MitP) by the glutaraldehyde-mediated cross-linking reaction, obtaining MitP-MNPs
that possess mitochondrion-targeting ability. Owing to numerous cyclohexylalanine
pendants located around the core of MitP-MNPs, and abundant β-CD on the HACD
polymer, large-sized supramolecular assembly may be further achieved through the
hierarchically intermolecular organization. When HACD was added, a strong multivalent binding between the hydrophobic cyclohexyl group of MitP and β-CD’s
cavity induced the formation of the supramolecular nanofibers with 100–500 nm in
diameter and several micrometers in length.
Interestingly, the constructed one-dimensional supramolecular magnetic nanofibers could sensitively respond to various magnetic fields. This assembling process
has two critical properties: (1) the assembling direction of the nanofibers is strictly
along with the magnetic field. When the components were under the geomagnetic
field, the nanofibers could be gradually induced along with the direction of this field,
just like a campus; when treated by the artificial strong field, the nanofibers could be
formed along with the direction of this field. (2) The assembling rate of the
nanofibers is in proportion with the strength of magnetic field. Moreover, the
formation of nanofibers could also be regulated by light irradiation in the presence
of the photo-responsive molecule arylazopyrazoles carboxylate (AAP) as the competitive guest. Under the green light irradiation, AAP was transformed into transAAP, disrupting the assembling process of this nanofibers; under the UV irradiation,
trans-AAP is transformed into cis-AAP, and the nanofibers could be formed.
20.3.3 Two-Dimensional Magnetic Supramolecular Nanoassemblies
By using modified magnetic nanoparticles, two-dimensional magnetic supramolecular
nanostructures could be achieved on proper substrates or interfaces. In an early study,
Sun et al. realized polymer-mediated self-assembly of magnetic FePt nanoparticles to
form two-dimensional nanofilms. The magnetic FePt nanoparticles were firstly modified by the functional polymers poly(vinylpyrrolidone) (PVP) or poly(ethylenimine)
(PEI), followed by self-assembling on PEI-modified silicon oxide surface, generating
wide-range and uniform two-dimensional nanofilms [27]. Recently, we further
designed a tumor-targeting two-dimensional nanostructure, named MNP@GOMitP&HACD, based on MitP-modified and MNP-grafted graphene oxide (GO) and
HACD. Similarly, the magnetic assembling process could be induced under geomagnetic field (Fig. 3), forming nanofilms for coating the tumor cells.
20.4 Biomedical Application of Magnetic Supramolecular
Assemblies
20.4.1 Drug Delivery
Traditional chemotherapeutic drugs with small molecular weights are widely used in
clinic. However, their efficiency is frequently compromised by poor water solubility,
weak targeting specificity, and emergency of drug-resistant cancers. It is a feasible
20 Construction and Biomedical Application of Magnetic Supramolecular. . .
563
that possess mitochondrion-targeting ability. Owing to numerous cyclohexylalanine
pendants located around the core of MitP-MNPs, and abundant β-CD on the HACD
polymer, large-sized supramolecular assembly may be further achieved through the
hierarchically intermolecular organization. When HACD was added, a strong multivalent binding between the hydrophobic cyclohexyl group of MitP and β-CD’s
cavity induced the formation of the supramolecular nanofibers with 100–500 nm in
diameter and several micrometers in length.
Interestingly, the constructed one-dimensional supramolecular magnetic nanofibers could sensitively respond to various magnetic fields. This assembling process
has two critical properties: (1) the assembling direction of the nanofibers is strictly
along with the magnetic field. When the components were under the geomagnetic
field, the nanofibers could be gradually induced along with the direction of this field,
just like a campus; when treated by the artificial strong field, the nanofibers could be
formed along with the direction of this field. (2) The assembling rate of the
nanofibers is in proportion with the strength of magnetic field. Moreover, the
formation of nanofibers could also be regulated by light irradiation in the presence
of the photo-responsive molecule arylazopyrazoles carboxylate (AAP) as the competitive guest. Under the green light irradiation, AAP was transformed into transAAP, disrupting the assembling process of this nanofibers; under the UV irradiation,
trans-AAP is transformed into cis-AAP, and the nanofibers could be formed.
20.3.3 Two-Dimensional Magnetic Supramolecular Nanoassemblies
By using modified magnetic nanoparticles, two-dimensional magnetic supramolecular
nanostructures could be achieved on proper substrates or interfaces. In an early study,
Sun et al. realized polymer-mediated self-assembly of magnetic FePt nanoparticles to
form two-dimensional nanofilms. The magnetic FePt nanoparticles were firstly modified by the functional polymers poly(vinylpyrrolidone) (PVP) or poly(ethylenimine)
(PEI), followed by self-assembling on PEI-modified silicon oxide surface, generating
wide-range and uniform two-dimensional nanofilms [27]. Recently, we further
designed a tumor-targeting two-dimensional nanostructure, named MNP@GOMitP&HACD, based on MitP-modified and MNP-grafted graphene oxide (GO) and
HACD. Similarly, the magnetic assembling process could be induced under geomagnetic field (Fig. 3), forming nanofilms for coating the tumor cells.
20.4 Biomedical Application of Magnetic Supramolecular
Assemblies
20.4.1 Drug Delivery
Traditional chemotherapeutic drugs with small molecular weights are widely used in
clinic. However, their efficiency is frequently compromised by poor water solubility,
weak targeting specificity, and emergency of drug-resistant cancers. It is a feasible
20 Construction and Biomedical Application of Magnetic Supramolecular. . .
563