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Journal ArticleDOI

Polymeric worm micelles as nano-carriers for drug delivery.

01 Jul 2005-Nanotechnology (IOP Publishing)-Vol. 16, Iss: 7
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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Citations
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Journal ArticleDOI
TL;DR: In this article, the molecular interactions behind the structural change from spherical to elongated micelles, in both microscopic and macroscopic scale, triggered by hydroxy naphthalenes under salt free condition, were investigated under Newtonian and non-Newtonian flow regimes.

18 citations

Patent
15 Jun 2012
TL;DR: In this article, a method of making cytocompatible alginate gels and their use in the treatment of cardiomyopathy was described, which relates to the present invention.
Abstract: The present invention relates to a method of making cytocompatible alginate gels and their use in the treatment of cardiomyopathy.

18 citations

Journal ArticleDOI
TL;DR: The optimized size, charge, and shape suggest the solid lipid nanoparticles will migrate and accumulate in the colon tumor preventing its proliferation and subsequently leading to tumor shrinkage and cell death.
Abstract: Colorectal cancer is a global concern, and its treatment is fraught with non-selective effects including adverse side effects requiring hospital visits and palliative care. A relatively safe drug formulated in a bioavailability enhancing and targeting delivery platform will be of significance. Metformin-loaded solid lipid nanoparticles (SLN) were designed, optimized, and characterized for particle size, zeta potential, drug entrapment, structure, crystallinity, thermal behavior, morphology, and drug release. Optimized SLN were 195.01 ± 6.03 nm in size, −17.08 ± 0.95 mV with regard to surface charge, fibrous in shape, largely amorphous, and release of metformin was controlled. The optimized size, charge, and shape suggest the solid lipid nanoparticles will migrate and accumulate in the colon tumor preventing its proliferation and subsequently leading to tumor shrinkage and cell death.

17 citations

Journal ArticleDOI
TL;DR: It seems feasible that increases in both functionality and structural complexity could be achieved in block copolymer nanostructures by adopting non-equilibrium self-assembling systems, particular those exhibiting emergent behaviour.
Abstract: Functional materials based on the self-assembly of amphiphilic block copolymers have attracted considerable interest in areas such as pharmaceutics and separation systems, artificial vesicles, 6] templating of inorganic mesostructures, 8] and fabrication of linear or spatially separated arrays of metallic nanoparticles. 10] Amphiphilic block copolymers display diverse lyotropic phase behaviour such that a variety of supramolecular structures in the form of spherical or cylindrical micelles, hexagonal, cubic or bicontinuous liquid crystals, and unilamellar or multilamellar spherical vesicles can be assembled spontaneously depending on polymer molecular weight and concentration, block length and composition, solvent composition and temperature. Whilst such structures provide important functional platforms for the design of hybrid nanostructures incorporating drug sequestration, biomolecule encapsulation or inorganic templating, their shape and dynamical properties are generally restricted by equilibrium considerations. As a consequence, there are few reports for example on the spontaneous selfassembly of block copolymers into highly elongated tubular nanostructures; indeed, such architectures are generally produced by sequential processing involving for example the step-wise chemical degradation or hydrolysis of the core domains of cylindrical micelles rather than by de novo selforganization. It seems feasible that increases in both functionality and structural complexity could be achieved in block copolymer nanostructures by adopting non-equilibrium self-assembling systems, particular those exhibiting emergent behaviour. There are precedents for this approach in the use of conventional surfactants in reactive microemulsion systems that are subjected to temporally and spatially dependent mesoscale transformations involving metastable surfactant– inorganic hybrid nanostructures. Moreover, similar mechanisms may account for the unusual neuron-like calcium phosphate/polymer nanostructures produced in the presence of a poly(ethylene oxide)-b-polymethacrylic acid (E68MA6) block copolymer in which the MA domain was partially alkylated with dodecylamine. In general, however, there are few studies on the spontaneous assembly of amphiphilic block copolymers into kinetically trapped and dynamically active states because compared with conventional surfactants the increased molecular weight and hence decreased mobility of amphiphilic block copolymers restrict transformation of these systems into non-equilibrium metastable states. It is notable, therefore, that Ryan et al. have recently reported the formation of myelin-like multilamellar tubular structures when the diblock copolymer amphiphile, poly(ethylene oxide)-b-poly(1,2-butylene oxide) (E16B22), was placed in contact with water. [19]

17 citations

Journal ArticleDOI
27 Feb 2019-Langmuir
TL;DR: It is found that solubilization is regulated by a complex interplay between enthalpic and entropic contributions and that the spatial distribution can be controlled by the concentration and solubility of the guest compound in the dispersion medium.
Abstract: The solubilization of lyophobic compounds in block copolymer micelles has been extensively investigated but remains only partially understood. There is a need to understand the fundamental parameters that determine the spatial distribution of the solubilized compounds within the micelles. Controlling this feature is a key aspect in the design of drug delivery systems with tailored release properties. Using Scheutjens-Fleer self-consistent field (SF-SCF) computations, we found that solubilization is regulated by a complex interplay between enthalpic and entropic contributions and that the spatial distribution can be controlled by the concentration and solubility of the guest compound in the dispersion medium. Upon solubilization, a characteristic change in size and mass of the micelles is predicted. This can be used as a fingerprint to indirectly assess the spatial distribution. Based on these findings, we developed two experimental protocols to control and assess the spatial distribution of lyophobic compounds within block copolymer micelles.

17 citations

References
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Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
18 Apr 2003-Science
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

Journal ArticleDOI
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

Journal ArticleDOI
12 Feb 1999-Science
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