The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform
Ijeoma F. Uchegbu - One of the best experts on this subject based on the ideXlab platform.
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Controls on Polymer Molecular Weight May Be Used To Control the Size of Palmitoyl Glycol Chitosan Polymeric Vesicles
Langmuir, 2001Co-Authors: Wei Wang, Anne Marie Mcconaghy, Laurence Tetley, Ijeoma F. UchegbuAbstract:For the first time, to our knowledge, it has been demonstrated that Polymeric Vesicle size may be controlled by controls on polymer molecular weight. A direct relationship exists between the square root of the palmitoyl glycol chitosan molecular weight and sonicated Polymeric Vesicle z-average mean diameter (r = 0.95). Glycol chitosan samples of varying molecular weight were prepared by hydrolysis with 4 M hydrochloric acid and palmitoyl glycol chitosan samples of varying molecular weight synthesized by reacting glycol chitosan with palmitic acid N-hydroxysuccinimide ester. Polymer characterization was carried out by gel permeation chromatography/laser light scattering and 1H NMR. Vesicles produced from the various palmitoyl glycol chitosan samples by probe sonication in the presence of cholesterol were sized and imaged by transmission electron microscopy. Palmitoyl glycol chitosan samples of MW 276 000, 134 000, 89 000, 28 000, and 31 000 produced unilamellar Polymeric Vesicles with a z-average mean diam...
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liposomes encapsulating Polymeric chitosan based Vesicles a Vesicle in Vesicle system for drug delivery
International Journal of Pharmaceutics, 2000Co-Authors: Deborah Mcphail, Laurence Tetley, Christine Dufes, Ijeoma F. UchegbuAbstract:Drug delivery systems comprising Vesicles prepared from one amphiphile encapsulating Vesicles prepared from a second amphiphile have not been prepared previously due to a tendency of the bilayer components of the different Vesicles to mix during preparation. Recently we have developed Polymeric Vesicles using the new polymer-palmitoyl glycol chitosan and cholesterol in a 2:1 weight ratio. These Polymeric Vesicles have now been encapsulated within egg phosphatidylcholine (egg PC), cholesterol (2:1 weight ratio) liposomes yielding a Vesicle in Vesicle system. The Vesicle in Vesicle system was visualised by freeze fracture electron microscopy. The mixing of the different bilayer components was studied by monitoring the excimer fluorescence of pyrene-labelled Polymeric Vesicles after their encapsulation within egg PC liposomes or hexadecyl diglycerol ether niosomes. A minimum degree of lipid mixing was observed with the Polymeric Vesicle-egg PC liposome system when compared to the Polymeric Vesicle-hexadecyl diglycerol ether niosome system. The Polymeric Vesicle-egg PC Vesicle in Vesicle system was shown to retard the release of encapsulated solutes. 28% of 5(6)-carboxyfluorescein (CF) encapsulated in the Polymeric Vesicle compartment of the Vesicle in Vesicle system was released after 4 h compared to the release of 62% of encapsulated CF from plain Polymeric Vesicles within the same time period.
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Preliminary characterization of novel amino acid based Polymeric Vesicles as gene and drug delivery agents.
Bioconjugate chemistry, 2000Co-Authors: Maureen D. Brown, Laurence Tetley, Andreas G. Schätzlein, A Brownlie, V. Jack, W. Wang, And A. I. Gray, Ijeoma F. UchegbuAbstract:The amino acid homopolymers, poly-L-lysine and poly-L-ornithine, have been modified by the covalent attachment of palmitoyl and methoxypoly(ethylene glycol) (mPEG) residues to produce a new class of amphiphilic polymers-PLP and POP, respectively. These amphiphilic amino acid based polymers have been found to assemble into Polymeric Vesicles in the presence of cholesterol. Representatives of this new class of Polymeric Vesicles have been evaluated in vitro as nonviral gene delivery systems with a view to finding delivery systems that combine effective gene expression with low toxicity in vivo. In addition, the drug-carrying capacity of these Polymeric Vesicles was evaluated with the model drug doxorubicin. Chemical characterization of the modified polymers was carried out using (1)H NMR spectroscopy and the trinitrobenzene sulfonic acid (TNBS) assay for amino groups. The amphiphilic polymers were found to have an unreacted amino acid, palmitoyl, mPEG ratio of 11:5:1, and Polymeric Vesicle formation was confirmed by freeze-fracture electron microscopy and drug encapsulation studies. The resulting Polymeric Vesicles, by virtue of the mPEG groups, bear a near neutral zeta-potential. In vitro biological testing revealed that POP and PLP Vesicle-DNA complexes are about one to 2 orders of magnitude less cytotoxic than the parent polymer-DNA complexes although more haemolytic than the parent polymer-DNA complexes. The Polymeric Vesicles condense DNA at a polymer:DNA weight ratio of 5:1 or greater and the Polymeric Vesicle-DNA complexes improved gene transfer to human tumor cell lines in comparison to the parent homopolymers despite the absence of receptor specific ligands and lysosomotropic agents such as chloroquine.
Laurence Tetley - One of the best experts on this subject based on the ideXlab platform.
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Controls on Polymer Molecular Weight May Be Used To Control the Size of Palmitoyl Glycol Chitosan Polymeric Vesicles
Langmuir, 2001Co-Authors: Wei Wang, Anne Marie Mcconaghy, Laurence Tetley, Ijeoma F. UchegbuAbstract:For the first time, to our knowledge, it has been demonstrated that Polymeric Vesicle size may be controlled by controls on polymer molecular weight. A direct relationship exists between the square root of the palmitoyl glycol chitosan molecular weight and sonicated Polymeric Vesicle z-average mean diameter (r = 0.95). Glycol chitosan samples of varying molecular weight were prepared by hydrolysis with 4 M hydrochloric acid and palmitoyl glycol chitosan samples of varying molecular weight synthesized by reacting glycol chitosan with palmitic acid N-hydroxysuccinimide ester. Polymer characterization was carried out by gel permeation chromatography/laser light scattering and 1H NMR. Vesicles produced from the various palmitoyl glycol chitosan samples by probe sonication in the presence of cholesterol were sized and imaged by transmission electron microscopy. Palmitoyl glycol chitosan samples of MW 276 000, 134 000, 89 000, 28 000, and 31 000 produced unilamellar Polymeric Vesicles with a z-average mean diam...
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liposomes encapsulating Polymeric chitosan based Vesicles a Vesicle in Vesicle system for drug delivery
International Journal of Pharmaceutics, 2000Co-Authors: Deborah Mcphail, Laurence Tetley, Christine Dufes, Ijeoma F. UchegbuAbstract:Drug delivery systems comprising Vesicles prepared from one amphiphile encapsulating Vesicles prepared from a second amphiphile have not been prepared previously due to a tendency of the bilayer components of the different Vesicles to mix during preparation. Recently we have developed Polymeric Vesicles using the new polymer-palmitoyl glycol chitosan and cholesterol in a 2:1 weight ratio. These Polymeric Vesicles have now been encapsulated within egg phosphatidylcholine (egg PC), cholesterol (2:1 weight ratio) liposomes yielding a Vesicle in Vesicle system. The Vesicle in Vesicle system was visualised by freeze fracture electron microscopy. The mixing of the different bilayer components was studied by monitoring the excimer fluorescence of pyrene-labelled Polymeric Vesicles after their encapsulation within egg PC liposomes or hexadecyl diglycerol ether niosomes. A minimum degree of lipid mixing was observed with the Polymeric Vesicle-egg PC liposome system when compared to the Polymeric Vesicle-hexadecyl diglycerol ether niosome system. The Polymeric Vesicle-egg PC Vesicle in Vesicle system was shown to retard the release of encapsulated solutes. 28% of 5(6)-carboxyfluorescein (CF) encapsulated in the Polymeric Vesicle compartment of the Vesicle in Vesicle system was released after 4 h compared to the release of 62% of encapsulated CF from plain Polymeric Vesicles within the same time period.
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Preliminary characterization of novel amino acid based Polymeric Vesicles as gene and drug delivery agents.
Bioconjugate chemistry, 2000Co-Authors: Maureen D. Brown, Laurence Tetley, Andreas G. Schätzlein, A Brownlie, V. Jack, W. Wang, And A. I. Gray, Ijeoma F. UchegbuAbstract:The amino acid homopolymers, poly-L-lysine and poly-L-ornithine, have been modified by the covalent attachment of palmitoyl and methoxypoly(ethylene glycol) (mPEG) residues to produce a new class of amphiphilic polymers-PLP and POP, respectively. These amphiphilic amino acid based polymers have been found to assemble into Polymeric Vesicles in the presence of cholesterol. Representatives of this new class of Polymeric Vesicles have been evaluated in vitro as nonviral gene delivery systems with a view to finding delivery systems that combine effective gene expression with low toxicity in vivo. In addition, the drug-carrying capacity of these Polymeric Vesicles was evaluated with the model drug doxorubicin. Chemical characterization of the modified polymers was carried out using (1)H NMR spectroscopy and the trinitrobenzene sulfonic acid (TNBS) assay for amino groups. The amphiphilic polymers were found to have an unreacted amino acid, palmitoyl, mPEG ratio of 11:5:1, and Polymeric Vesicle formation was confirmed by freeze-fracture electron microscopy and drug encapsulation studies. The resulting Polymeric Vesicles, by virtue of the mPEG groups, bear a near neutral zeta-potential. In vitro biological testing revealed that POP and PLP Vesicle-DNA complexes are about one to 2 orders of magnitude less cytotoxic than the parent polymer-DNA complexes although more haemolytic than the parent polymer-DNA complexes. The Polymeric Vesicles condense DNA at a polymer:DNA weight ratio of 5:1 or greater and the Polymeric Vesicle-DNA complexes improved gene transfer to human tumor cell lines in comparison to the parent homopolymers despite the absence of receptor specific ligands and lysosomotropic agents such as chloroquine.
Xianwu Jing - One of the best experts on this subject based on the ideXlab platform.
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co 2 sensitive amphiphilic triblock copolymer self assembly morphology transition and accelerating drug release from Polymeric Vesicle
Chinese Journal of Polymer Science, 2018Co-Authors: Xianwu Jing, Zhiyu Huang, Baogang WangAbstract:A series of triblock copolymers, containing a CO2-switchable block poly(2-(dimethylamino)ethyl methacrylate) (PDM) block and two symmetrical hydrophilic blocks polyacrylamide (PAM), were synthesized using atom transfer radical polymerization (ATRP) method. The pH and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO2, and the triblock copolymer aqueous solution displayed a CO2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the viscosity variation was the result of a unilamellar Vesicle-network aggregate structure transition. The release of rhodamine B from the Vesicles with and without CO2 stimuli showed the potential application in drug delivery domains; after CO2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO2-switchable morphology changes and CO2-induced drug release was proposed.
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CO2-switchable Vesicles-network structure transition and drug release property
Journal of Dispersion Science and Technology, 2017Co-Authors: Wenmeng Duan, Xianwu Jing, Lu Wang, Hongsheng LuAbstract:ABSTRACTA series of amphiphilic triblock polymers based on poly(ethylene glycol) (PEG) and two symmetrical poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) blocks was synthesized via the Atom Transfer Radical Polymerization (ATRP) method. Conductivity, pH, and viscosity tests demonstrated the CO2-switchability jointly; Cryogenic transmission electron microscopy (Cryo-TEM), Dynamic light scattering (DLS) revealed the self-assembly morphology transformation from unilamellar Vesicle to network structure when bubbling CO2. These changes were all attributed to the protonation of tertiary amine groups in PDMAEMA blocks and the mechanism was proved by −H NMR. The Vesicles have a relatively low release rate of drug; once stimulated by CO2, the release rate will be accelerated. The Polymeric Vesicle has the possibility to find potential applications in drug delivery and release domains.
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co2 switchable Polymeric Vesicle network structure transition induced by a hairpin line molecular configuration conversion
Journal of Applied Polymer Science, 2017Co-Authors: Xianwu Jing, Baogang Wang, Zhiyu HuangAbstract:A triblock copolymer, containing a polyethylene glycol (PEG) block and two symmetrical poly(2-(dimethylamino)ethyl methacrylate) (PDM) blocks, was synthesized by using PEG-based macroinitiator with copper-mediated living radical polymerization. The conductivity tests showed that the copolymer exhibited switchable responsiveness to CO2, i.e., a relatively high conductivity of solution can be switched on and off by bubbling and removing of CO2. According to the nuclear magnetic resonance results, the CO2-switchable conductivity variation could be attributed to protonation and deprotonation of tertiary amine groups in PDM blocks. Moreover, at a proper weight concentration 0.5%, the copolymer aqueous solution displayed a CO2-switchable viscosity variation. Scanning electron microscopy, cryogenic transmission electron microscopy, and dynamic light scattering characterization jointly demonstrated that the viscosity variation was the result of a CO2-switchable Vesicle-network aggregate structure transition. This structure transition can actually be attributed to a hairpin-line molecular configuration conversion in terms of the reasonable mechanism discussion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44417.
Zhiyu Huang - One of the best experts on this subject based on the ideXlab platform.
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co 2 sensitive amphiphilic triblock copolymer self assembly morphology transition and accelerating drug release from Polymeric Vesicle
Chinese Journal of Polymer Science, 2018Co-Authors: Xianwu Jing, Zhiyu Huang, Baogang WangAbstract:A series of triblock copolymers, containing a CO2-switchable block poly(2-(dimethylamino)ethyl methacrylate) (PDM) block and two symmetrical hydrophilic blocks polyacrylamide (PAM), were synthesized using atom transfer radical polymerization (ATRP) method. The pH and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO2, and the triblock copolymer aqueous solution displayed a CO2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the viscosity variation was the result of a unilamellar Vesicle-network aggregate structure transition. The release of rhodamine B from the Vesicles with and without CO2 stimuli showed the potential application in drug delivery domains; after CO2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO2-switchable morphology changes and CO2-induced drug release was proposed.
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co2 switchable Polymeric Vesicle network structure transition induced by a hairpin line molecular configuration conversion
Journal of Applied Polymer Science, 2017Co-Authors: Xianwu Jing, Baogang Wang, Zhiyu HuangAbstract:A triblock copolymer, containing a polyethylene glycol (PEG) block and two symmetrical poly(2-(dimethylamino)ethyl methacrylate) (PDM) blocks, was synthesized by using PEG-based macroinitiator with copper-mediated living radical polymerization. The conductivity tests showed that the copolymer exhibited switchable responsiveness to CO2, i.e., a relatively high conductivity of solution can be switched on and off by bubbling and removing of CO2. According to the nuclear magnetic resonance results, the CO2-switchable conductivity variation could be attributed to protonation and deprotonation of tertiary amine groups in PDM blocks. Moreover, at a proper weight concentration 0.5%, the copolymer aqueous solution displayed a CO2-switchable viscosity variation. Scanning electron microscopy, cryogenic transmission electron microscopy, and dynamic light scattering characterization jointly demonstrated that the viscosity variation was the result of a CO2-switchable Vesicle-network aggregate structure transition. This structure transition can actually be attributed to a hairpin-line molecular configuration conversion in terms of the reasonable mechanism discussion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44417.
Baogang Wang - One of the best experts on this subject based on the ideXlab platform.
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co 2 sensitive amphiphilic triblock copolymer self assembly morphology transition and accelerating drug release from Polymeric Vesicle
Chinese Journal of Polymer Science, 2018Co-Authors: Xianwu Jing, Zhiyu Huang, Baogang WangAbstract:A series of triblock copolymers, containing a CO2-switchable block poly(2-(dimethylamino)ethyl methacrylate) (PDM) block and two symmetrical hydrophilic blocks polyacrylamide (PAM), were synthesized using atom transfer radical polymerization (ATRP) method. The pH and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO2, and the triblock copolymer aqueous solution displayed a CO2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the viscosity variation was the result of a unilamellar Vesicle-network aggregate structure transition. The release of rhodamine B from the Vesicles with and without CO2 stimuli showed the potential application in drug delivery domains; after CO2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO2-switchable morphology changes and CO2-induced drug release was proposed.
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co2 switchable Polymeric Vesicle network structure transition induced by a hairpin line molecular configuration conversion
Journal of Applied Polymer Science, 2017Co-Authors: Xianwu Jing, Baogang Wang, Zhiyu HuangAbstract:A triblock copolymer, containing a polyethylene glycol (PEG) block and two symmetrical poly(2-(dimethylamino)ethyl methacrylate) (PDM) blocks, was synthesized by using PEG-based macroinitiator with copper-mediated living radical polymerization. The conductivity tests showed that the copolymer exhibited switchable responsiveness to CO2, i.e., a relatively high conductivity of solution can be switched on and off by bubbling and removing of CO2. According to the nuclear magnetic resonance results, the CO2-switchable conductivity variation could be attributed to protonation and deprotonation of tertiary amine groups in PDM blocks. Moreover, at a proper weight concentration 0.5%, the copolymer aqueous solution displayed a CO2-switchable viscosity variation. Scanning electron microscopy, cryogenic transmission electron microscopy, and dynamic light scattering characterization jointly demonstrated that the viscosity variation was the result of a CO2-switchable Vesicle-network aggregate structure transition. This structure transition can actually be attributed to a hairpin-line molecular configuration conversion in terms of the reasonable mechanism discussion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44417.