Topic
Cationic polymerization
About: Cationic polymerization is a research topic. Over the lifetime, 32794 publications have been published within this topic receiving 572231 citations.
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TL;DR: This work focuses on the characterization of the phytochemical components of Lactide ROP and their role in the regulation of cell reprograming.
Abstract: 23 Stereocontrol of Lactide ROP 6164 231 Isotactic Polylactides 6164 232 Syndiotactic Polylactides 6166 233 Heterotactic Polylactides 6166 3 Anionic Polymerization 6166 4 Nucleophilic Polymerization 6168 41 Mechanistic Considerations 6168 42 Catalysts 6169 421 Enzymes 6169 422 Organocatalysts 6169 43 Stereocontrol of Lactide ROP 6170 44 Depolymerization 6170 5 Cationic Polymerization 6170 6 Conclusion and Perspectives 6171 7 Acknowledgments 6173 8 References and Notes 6173
2,014 citations
TL;DR: Concentration-dependent lysis mediated by initial electrostatic binding was observed in dye release studies using lipid vesicles, providing the probable mechanism for observed toxicity with the cationic MMPCs.
1,471 citations
TL;DR: The studies reported here examine the effects of some systematic chemical structural changes in both the cationic lipid components and the neutral phospholipid requirements for transfection activity in COS.
1,467 citations
TL;DR: Optical microscopy revealed that the LalphaC complexes bind stably to anionic vesicles (models of cellular membranes), whereas the more transfectant HIIC complexes are unstable and rapidly fuse and release DNA upon adhering to anionics.
Abstract: A two-dimensional columnar phase in mixtures of DNA complexed with cationic liposomes has been found in the lipid composition regime known to be significantly more efficient at transfecting mammalian cells in culture compared to the lamellar (LalphaC) structure of cationic liposome-DNA complexes. The structure, derived from synchrotron x-ray diffraction, consists of DNA coated by cationic lipid monolayers and arranged on a two-dimensional hexagonal lattice (HIIC). Two membrane-altering pathways induce the LalphaC --> HIIC transition: one where the spontaneous curvature of the lipid monolayer is driven negative, and another where the membrane bending rigidity is lowered with a new class of helper-lipids. Optical microscopy revealed that the LalphaC complexes bind stably to anionic vesicles (models of cellular membranes), whereas the more transfectant HIIC complexes are unstable and rapidly fuse and release DNA upon adhering to anionic vesicles.
1,202 citations
TL;DR: It is proposed that after the cationic lipid/DNA complex is internalized into cells by endocytosis it destabilization induces flip-flop of anionic lipids from the cytoplasmic-facing monolayer, which laterally diffuse into the complex and form a charge neutral ion pair with the cationsic lipids.
Abstract: To understand how DNA is released from cationic liposome/DNA complexes in cells, we investigated which biomolecules mediate release of DNA from a complex with cationic liposomes. Release from monovalent[1,2-dioleoyl-3(1)-1(trimethylammonio)propane] or multivalent (dioctadecylamidoglycylspermine) lipids was quantified by an increase of ethidium bromide (EtBr) fluorescence. Plasmid sensitivity to DNAse I degradation was examined using changes in plasmid migration on agarose gel electrophoresis. Physical separation of the DNA from the cationic lipid was confirmed and quantified on sucrose density gradients. Anionic liposomes containing compositions that mimic the cytoplasmic-facing monolayer of the plasma membrane (e.g. phosphatidylserine) rapidly released DNA from the complex. Release occurred near a 1/1 charge ratio (-/+) and was unaffected by ionic strength or ion type. Water soluble molecules with a high negative linear charge density such as dextran sulfate or heparin also released DNA. However, ionic water soluble molecules such as ATP, tRNA, DNA, poly(glutamic acid), spermidine, spermine, or histone did not, even at 100-fold charge excess (-/+). On the basis of these results, we propose that after the cationic lipid/DNA complex is internalized into cells by endocytosis it destabilizes the endosomal membrane. Destabilization induces flip-flop of anionic lipids from the cytoplasmic-facing monolayer, which laterally diffuse into the complex and form a charge neutral ion pair with the cationic lipids. This results in displacement of the DNA from the cationic lipid and release of the DNA into cytoplasm. This mechanism accounts for a variety of observations on cationic lipid/DNA complex-cell interactions.
1,154 citations