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 article, the fabrication of core-crosslinked, fluorescent, and surface functionalized worm-like block copolymer micelles as drug delivery vehicles was reported using anionic ring opening polymerization and self-assembly in water as a selective solvent led to the formation of long filomicelles.
8 citations
01 Jul 2013
TL;DR: This chapter presents the nature and impact of nanoparticle design on tumor accumulation, particularly in the context of the tumor microenvironment, and strategies to overcome them and enhance the effective delivery of nanoparticles are presented.
Abstract: Nanoparticles have been employed in cancer management as vectors to deliver chemotherapeutic and/or imaging agents to tumors. Enhanced tumor accumulation occurs by virtue of the long circulation properties of the nanocarrier and the enhanced permeability and retention effect that is characteristic of solid tumors. The versatility of the nanoparticle platform has enabled the design and development of various nanocarriers differing in physicochemical properties such as surface composition, size, charge, and shape. While such properties can influence the pharmacokinetics and biodistribution of a formulation, total tumor deposition can be further impacted by inherent pathophysiology of the tissue. This chapter presents the nature and impact of nanoparticle design on tumor accumulation, particularly in the context of the tumor microenvironment. In vivo barriers, such as opsonization, impaired tumor blood flow, heterogeneous vascular and interstitial permeability impede the effective delivery of nanocarriers and their cargo and are discussed herein, while strategies to overcome them and enhance the effective delivery of nanoparticles are presented.
7 citations
TL;DR: In this paper, a combination of rheology and magnetic resonance known as "rheo-NMR" was used to observe the shear and field-dependent dynamics of orientational order in a wormlike micelle (WLM).
Abstract: Using a combination of rheology and magnetic resonance known as “rheo-NMR” we observe, in real time, the shear- and field-dependent dynamics of orientational order in a wormlike micelle (WLM). We construct a dynamical phase diagram, yielding a range where bistable shear-activated phase switching occurs in which WLMs are stably isotropic (> 12 h) before shearing, and yet realign with B0 after shearing. Furthermore, we extract anisotropic viscoelastic coefficients for the first time in a WLM by precisely fitting nonlinear realignment data. This deepened understanding of complex surfactant fluid dynamics lights a path toward increased materials control in advanced lubricants and coatings, drug delivery, and tissue engineering.
7 citations
TL;DR: In this article, the microphase separation of symmetric diblock copolymers with variable block stiffness and different block chain length was studied using coarse-grained molecular dynamics simulations, and it was shown that a combination of chain length and relative stiffness between the blocks may play the major role in determining the equilibrium morphology of the system.
Abstract: The authors have studied the microphase separation of symmetric diblock copolymers with variable block stiffness and different block chain lengths using coarse-grained molecular dynamics simulations. The simulation results show that for symmetric diblock copolymers, a combination of chain length and relative stiffness between the blocks may play the major role in determining the equilibrium morphology of the system. When the variation in stiffness between blocks is small, the equilibrium morphology of the diblock system is found to be lamellar; this is also the case for systems with small chain lengths, regardless of the difference in block stiffness. However, in systems with longer chains with modest variation in stiffness between the blocks, an ordered cylindrical phase is formed in which the stiffer blocks form cylinders completely surrounded by the flexible components. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2556–2565, 2009
7 citations
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