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Yoshio Okamoto - One of the best experts on this subject based on the ideXlab platform.
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Helix-Sense-Selective Radical Polymerization of N-(Triphenylmethyl)Methacrylamides and Properties of the Polymers
Polymer Journal, 2006Co-Authors: Naohiro Hoshikawa, Chiyo Yamamoto, Yuji Hotta, Yoshio OkamotoAbstract:N -(Triphenylmethyl)Methacrylamide (TrMAM) and N -[di(4-butylphenyl)-phenylmethyl]Methacrylamide (DBuTrMAM) were polymerized using a radical initiator. The obtained poly(TrMAM) was insoluble in common organic solvents, but poly(DBuTrMAM) was soluble in chloroform and THF. Both polymers were dissolved in conc. H_2SO_4 accompanied by cleavage of the side groups to give poly(Methacrylamide) (poly(MAM)). The ^1H NMR of the polymers in D_2SO_4 indicated that the polymers obtained at low temperature were nearly 100% isotactic. The poly(MAM) with almost 100% isotacticity showed a crystallinity. The poly(DBuTrMAM) formed a lyotropic crystalline phase in chloroform. The radical polymerization of the monomers in the presence of various chiral additives produced optically active polymers having a prevailing helicity. The optically active poly(TrMAM) exhibited a low chiral recognition.
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Helicity Induction in N-[(4-Butyl)triphenylmethyl]-Methacrylamide Sequence via Radical Copolymerization with Chiral Monomers
Polymer Journal, 2006Co-Authors: A K M Fakhrul Azam, Masami Kamigaito, Masashi Tsuji, Yoshio OkamotoAbstract:The radical copolymerization of N-[(4-butyl)triphenylmethyl]Methacrylamide (BuTrMAM) with optically active monomers, such as N-[(R)-(+)-1-(1-naphthyl)ethyl]Methacrylamide, N-[(S)-(−)-1-(1-naphthyl)ethyl]Methacrylamide, N-((S)-(+)-1-cyclohexylethyl)Methacrylamide, N-((R)-(−)-1-cyclohexylethyl)Methacrylamide, N-((S)-(−)-1-benzylpyrrolidin-3-yl)Methacrylamide, and N-((R)-(+)-1-benzylpyrrolidin-3-yl)Methacrylamide, was carried out. The optical activity of the obtained copolymers significantly depended on the monomer contents. When the chiral monomer content was low in the copolymers, the chiral monomeric units were effective in inducing an excess of the one-handed helix consisting of BuTrMAM monomeric sequences. The helicity induction was most effectively attained using N-[1-(1-naphthyl)ethyl]Methacrylamide at low temperature. The chiroptical properties and chiral recognition ability of the obtained copolymers were studied in detail.
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Helix-Sense-Selective Free Radical Polymerization of N-(Triphenylmethyl)Methacrylamide Derivatives
Polymer Journal, 2006Co-Authors: A K M Fakhrul Azam, Masami Kamigaito, Yoshio OkamotoAbstract:Two novel monomers, N -[(±)-(2-fluorophenyl)(4-fluorophenyl)(phenyl)methyl]Methacrylamide (2F4FPhMAM) and N -[(4-butyl)triphenylmethyl]Methacrylamide (BuTrMAM), were synthesized and polymerized in the presence of (+)- and (−)-menthol as the chiral additive at different temperatures. The obtained polymers, P2F4FPhMAM and PBuTrMAM, are optically active. P2F4FPhMAM is not soluble in common organic solvents and no enantiomer selection was observed in the polymerization of racemic 2F4FPhMAM in the presence of the optically active additive (+)- and (−)-menthols. PBuTrMAM is soluble in THF and chloroform. The circular dichroism spectra of the polymers is similar to that of optically active poly[(triphenylmethyl)Methacrylamide] with a prevailing one-handed helicity, suggesting that the present polymers also have a prevailing one-handed helicity. The tacticity of the polymers was estimated from the ^1H NMR spectrum of polyMethacrylamide derived in D_2SO_4. The polymers are almost 100% isotactic. The chiroptical properties of the obtained polymers were studied in detail.
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Synthesis, Chiroptical Properties, and Chiral Recognition Ability of Optically Active PolyMethacrylamides Having Various Tacticities
Polymer Journal, 2005Co-Authors: Kohei Morioka, Yutaka Isobe, Shigeki Habaue, Yoshio OkamotoAbstract:The radical polymerization of optically active Methacrylamides, such as N -[( R )-(+)-α-methylbenzyl]Methacrylamide, N -[( R )-(−)-1-cyclohexylethyl]Methacrylamide, N -[( R )-(+)-1-(1-naphthyl)ethyl]Methacrylamide, and N -[(1 R ,2 S )-(−)-1-(2-indanol)Methacrylamide, was carried out under various conditions. The polymerization in the presence of ytterbium trifluoromethanesulfonate [Yb(OTf)_3] produced isotactic-rich polymers compared with those obtained without the Lewis acid. The specific rotations and the circular dichroism spectral patterns of the obtained polymers varied with the tacticities, suggesting that the tacticities influence the secondary structures of the polymers. The IR spectra of the polymers indicated that the isotactic polymers favorably formed intramolecular hydrogen bonds. The chiral recognition ability of the optically active polymers immobilized on silica gel was evaluated as the chiral stationary phases for high-performance liquid chromatography (HPLC).
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Synthesis and chiral recognition ability of optically active poly{N-[(R)-α-methoxycarbonylbenzyl]Methacrylamide} with various tacticities by radical polymerization using Lewis acids
Journal of Polymer Science Part A: Polymer Chemistry, 2003Co-Authors: Kohei Morioka, Yutaka Isobe, Shigeki Habaue, Yoshikatsu Suito, Yoshio OkamotoAbstract:The radical polymerization of an optically active Methacrylamide, N-[(R)-a-methoxycarbonylbenzyl]Methacrylamide, was carried out in the absence and presence of Lewis acids such as yittribium trifluoromethanesulfonate [Yb(OTf) 3 ] and scandium trifluoromethanesulfonate [Sc(OTf) 3 ]. Catalytic amounts of the Lewis acids significantly affected the stereoregularity of the obtained polymers. The polymerization with Yb(OTf) 3 in tetrahydrofuran afforded isotactic polymers (up to mm = 87%), whereas the conventional radical method without the Lewis acid produced polymers rich in syndiotacticity (up to rr = 88%). The radical polymerization in the presence of MgBr 2 proceeded in a heterotactic-selective manner (mr = 63%). Thus, the isotactic, syndiotactic, and heterotactic poly(Methacrylamide)s were synthesized by the radical processes. The chiral recognition abilities of the obtained optically active poly(Methacrylamide) were affected by the stereoregularity.
Kalina Peneva - One of the best experts on this subject based on the ideXlab platform.
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Indole, Phenyl, and Phenol Groups: The Role of the Comonomer on Gene Delivery in Guanidinium Containing Methacrylamide Terpolymers.
Macromolecular rapid communications, 2020Co-Authors: Franz J. Hack, Kalina Peneva, Ceren Cokca, Sebastian Städter, Juliana Hülsmann, Dagmar FischerAbstract:This report highlights the importance of hydrophobic groups mimicking the side chains of aromatic amino acids, which are tryptophan, phenylalanine, and tyrosine, in guanidinium bearing poly(Methacrylamide)s for the design of non-viral gene delivery agents. Guanidinium containing Methacrylamide terpolymers are prepared by aqueous reversible addition-fragmentation chain transfer (aRAFT) polymerization with different hydrophobic monomers, N-(2-indolethyl)Methacrylamide (IEMA), N-phenethylMethacrylamide (PhEMA), or N-(4-hydroxyphenethyl)Methacrylamide (PhOHEMA) by aiming similar contents. The well-defined polymers are obtained with a molar mass of ≈15 000 g mol-1 and ≈1.1 dispersity. All terpolymers demonstrate almost comparable in vitro cell viability and hemocompatibility profiles independent of the type of side chain. Although they all form positively charged, enzymatically stable polyplexes with plasmid DNA smaller than 200 nm, the incorporation of the IEMA monomer improve these parameters by demonstrating a higher DNA binding affinity and forming nanoassemblies of about 100 nm. These physicochemical characteristics are correlated with increased transfection rates in CHO-K1 cells dependent on the type of the monomer and the nitrogen to phosphate (N/P) ratio of the polyplexes, as determined by luciferase reporter gene assays.
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Incorporation of Indole Significantly Improves the Transfection Efficiency of Guanidinium-Containing Poly(Methacrylamide)s
Macromolecular rapid communications, 2020Co-Authors: Ceren Cokca, Ilja Tabujew, Dagmar Fischer, Leon Zartner, Kalina PenevaAbstract:A highly efficient transfection agent is reported that is based on terpolymer consisting of N-(2-hydroxypropyl)Methacrylamide (HPMA), N-(3-guanidinopropyl) Methacrylamide (GPMA), and N-(2-indolethyl)Methacrylamide monomers (IEMA) by analogy to the amphipathic cell-penetrating peptides containing tryptophan and arginine residues. The incorporation of the indole-bearing monomer leads to successful plasmid DNA condensation even at a nitrogen-to-phosphate (N/P) ratio of 1. The hydrodynamic diameter of polyplexes is determined to be below 200 nm for all N/P ratios. The transfection studies demonstrate a 200-fold increase of the transgene expression in comparison to P(HPMA-co-GPMA) with the same guanidinium content. This study reveals the strong potential of the indole group as a side-chain pendant group that can increase the cellular uptake of polymers and the transfection efficiency of the respective polyplexes.
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the guanidinium group as a key part of water soluble polymer carriers for sirna complexation and protection against degradation
Macromolecular Rapid Communications, 2014Co-Authors: Ilja Tabujew, Christoph Freidel, Bettina Krieg, Mark Helm, Kaloian Koynov, Klaus Mullen, Kalina PenevaAbstract:: Here, the preparation of a novel block copolymer consisting of a statistical copolymer N-(2-hydroxypropyl) Methacrylamide-s-N-(3-aminopropyl) Methacrylamide and a short terminal 3-guanidinopropyl Methacrylamide block is reported. This polymer structure forms neutral but water-soluble nanosized complexes with siRNA. The siRNA block copolymer complexes are first analyzed using agarose gel electrophoresis and their size is determined with fluorescence correlation spectroscopy. The protective properties of the polymer against RNA degradation are investigated by treating the siRNA block copolymer complexes with RNase V1. Heparin competition assays confirm the efficient release of the cargo in vitro. In addition, the utilization of microscale thermophoresis is demonstrated for the determination of the binding strength between a fluorescently labeled polyanion and a polymer molecule.
J C Leroux - One of the best experts on this subject based on the ideXlab platform.
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synthesis and micellar characterization of novel amphiphilic a b a triblock copolymers of n 2 hydroxypropyl Methacrylamide or n vinyl 2 pyrrolidone with poly e caprolactone
Macromolecules, 2002Co-Authors: B S Lele, J C LerouxAbstract:Two novel A−B−A type amphiphilic triblock copolymers, namely poly(N-(2-hydroxypropyl)Methacrylamide)-block-poly(e-caprolactone)-block-poly(N-(2-hydroxypropyl)Methacrylamide) (PHPMA-b-PCL-b-PHPMA) and poly(N-vinyl-2-pyrrolidone)-block-poly(e-caprolactone)-block-poly(N-vinyl-2-pyrrolidone) (PVP-b-PCL-b-PVP), were synthesized and characterized. These polymers were prepared by free radical polymerization of N-(2-hydroxypropyl)Methacrylamide and N-vinyl-2-pyrrolidone in the presence of a novel biodegradable, macromolecular chain-transferring agent, α,ω-poly(e-caprolactone) dithiol (HS-PCL-SH). All triblock copolymers self-assembled in aqueous solutions to form supramolecular aggregates of 30−200 nm size. The critical aggregation concentration of the polymers ranged from 1 to 4 mg/L. The partition equilibrium constant (Kv) of pyrene in the hydrophobic core of micelles was comprised between 2.5 × 105 and 4.2 × 105. The triblock copolymer micelles were loaded by a dialysis procedure with 1−4% (w/w) of two model p...
Jeanchristophe Leroux - One of the best experts on this subject based on the ideXlab platform.
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triblock and star block copolymers of n 2 hydroxypropyl Methacrylamide or n vinyl 2 pyrrolidone and d l lactide synthesis and self assembling properties in water
Polymer, 2004Co-Authors: Ning Kang, Jeanchristophe LerouxAbstract:Abstract Novel A-B-A triblock and star-block amphiphilic copolymers, i.e. poly(N-(2-hydroxypropyl)Methacrylamide)-block-poly( d , l -lactide)-block-poly(N-(2-hydroxypropyl)metha-crylamide), poly(N-vinyl-2-pyrrolidone)-block-poly( d , l -lactide)-block-poly(N-vinyl-2-pyrrolidone), star-poly( d , l -lactide)-block-poly(N-(2-hydroxypropyl)Methacrylamide) and star-poly( d , l -lactide)-block-poly(N-vinylpyrrolidone), were synthesized and characterized. These polymers were prepared by free radical polymerization of N-(2-hydroxypropyl)Methacrylamide and N-vinyl-2-pyrrolidone in the presence of either poly( d , l -lactide) dithiol or star-poly( d , l -lactide) tetrakis-thiol, both biodegradable macromolecular chain-transferring agents. All copolymers self-assembled in aqueous solution to form supramolecular aggregates of 20–180 nm in size. The critical aggregation concentration of the copolymers ranged from 5 to 24 mg/L, depending on their hydrophobicity. The partition equilibrium constant of pyrene in the hydrophobic core of micelles was between 0.71×105 and 1.63×105. The triblock copolymer micelles were loaded with two model poorly water-soluble drugs, namely, indomethacin (1.5–16.4% w/w) and paclitaxel (0.4–1.5% w/w), by a dialysis procedure. These triblock and star-block copolymers could prove useful as nanocarriers for the solubilization and delivery of hydrophobic drugs.
Brian C. Benicewicz - One of the best experts on this subject based on the ideXlab platform.
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Preparation and Properties of Poly(Methacrylamide)s Containing Oligoaniline Side Chains
Macromolecules, 2003Co-Authors: Ru Chen, Brian C. BenicewiczAbstract:New poly(Methacrylamide)s containing oligoaniline side chains were synthesized and characterized. Oligoanilines were prepared by palladium-catalyzed amination, followed by reaction with methacryloyl chloride to give Methacrylamide monomers. Polymers were prepared by free radical polymerization. The polymers were prepared in the leucoemeraldine state and were oxidized to the emeraldine state by exposure to oxygen gas. The electrochemical characterization of these polymers by cyclic voltammetry indicated that the redox behaviors were similar to the corresponding oligoanilines.