The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
David Oupický - One of the best experts on this subject based on the ideXlab platform.
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Self-immolative Polycations as gene delivery vectors and prodrugs targeting polyamine metabolism in cancer.
Molecular pharmaceutics, 2014Co-Authors: Yu Zhu, Shrey Kanvinde, Zhiyi Lin, Stuart T. Hazeldine, Rakesh K. Singh, David OupickýAbstract:Polycations are explored as carriers to deliver therapeutic nucleic acids. Polycations are conventionally pharmacological inert with the sole function of delivering therapeutic cargo. This study reports synthesis of a self-immolative Polycation (DSS-BEN) based on a polyamine analogue drug N1,N11-bisethylnorspermine (BENSpm). The Polycation was designed to function dually as a gene delivery carrier and a prodrug targeting dysregulated polyamine metabolism in cancer. Using a combination of NMR and HPLC, we confirm that the self-immolative Polycation undergoes intracellular degradation into the parent drug BENSpm. The released BENSpm depletes cellular levels of spermidine and spermine and upregulates polyamine catabolic enzymes spermine/spermidine N1-acetyltransferase (SSAT) and spermine oxidase (SMO). The synthesized Polycations form polyplexes with DNA and facilitate efficient transfection. Taking advantage of the ability of BENSpm to sensitize cancer cells to TNFα-induced apoptosis, we show that DSS-BEN e...
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Bioreducible hyperbranched poly(amido amine)s for gene delivery.
Biomacromolecules, 2009Co-Authors: Jun Chen, David OupickýAbstract:A series of reducible hyperbranched poly(amido amine)s (RHB) with high transfection efficiency were designed and synthesized as nonviral gene delivery vectors. The Polycations were synthesized by Michael addition copolymerization of N,N-dimethylaminodipropylenetriamine (DMDPTA) and two bisacrylamide monomers N,N′-hexamethylene bisacrylamide (HMBA) and N,N′-cystamine bisacrylamide (CBA). The density of disulfide linkages in the synthesized hyperbranched polymers was tuned by varying the feed molar ratio of the bisacrylamide monomers. The results demonstrate that disulfide content in RHB controls the molecular weight of the Polycation degradation products, ease of polyplex disassembly, Polycation cytotoxicity, and polyplex transfection activity. Due to their lower cytotoxicity, polyplexes based on reducible Polycations could be used safely in a wider range of DNA doses than nonreducible controls. As a result, significantly increased transfection activity is achieved with optimized formulations of reducible ...
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physical properties and in vitro transfection efficiency of gene delivery vectors based on complexes of dna with synthetic Polycations
Journal of Controlled Release, 2002Co-Authors: Tomas Reschel, David Oupický, Cestmir Koňak, Leonard W Seymour, Karel UlbrichAbstract:Biophysical properties of Polycation/DNA complexes designed for gene delivery were studied with respect to the conditions of their preparation, chemical structure and molecular weight of the Polycations involved. The Polycations used included a variety of cationic polymers and copolymers containing primary and tertiary amino or quaternary ammonium groups. It was found that the molecular weight and the size of these polyelectrolyte complexes (PECs) increase with increasing temperature and pH of the buffer. By decreasing the molecular weight of Polycations used for PEC formation, the complexes become unstable towards coagulation in aqueous solution at lower pH. The self-assembly of DNA with low-molecular-weight Polycations in water provides PECs with the lowest molecular weight, smallest size and the lowest density but their stability in NaCl solutions is very poor. Despite the complexity of the multistep transfection process, a direct correlation between the transfection efficiency in vitro and the stability of the complexes in NaCl solutions and coagulation in 0.15 M NaCl solution was found. DNA complexes with Polycations containing primary amino groups showed the best stability in saline solutions and also the best transfection activity. PECs formed by Polycations with quaternary ammonium groups were the least resistant to destruction by the added salt and provided the lowest activity in transfection assays. The highest transfection activity was found for DNA complexes formed with a statistical copolymer containing primary and tertiary amines.
Mark E. Davis - One of the best experts on this subject based on the ideXlab platform.
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Structural effects of carbohydrate-containing Polycations on gene delivery. 2. Charge center type.
Bioconjugate chemistry, 2003Co-Authors: Theresa M. Reineke, Mark E. DavisAbstract:Recent Polycation structure−gene delivery studies reveal that subtle changes in the molecular structure of Polycations have substantial influences on DNA-binding and condensation and on in vitro toxicity and gene delivery efficiency. In Part 1 of this structure−property study using carbohydrate-containing Polycations (1), it is demonstrated that as the amidine charge center is removed further from the carbohydrate unit within the Polycation structure, the toxicity increases. Inclusion of larger carbohydrate species within the Polycation backbone also reduces the toxicity. Here, the effect that Polycation charge center type has on toxicity and gene delivery efficiency is investigated. A series of quaternary ammonium Polycations containing N,N,N‘,N‘-tetramethyl-1,6-hexanediamine, d-trehalose, and β-cyclodextrin are synthesized in order to elucidate the effects of charge center type (by comparison to the data given in Part 1) on gene delivery. In all cases, it is found that the quaternary ammonium analogues exhibit lower gene expression values and similar toxicities to their amidine analogues. Additionally, transfection experiments conducted in the presence of chloroquine reveal increased gene expression from quaternary ammonium containing Polycations and not from their amidine analogues.
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Structural effects of carbohydrate-containing Polycations on gene delivery. 3. Cyclodextrin type and functionalization.
Bioconjugate chemistry, 2003Co-Authors: Stephen R. Popielarski, Swaroop Mishra, Mark E. DavisAbstract:Linear cationic β-cyclodextrin (β-CD)-based polymers can form polyplexes with plasmid DNA and transfect cultured cells. The effectiveness of the gene delivery and the cellular toxicity has been related to structural features in these Polycations. Previous β-CD Polycations were prepared from the cocondensation of 6^A,6^D-dideoxy-6^A,6^D-diamino-β-CD monomers with other difunctionalized monomers such as dimethyl suberimidate (DMS). Here, the type of CD and its functionalization are varied by synthesizing numerous 3^A,3^B-dideoxy-3^A,3^B-diamino-β- and γ-CD monomers. Both alkyl- and alkoxydiamines are prepared in order to vary the nature of the spacing between the CD and the primary amines in the monomers. These diamino-CD-monomers are polymerized with DMS to yield amidine-based Polycations. The nature of the spacer between the CD-ring and the primary amines of each monomer is found to influence both molecular weight and polydispersity of the Polycations. When these Polycations are used to form polyplexes with plasmid DNA, longer alkyl regions between the CD and the charge centers in the Polycation backbone increase transfection efficiency and toxicity in BHK-21 cells, while increasing hydrophilicity of the spacer (alkoxy versus alkyl) provides for lower toxicity. Further, γ-CD-based Polycations are shown to be less toxic than otherwise identical β-CD-based Polycations.
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development of a nonviral gene delivery vehicle for systemic application
Bioconjugate Chemistry, 2002Co-Authors: Suzie H Pun, Mark E. DavisAbstract:Polycation vehicles used for in vitro gene delivery require alteration for successful application in vivo. Modification of Polycations by direct grafting of additional components, e.g., poly(ethylene glycol) (PEG), either before or after DNA complexation, tend to interfere with polymer/DNA binding interactions; this is a particular problem for short Polycations such as linear, β-cyclodextrin-containing Polycations (βCDPs). Here, a new method of βCDP polyplex (Polycation/DNA composite structures) modification is presented that exploits the ability to form inclusion complexes between cyclodextrins and adamantane. Surface-PEGylated βCDP polyplexes are formed by self-assembly of the polyplexes with adamantane−PEG conjugates. While unmodified polyplexes rapidly aggregate and precipitate in salt solutions, the PEGylated βCDP polyplexes are stable at conditions of physiological salt concentration. Addition of targeting ligands to the adamantane−PEG conjugates allows for receptor-mediated delivery; galactosylated βCDP-based particles reveal selective targeting to hepatocytes via the asialoglycoprotein receptor. Galactosylated particles transfect hepatoma cells with 10-fold higher efficiency than glucosylated particles (control), but show no preferential transfection in a cell line lacking the asialoglycoprotein receptor. Thus, surface modification of βCDP-based polyplexes through the use of cyclodextrin/adamantane host/guest interactions endows the particles with properties appropriate for systemic application.
Yadong Wang - One of the best experts on this subject based on the ideXlab platform.
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Polycations and their biomedical applications
Progress in Polymer Science, 2016Co-Authors: Kyobum Kim, William C.w. Chen, Yunhoe Heo, Yadong WangAbstract:Abstract Polycations are useful delivery vehicles for nucleic acids and proteins. Physicochemical properties, safety, and cost are important design parameters for Polycation-enabled controlled release methods. Improvements in the design and biocompatibility of synthetic Polycations and complexes thereof are necessary for clinical applications. This review focuses on breakthroughs in the development of biocompatible Polycations and their biomedical applications in the past 10 years. First, we summarize current strategies to develop naturally derived and synthetic Polycations and describe the most commonly used Polycations. Second, we discuss Polycation-mediated non-viral gene delivery systems used for tissue engineering and regenerative medicine. Third, we review the development of Polycation-mediated self-assembled systems for the delivery of heparin-binding proteins, with an emphasis on translational potential. Finally, we introduce platforms for fabricating Polycation-based complexes, including layer-by-layer assembly, polymeric vesicles, Polycation-containing microspheres, and approaches to improve the functionality of delivery complexes. With improvements in Polycation design, safety, and efficacy, Polycation-based controlled delivery is expected to contribute significantly to tissue repair and regeneration applications.
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A Biocompatible Arginine-Based Polycation
Advanced Functional Materials, 2010Co-Authors: Blaine J. Zern, Adeboye O. Osunkoya, Yadong WangAbstract:Self assembly between cations and anions is ubiquitous throughout nature. Important biological structures such as chromatin often use polyvalent assembly between a Polycation and a polyaninon. Biomedical importance of synthetic Polycations arises from their affinity to polyanions such as nucleic acid and heparan sulfate. However, the limited biocompatibility of synthetic Polycations hampers the realization of their immense potential. By examining biocompatible cationic peptides, we hypothesize that a biocompatible Polycation should be biodegradable and made from endogenous cations. We designed an arginine-based biodegradable Polycation and demonstrated that it was orders of magnitude more compatible than conventional Polycations in vitro and in vivo. This biocompatibility diminishes when L-arginine is substituted with D-arginine or when the biodegradable ester linker changes to a biostable ether linker. We believe this design can lead to many biocompatible Polycations that can significantly advance a wide range of applications including controlled release, tissue engineering, biosensing, and medical devices.
Arthi Jayaraman - One of the best experts on this subject based on the ideXlab platform.
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Molecular simulations of Polycation-DNA binding exploring the effect of peptide chemistry and sequence in nuclear localization sequence based Polycations.
The journal of physical chemistry. B, 2013Co-Authors: Robert M. Elder, Arthi JayaramanAbstract:Gene therapy relies on the delivery of DNA into cells, and Polycations are one class of vectors enabling efficient DNA delivery. Nuclear localization sequences (NLS), cationic oligopeptides that target molecules for nuclear entry, can be incorporated into Polycations to improve their gene delivery efficiency. We use simulations to study the effect of peptide chemistry and sequence on the DNA-binding behavior of NLS-grafted Polycations by systematically mutating the residues in the grafts, which are based on the SV40 NLS (peptide sequence PKKKRKV). Replacing arginine (R) with lysine (K) reduces binding strength by eliminating arginine–DNA interactions, but placing R in a less hindered location (e.g., farther from the grafting point to the Polycation backbone) has surprisingly little effect on Polycation–DNA binding strength. Changing the positions of the hydrophobic proline (P) and valine (V) residues relative to the Polycation backbone changes hydrophobic aggregation within the Polycation and, consequentl...
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Coarse-Grained Simulation Studies of Effects of Polycation Architecture on Structure of the Polycation and Polycation–Polyanion Complexes
Macromolecules, 2012Co-Authors: Robert M. Elder, Arthi JayaramanAbstract:Polycations are a promising class of nonviral DNA delivery agents that bind to negatively charged DNA and transfect the DNA into target cells. The architecture and chemistry of the Polycation strongly affect Polycation–DNA complexation and in turn the ability of Polycations to transfect DNA into cells. Here we develop coarse-grained models and conduct Langevin dynamics simulations to understand how the architecture of lysine-based Polycations affects their complexation with DNA-like polyanions. We first characterize the structure of linear polylysine and oligolysines grafted to a polyolefin backbone and then the structure of complexes (termed polyplexes) formed by these Polycations with polyanions of varying flexibility. We find that increasing oligolysine graft length and decreasing graft spacing both increase the size and rigidity of the grafted oligolysines, although they remain less rigid than semiflexible linear polylysine. Increasing ionic strength or counterion valency reduces Polycation size and m...
G. J. J. C. Boonen - One of the best experts on this subject based on the ideXlab platform.
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Cytochalasin B-induced superoxide production in Polycation-treated neutrophils
Inflammation, 1991Co-Authors: Jan G.r. Elferink, B. M. Koster, G. J. J. C. BoonenAbstract:Cytochalasin B alone induces little superoxide production in intact rabbit peritoneal neutrophils. The cytochalasin causes a strong production of superoxide in cells treated with membrane-permeabilizing Polycations. Several Polycations were able to express the activating effect of cytochalasin B. Especially the poly- l -arginine with a molecular weight of 24,000 proved to be effective. The effectiveness of some Polycations is limited because they inactivate the superoxide-generating oxidase system of the neutrophil. Cytochalasin B-induced superoxide production starts at poly l -arginine concentrations that cause a change of membrane permeability. At the concentrations of cytochalasin B used in our experiments, the binding of [^3H]cytochalasin B is not enhanced in poly- l -arginine-treated cells as compared with control cells. Activation of superoxide production by cytochalasin B in Polycation-treated neutrophils occurs both in the presence or absence of extracellular Ca^2+. When the cells are pretreated with agents that known to interfere with intracellular Ca^2+, the subsequent activation is strongly inhibited, suggesting a role for intracellular Ca^2+ in cytochalasin B-induced activation. It is suggested that cytochalasin B alone is not able to activate all the steps that eventually result in complete activation of the superoxide-generating oxidase and that membrane perturbation by Polycation provides activation of the remaining steps.
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Cytochalasin B-induced superoxide production in Polycation-treated neutrophils
Inflammation, 1991Co-Authors: Jan G.r. Elferink, B. M. Koster, G. J. J. C. BoonenAbstract:Cytochalasin B alone induces little superoxide production in intact rabbit peritoneal neutrophils. The cytochalasin causes a strong production of superoxide in cells treated with membrane-permeabilizing Polycations. Several Polycations were able to express the activating effect of cytochalasin B. Especially the poly- l -arginine with a molecular weight of 24,000 proved to be effective. The effectiveness of some Polycations is limited because they inactivate the superoxide-generating oxidase system of the neutrophil. Cytochalasin B-induced superoxide production starts at poly l -arginine concentrations that cause a change of membrane permeability. At the concentrations of cytochalasin B used in our experiments, the binding of [^3H]cytochalasin B is not enhanced in poly- l -arginine-treated cells as compared with control cells. Activation of superoxide production by cytochalasin B in Polycation-treated neutrophils occurs both in the presence or absence of extracellular Ca^2+. When the cells are pretreated with agents that known to interfere with intracellular Ca^2+, the subsequent activation is strongly inhibited, suggesting a role for intracellular Ca^2+ in cytochalasin B-induced activation. It is suggested that cytochalasin B alone is not able to activate all the steps that eventually result in complete activation of the superoxide-generating oxidase and that membrane perturbation by Polycation provides activation of the remaining steps.
