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: The wormlike micelles could be employed as nanovectors for the intracellular delivery of hydrophobic drugs for cancer therapy and in the acidic microenvironment of endocytic vesicles.
52 citations
TL;DR: The prospective potential of polymer based analogs to serve as mucin mimic is suggested, apart from functioning as an artificial model, reducing the current dependency on animal models, can aid in furthering fundamental understanding of such complex structures.
Abstract: Mucin networks are viscoelastic fibrillar aggregates formed through the complex self-association of biopolymeric glycoprotein chains. The networks form a lubricious, hydrated protective shield along epithelial regions within the human body. The critical role played by mucin networks in impacting the transport properties of biofunctional molecules (e.g., biogenic molecules, probes, nanoparticles), and its effect on bioavailability are well described in the literature. An alternate perspective is provided in this paper, presenting mucin’s complex network structure, and its interdependent functional characteristics in human physiology. We highlight the recent advances that were achieved through the use of mucin in diverse areas of bioengineering applications (e.g., drug delivery, biomedical devices and tissue engineering). Mucin network formation is a highly complex process, driven by wide variety of molecular interactions, and the network possess structural and chemical variations, posing a great challenge to understand mucin’s bulk behavior. Through this review, the prospective potential of polymer based analogs to serve as mucin mimic is suggested. These analog systems, apart from functioning as an artificial model, reducing the current dependency on animal models, can aid in furthering our fundamental understanding of such complex structures.
51 citations
TL;DR: Interestingly, morphology transformation from spheres to a necklace and rod-like nanostructure was observed during the degradation procedure under basic condition and this shape reconstruction of PVP-PCL nanoparticles in the degradation process opens a new window to fabricate hierarchical supramolecular structures.
51 citations
TL;DR: It is reported that addition of the semicrystalline homopolymer PFDMS to monodisperse short (ca. 200 nm), cylindrical seed micelles of PFD MS results in the formation of aggregated structures by end-to-end coupling to form micelle networks.
Abstract: Cylindrical block copolymer micelles with a crystalline poly(ferrocenyldimethylsilane) (PFDMS) core and a long corona-forming block are known to elongate through an epitaxial growth mechanism on addition of further PFDMS block copolymer unimers. We now report that addition of the semicrystalline homopolymer PFDMS(28) to monodisperse short (ca. 200 nm), cylindrical seed micelles of PFDMS block copolymers results in the formation of aggregated structures by end-to-end coupling to form micelle networks. The resulting aggregates were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). In some cases, a core-thickening effect was also observed where the added homopolymer appeared to deposit and crystallize at the core-corona interface, which resulted in an increase of the width of the micelles within the networks. No evidence for aggregation was detected when the amorphous homopolymer poly(ferrocenylethylmethylsilane) (PFEMS(25)) was added to the cylindrical seed micelles whereas similar behavior to PFDMS(28) was noted for semicrystalline polyferrocenyldimethylgermane (PFDMG(30)). This suggested that the crystallinity of the added homopolymer is critical for subsequent end-to-end coupling and network formation to occur. We also explored the tendency of the cylindrical seed micelles to form aggregates by the addition of PI-b-PFDMS (PI = polyisoprene) block copolymers (block ratios 6:1, 3.8:1, 2:1, or 1:1), and striking differences were noted. The results ranged from typical micelle elongation, as reported in previous work, at high corona to core-forming block ratios (PI-b-PFDMS; 6:1) to predominantly end-to-end coupling at lower ratios (PI-b-PFDMS; 2:1, 1:1) to form long, essentially linear structures. The latter process, especially for the 2:1 block copolymer, led to much more controlled aggregate formation compared with that observed on addition of homopolymers.
50 citations
TL;DR: The spectroscopic studies highlight the role of changing core and corona solvation characteristics of the pluronic micelles in determining their rearrangement and the growth rate, which is first of its kind in the aqueous pluronic system.
Abstract: The salt induced sphere-to-rod growth in the micelles of the PEO−PPO triblock copolymers, Pluronic P123 (EO20PO70PEO20) and Pluronic P103 (EO16PO61PEO16), has been studied by dynamic light scattering (DLS), viscometry, and small angle neutron scattering (SANS) techniques. The observed micellar growths are found to be time dependent and have a strong variation in their growth rate with changing anion type and copolymer composition. The rate of growth increases rather significantly with an increase in the water structure making abilities of the anions along the Hofmeister series in the order Cl− < F−< (PO4)3−. This has been attributed to an increasing ability of these ions to dehydrate the micellar corona, a factor that plays an important role in inducing sphere-to-rod shape transition of the micelles. The copolymer composition also has a significant influence on the micellar growth rate, as the P103 with a smaller molecular weight than P123 shows a significantly faster growth of its micelles under similar ...
50 citations
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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