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In this paper, pod-like supramicelles with multicompartment hydrophobic cores kei prepared by self-assembly of amphiphilic N -phthaloylchitosan-g-poly N -vinylcaprolactam PHCS-g-PNVCL in aqueous medium. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Pei and pH presented significant influences on the size and size distribution of the supramicelles.
These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery. The online version of this article doi: In nature, compartmentalization is one of the essential requirements for life. For example, the cell membrane has the ability to keep intracellular components together and protect them from an outside environment. Multicompartment micelles, with a hydrophilic corona and a microphase-separated hydrophobic core, have received increasing attention over the last decade [ 2 — 5 ].
Due to their intrinsic properties, multicompartment micelles can selectively entrap and release different hydrophobic compounds simultaneously [ 3 ], thus are promising for a wide range of applications especially for drug delivery [ 26 ]. Currently, the main strategy to design and prepare multicompartment micelles is through self-assembling some block copolymers with a water-soluble segment and two or more mutually incompatible hydrophobic segments, such as hydrocarbon and fluorocarbon [ 7 — 11 ].
According to previous theoretical study, amphiphilic graft copolymers should also be 110865 to 18065 into multicompartment micelles as long as they have hydrophobic chains 108865 sufficient incompatibility [ 12 ]. However, to the best of our knowledge, few graft copolymer-based multicompartment micelles have been reported.
Because of its intrinsic properties, such leii non-toxic, biocompatible, and biodegradable [ 14 — 16 ], chitosan has been widely utilized in biological and pharmaceutical field, such as tissue engineering [ 1718 ], wound healing [ 1920 ], bioimaging [ 2122 ], and drug delivery [ 2324 ]. In this study, chitosan-based pod-like 1065 with multicompartment hydrophobic cores were formed by assembly of chitosan-based amphiphilic graft copolymers.
These novel biomaterial-based supramicelles combined the specifics of multicores and multicompartments simultaneously. At first, densely phthalic anhydride-grafted N -phthaloylchitosan PHCS was obtained by introducing phthalic anhydride into the backbone of chitosan.
The critical aggregation concentration CAC was determined by fluorescent spectroscopy using pyrene as fluorescent probe.
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The morphology of the prepared supramicelles was investigated oei transmission electron microscopy TEM and polarized light microscope PLM. The detailed procedure on the synthesis of the graft copolymer, preparation of supramicelles, and all characterization techniques are available in the supplementary information. With an amphiphilic graft copolymer PHCS-g-PNVCL of hydrophobic groups and hydrophilic polymer chains, a novel supramicelle with several multicompartment hydrophobic cores in pod-like shape was prepared by the typical precipitation method [ 25 ].
As shown by TEM in Fig. The PLM images Fig. Although the internal structure of the aggregates could not be visualized by PLM, the shape of the aggregates could be clearly identified as pod-like consistent with the TEM result.
TEM images of the supramicelles: PLM images of the 1086 under different magnifications. The scale bars are: It could be ,ei clearly that these mono hydrophobic cores are formed by light gray regions as well as darker domains. These light gray regions and darker domains are regarded as the formation of hydrophobic compartments [ 5 ]. The formation of these mini compartments could be attributed to the intramolecular self-assembly of the hydrophobic phthalic anhydride groups.
Under aqueous condition, these phthalic anhydride groups inclined to aggregate spontaneously into mini hydrophobic patches. These mini-domains distributed homogeneously in the hydrophobic cores which might be attributed to the regular arrangement of the phthalic anhydride-modified chitosan [ 26 pei. These continuous and homogeneous distributed domains provided a great deal of mini-hydrophobic compartments in the hydrophobic cores which oei promising applications in pharmaceutical field, such as drug delivery.
The self-assembly was driven by the hydrophobic interactions between the grafted phthalic anhydride groups and the hydrogen bonding between chitosan chains. Amphiphilic copolymers are able to self-assemble into aggregates with complex and lfi morphology under appropriate conditions.
For example, the amphiphilic copolymers with densely grafted hydrophobic groups could collapse and curl to form the micelles with multi-hydrophobic cores which are vividly called pearl necklace micelles in aqueous medium 110865 28 — 30 ]. In this work, the densely grafted hydrophobic leei anhydride groups of PHCS-g-PNVCL rendered the kei of the copolymer main chains, intermolecular and intramolecular aggregates formed subsequently. As the TEM image shown in Fig.
S4A, it could be seen clearly that a lot of cores black domains generated at the initial time. And then, the rest of these main chains after the intramolecular assembly changed their spatial configuration spontaneously to form apparent hydrophilic chains in water under the hydrophobic interactions and hydrogen bonding. These apparent hydrophilic chains and the grafted hydrophilic PNVCL chains stretched into aqueous medium to form a hydrophilic corona to stabilize the micelles as the amplified graph shown in Fig.
Because of the hydrogen bonding and the hydrophobic interactions between the main chains of the copolymers, several mono micelles would link together to generate the reported pod-like supramicelles with several hydrophobic cores and a supra hydrophilic corona, as shown in Fig.
It could also be observed from the TEM images in Fig. S4B-C that the polymers assembled into a micelle with a tail aggregates of the rest of the main chains which might be a transit state in the formation procedure of the supramicelles, and then these mono micelles were linked together by their tails to form the pod-like supramicelles, as shown in Fig. From this hypothesized schematic diagram, the PHCS chains curled together and the grafted hydrophobic phthalic anhydride groups assembled into hydrophobic mini-cores to reach a stable state in aqueous medium.
The CAC of the synthesized amphiphilic copolymer was determined by fluorescence spectroscopy using pyrene as fluorescent probe [ 31 ]. As shown in Fig. S3, a low CAC value of 0. To evaluate the stability of the supramicelles, the hydrodynamic properties of this colloidal system were monitored by DLS equipped with a Malvern Zetasizer Nano ZS instrument.
It is noted that hydrodynamic size given by DLS could be employed to characterize the stability of these supramicelles, although DLS gives a spherical-averaged size that is equal to neither the pod length nor the pod width [ 33 ]. This remarkable stability might be attributed to the stiff hydrophobic cores confined by hydrogen bonding, hydrophobic interactions, and the steric hindrance from the hydrophilic corona. The stability investigation indicated that this prepared supramicelles could be the promising candidates for drug delivery applications.
Furthermore, we found that pH and environmental temperature presented profound effects on the assembly of these supramicelles. TEM was carried out to observe the morphology of the supramicelles assembled at different pH Fig. Correspondingly, size and size distribution of these supramicelles were monitored by DLS Fig. The size of the supramicelle increased significantly as the pH stood at an acid level, and the lie distribution was lel broad which had been reached above 1.
An intuitional observation given by TEM showed that most of the supramicelles aggregated together with a disordered shape. However, the supramicelles became more uniform while the pH increased at a higher level above 7. Temperature was also an important factor which could influence the lwi and size distribution of the supramicelles.
These investigations indicated that pH and temperature are two important factors which could be employed to control the size and size distribution of the reported supramicelles.
An interesting pod-like supramicelle with several multicompartment hydrophobic cores and a supra corona was prepared in aqueous medium.
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The hydrogen bonding and hydrophobic interactions between the PHCS chains are supposed to be the main driving force of the self-assembly. The supramicelles had a pod-like shape with a lej of 2. The pH value and temperature are two factors to influence the size and size distribution of the supramicelles. These novel pod-like supramicelles with multicompartment hydrophobic cores provide a promising microscale structure for a wide range of applications such as templating materials, solubilization, and drug delivery.
Rapid Production of Mn3O4/rGO as an Efficient Electrode Material for Supercapacitor by Flame Plasma
Below is the link to the electronic supplementary material. National Center eli Biotechnology Information1865. Published online Oct Author information Article notes Copyright and License information Disclaimer.
Received Aug 10; Accepted Oct 7. Electronic supplementary material The online version of this 110865 doi: Chitosan, Graft copolymers, Amphiphiles, Self-assembly, Multicompartment supramicelles. Introduction In nature, compartmentalization is one of the essential requirements for life. Experimental Section The detailed procedure on the synthesis of the graft copolymer, preparation of supramicelles, and all characterization techniques are available in the supplementary information.
Results and Discussion With an amphiphilic graft copolymer PHCS-g-PNVCL of hydrophobic groups and hydrophilic polymer chains, a novel supramicelle with several multicompartment hydrophobic cores in pod-like shape was prepared by the typical precipitation method llei 25 ]. Open in a separate window.
Electronic supplementary material Below is the link to the electronic supplementary material. Contributor Information Jie Wang, Email: More than the sum of its parts. Simultaneous, segregated storage of two agents in a multicompartment micelle. Zhu J, Hayward RC. Wormlike micelles with microphase-separated cores from blends of amphiphilic AB and hydrophobic BC diblock copolymers.
Multicompartment block polymer micelles. Facile synthesis of multicompartment micelles based on biocompatible poly 3-hydroxyalkanoate Macromol. Self-assembly into multicompartment micelles and selective solubilization by hydrophilic-lipophilic-fluorophilic block copolymers. Design and synthesis of a two compartment micellar system based on the self-association behavior of poly N -acylethyleneimine end-capped with a fluorocarbon and a hydrocarbon chain.
Multicompartment micelles from Lek miktoarm stars in water. Morphologies of multicompartment micelles formed by ABC miktoarm star terpolymers. Laterally nanostructured vesicles, polygonal bilayer sheets, and segmented wormlike micelles. Complex domain architecture of multicompartment micelles from a linear ABC triblock copolymer revealed by cryogenic electron tomography. Polymerized micelles with compartments. Biocompatibility of injectable chitosan—phospholipid implant systems. Hejazi R, Amiji M.
Chitosan-based gastrointestinal delivery systems. Biological activity of chitosan: Strategies for effective oral insulin delivery with modified chitosan nanoparticles: Micropatterning of bioactive glass nanoparticles on chitosan membranes for spatial leii biomineralization. In situ forming and rutin-releasing chitosan hydrogels as injectable dressings for dermal wound healing. Biomedical applications of carboxymethyl chitosans. Chitosan chemistry and pharmaceutical perspectives.