, the CAC values of the three surfactants
sharply decreased by a factor of 14–467. The preferable mixing ratio between the
polycationic β-cyclodextrin and the surfactants was 1:7 measured by the optical
transmittance experiments. All of the aggregates possessed a spherical morphology
with a diameter of 200–400 nm in the TEM images, which was further confirmed by
the DLS experiment. Furthermore, the aggregates formed by β-cyclodextrin with
SLS and SDBS possessed a moderate positive zeta potential and were selected to
study the guest encapsulation ability.
Another polycationic β-cyclodextrin-induced aggregation supramolecular assemblies were constructed with seven ethyl imidazolium-acetyl pendants (EICD) and
hyaluronans (Fig. 8) [30]. Hyaluronidase (HAase)-hyaluronan (HA) pair attracted
great attention because hyaluronan acceptors are overexpressed on the surface of
cancer cells and hyaluronidase plays an important role in the movement of cancer
cells to degrade hyaluronan [31, 32]. The critical aggregation concentration (CAC)
of HA was 15 μM, while the EICD-induced CAC value was 11 μM. The diameter
value of the EICD-induced assembly was 630 nm from dynamic light scattering
(DLS) experiment, and this value was further confirmed by images of confocal laser
21 Supramolecular Assembly Constructed from Multi-charged Cyclodextrin. . .
581
inclusion complexes of SCAD and FC12+Br– formed driven by the hydrophobic
and electrostatic interactions. The additional FC12+Br– molecules readily co-assembled with these complexes through electrostatic interactions and grew into binary
nanoparticles. From the TEM images, a spherical morphology with an average
diameter of 180 nm was observed, which is consistent with the DLS results. The
SACD/FC nanoparticles also possessed a zeta potential as –77.67 mV, indicating
that the electrostatic interaction played an important role to keep the stability of the
non-covalent aggregates. Interestingly, the SACD/FC nanoparticles disassembled at
pH 4.0 due to the protonation of carboxylic group of SACD. Meanwhile, the SACD/
FC nanoparticles reassembled at pH 7.5. Finally, doxorubicin hydrochloride (DOX)
was chosen as model drug to investigate the drug-loading efficiency and acidresponsive release of the SACD/FC nanoparticles. The release rate greatly increased
under acid conditions at pH 4.0 and 6.5. More than 90% of DOX were released at pH
4.0 within 150 min. The efficient cargo release property of the SACD/FC nanoparticles under acidic condition accords with the intrinsic acidic environment of
tumor cells, which made this supramolecular assembly formed by multi-charged
cyclodextrin-induced aggregation a specific site release drug delivery candidate.
21.3 Supramolecular Assembly Constructed from Polycationic
Cyclodextrin-Induced Aggregation
The molecular-induced aggregation behaviors of polycationic β-cyclodextrin toward
three anionic surfactants with different hydrophobic tails in length were investigated
(Fig. 7) [29]. The critical aggregation concentrations (CACs) of the three surfactants
were 39.9 mmolÁL
À1 for sodium decyl sulfonate (SDES), 20 mmolÁL
À1 for sodium
undecyl sulfonate (SUS), and 9.7 mmolÁL
À1 for sodium dodecyl sulfate (SDS). With
the addition of polycationic β-cyclodextrin, the CAC values of the three surfactants
sharply decreased by a factor of 14–467. The preferable mixing ratio between the
polycationic β-cyclodextrin and the surfactants was 1:7 measured by the optical
transmittance experiments. All of the aggregates possessed a spherical morphology
with a diameter of 200–400 nm in the TEM images, which was further confirmed by
the DLS experiment. Furthermore, the aggregates formed by β-cyclodextrin with
SLS and SDBS possessed a moderate positive zeta potential and were selected to
study the guest encapsulation ability.
Another polycationic β-cyclodextrin-induced aggregation supramolecular assemblies were constructed with seven ethyl imidazolium-acetyl pendants (EICD) and
hyaluronans (Fig. 8) [30]. Hyaluronidase (HAase)-hyaluronan (HA) pair attracted
great attention because hyaluronan acceptors are overexpressed on the surface of
cancer cells and hyaluronidase plays an important role in the movement of cancer
cells to degrade hyaluronan [31, 32]. The critical aggregation concentration (CAC)
of HA was 15 μM, while the EICD-induced CAC value was 11 μM. The diameter
value of the EICD-induced assembly was 630 nm from dynamic light scattering
(DLS) experiment, and this value was further confirmed by images of confocal laser
21 Supramolecular Assembly Constructed from Multi-charged Cyclodextrin. . .
581