Polymeric worm micelles as nano-carriers for drug delivery.
TL;DR: W worm micelles as blends of degradable polylactic acid and inert block copolymer amphiphiles were prepared for controlled release and initial study of carrier transport through nano-porous media, suggesting a new class of hydrophobic drug nano-carriers that are capable of tissue permeation as well as controlled release.
Abstract: Nanoscale carriers of active compounds, especially drugs, need not be spherical in shape. Worm micelles as blends of degradable polylactic acid (PLA) and inert block copolymer amphiphiles were prepared for controlled release and initial study of carrier transport through nano-porous media. The loading capacity of a typical hydrophobic drug, Triamterene, and the release of hydrophobic dyes were evaluated together with morphological changes of the micelles. Degradation of PLA by hydrolysis led to the self-shortening of worms and a clear transition towards spherical micelles, correlating with the release of hydrophobic dyes. Perhaps equally important for application is the flexibility of worm micelles, which we show allows them to penetrate nanoporous gels where 100 nm sized vesicles cannot enter. Such gels have served as tissue models, and so the results here collectively suggest a new class of hydrophobic drug nano-carriers that are capable of tissue permeation as well as controlled release.
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TL;DR: In this paper , the formation of fiber-like micelles from the perspectives of fundamental driving forces and molecular interactions involved in the solution self-assembly process is summarized and discussed.
Abstract: One-dimensional (1D) nanoscale objects abundant in nature commonly possess hierarchical structures and are generally constructed via bottom-up self-assembly strategies. The unique high aspect ratio morphology of the assembled nanofibrillar materials, such as collagen, cellulose, and silk, together with highly ordered architectures, endows a range of remarkable functionalities in nature. Inspired by this hierarchical building principle, block copolymers (BCPs) have been developed and employed to engineer man-made functional 1D nanostructures and as models to study the self-assembly process. The rapid development of advanced polymerization techniques allows for the precise design of BCPs and the resulting assemblies with intensive studies on distinct structure–property–function relationships. In this Review, we summarize and discuss the formation of fiber-like micelles from the perspectives of fundamental driving forces and molecular interactions involved in the solution self-assembly process. Three main formation mechanisms are highlighted, including covalent bonding, volume exclusion, and crystallization, which are involved in the corresponding domains of coronal, interfacial, and core segments of BCPs. Two spatiotemporal levels of fiber-like assemblies are discussed. In addition, the emerging applications and a general guidance for the rational design of advanced BCPs are proposed in light of the unique traits of fiber-like micelles.
6 citations
TL;DR: It is demonstrated that slugs that form in a microchamber can be driven to migrate through the microchannels, as well as steered to a particular direction at microchannel intersections, indicating that slug movements can be more effectively controlled in microch channels, and potentially useful for bio-actuation applications.
Abstract: This paper investigates the light-driven migration of the multi-cellular microorganism Dictyostelium discoideum as a potential bio-actuation mechanism in microsystems. As a platform for slug migration we use microscale confinements, which consist of intersecting microchannels fabricated from solidified agar-water solution. The agar surface provides necessary moisture to the slugs during the experiment while remaining sufficiently stiff to allow effective slug migration. The movements of the slugs in the microchannels are driven and guided by phototaxis via controlling light transmitted through optical fibers. The microchannels impose geometrical confinements on the migrating slugs, improving the spatial precision of the migration. We demonstrate that slugs that form in a microchamber can be driven to migrate through the microchannels, as well as steered to a particular direction at microchannel intersections. Our experimental results indicate that slug movements can be more effectively controlled in microchannels, and potentially useful for bio-actuation applications. (C) 2012 Elsevier B.V. All rights reserved.
6 citations
Cites methods from "Polymeric worm micelles as nano-car..."
...Microorganisms have been used as bio-microactuators to move fluids [6], transport microscale objects [7,8], drive microrotors [4], and...
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TL;DR: In this article, the solution self-assembly pathways of polypeptoid block copolymers are investigated and molecular packing and crystallization of these building blocks are shown to affect the selfassembly behavior, resulting in one-dimensional, two-dimensional and multidimensional hierarchical polymeric nanostructures in solution.
Abstract: Polypeptoids, a class of synthetic peptidomimetic polymers, have attracted increasing attention due to their potential for biotechnological applications, such as drug/gene delivery, sensing and molecular recognition. Recent investigations on the solution self-assembly of amphiphilic block copolypeptoids highlighted their capability to form a variety of nanostructures with tailorable morphologies and functionalities. Here, we review our recent findings on the solutions self-assembly of coil-crystalline diblock copolypeptoids bearing alkyl side chains. We highlight the solution self-assembly pathways of these polypeptoid block copolymers and show how molecular packing and crystallization of these building blocks affect the self-assembly behavior, resulting in one-dimensional (1D), two-dimensional (2D) and multidimensional hierarchical polymeric nanostructures in solution.
6 citations
TL;DR: In this article, the authors focus on small, spherically symmetric aggregates in a solution of sphere-forming amphiphile mixed with a smaller amount of lamella-forming amphibian.
Abstract: Binary mixtures of amphiphiles in solution can self-assemble into a wide range of structures when the two species individually form aggregates of different curvatures. In this paper, we focus on small, spherically symmetric aggregates in a solution of sphere-forming amphiphile mixed with a smaller amount of lamella-forming amphiphile. Using a coarse-grained mean-field model (self-consistent field theory, or SCFT), we scan the parameter space of this system and find a range of morphologies as the interaction strength, architecture, and mixing ratio of the amphiphiles are varied. When the two species are quite similar in architecture, or when only a small amount of lamella-former is added, we find simple spherical micelles with cores formed from a mixture of the hydrophobic blocks of the two amphiphiles. For more strongly mismatched amphiphiles and higher lamella-former concentrations, we instead find small vesicles and more complex micelles. In these latter structures, the lamella-forming species is encaps...
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References
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TL;DR: The utility of polymeric micelles formed through the multimolecular assembly of block copolymers as novel core-shell typed colloidal carriers for drug and gene targeting and their feasibility as non-viral gene vectors is highlighted.
3,457 citations
TL;DR: This review examines the chemical nature of polymeric micelles as well as the methods used to characterize them with regard to drug delivery and potential medical applications, especially in cancer chemotherapy, are described and discussed.
1,200 citations
TL;DR: Experiments with poly(1,2-butadiene-b-ethylene oxide) diblock copolymers are described, which form Y-junctions and three-dimensional networks in water at weight fractions of PEO intermediate to those associated with vesicle and wormlike micelle morphologies.
Abstract: Amphiphilic compounds such as lipids and surfactants are fundamental building blocks of soft matter. We describe experiments with poly(1,2-butadiene-b-ethylene oxide) (PB-PEO) diblock copolymers, which form Y-junctions and three-dimensional networks in water at weight fractions of PEOintermediate to those associated with vesicle and wormlike micelle morphologies. Fragmentation of the network produces a nonergodic array of complex reticulated particles that have been imaged by cryogenic transmission electron microscopy. Data obtained with two sets of PB-PEOcompounds indicate that this type of self-assembly appears above a critical molecular weight. These block copolymers represent versatile amphiphiles, mimicking certain low molecular weight three-component (surfactant/water/oil) microemulsions, without addition of a separate hydrophobe.
1,126 citations
TL;DR: With all compositions, in both 100 nm and giant vesicles, the average release time reflects a highly quantized process in which any given vesicle is either intact and retains its encapsulant, or is porated and slowly disintegrates.
638 citations
TL;DR: A low molecular weight poly(ethyleneoxide)-poly(butadiene) (PEO-PB) diblock copolymer containing 50 weight percent PEO forms gigantic wormlike micelles at low concentrations (<5 percent by weight) in water.
Abstract: A low molecular weight poly(ethyleneoxide)-poly(butadiene) (PEO-PB) diblock copolymer containing 50 weight percent PEO forms gigantic wormlike micelles at low concentrations (<5 percent by weight) in water. Subsequent generation of free radicals with a conventional water-based redox reaction leads to chemical cross-linking of the PB cores without disruption of the cylindrical morphology, as evidenced by cryotransmission electron microscopy and small-angle neutron scattering experiments. These wormlike rubber micelles exhibit unusual viscoelastic properties in water.
626 citations