A low-viscosity epoxy resin embedding medium for electron microscopy.

Several polycations possessing substantial buffering capacity below physiological pH, such as lipopolyamines and polyamidoamine polymers, are efficient transfection agents per se--i.e., without the addition of cell targeting or membrane-disruption agents. This observation led us to test the cationic polymer polyethylenimine (PEI) for its gene-delivery potential. Indeed, every third atom of PEI is a protonable amino nitrogen atom, which makes the polymeric network an effective "proton sponge" at virtually any pH. Luciferase reporter gene transfer with this polycation into a variety of cell lines and primary cells gave results comparable to, or even better than, lipopolyamines. Cytotoxicity was low and seen only at concentrations well above those required for optimal transfection. Delivery of oligonucleotides into embryonic neurons was followed by using a fluorescent probe. Virtually all neurons showed nuclear labeling, with no toxic effects. The optimal PEI cation/anion balance for in vitro transfection is only slightly on the cationic side, which is advantageous for in vivo delivery. Indeed, intracerebral luciferase gene transfer into newborn mice gave results comparable (for a given amount of DNA) to the in vitro transfection of primary rat brain endothelial cells or chicken embryonic neurons. Together, these properties make PEI a promising vector for gene therapy and an outstanding core for the design of more sophisticated devices. Our hypothesis is that its efficiency relies on extensive lysosome buffering that protects DNA from nuclease degradation, and consequent lysosomal swelling and rupture that provide an escape mechanism for the PEI/DNA particles.

https://www.pnas.org/content/pnas/92/16/7297.full.pdf

A versatile vector for gene and oligonucleotide transfer into cells in culture and in vivo: polyethylenimine

Chitin is the most abundant natural amino polysaccharide and is estimated to be produced annually almost as much as cellulose. It has become of great interest not only as an underutilized resource, but also as a new functional material of high potential in various fields, and recent progress in chitin chemistry is quite noteworthy. The purpose of this review is to take a closer look at chitin and chitosan applications. Based on current research and existing products, some new and futuristic approaches in this fascinating area are thoroughly discussed.

A review of chitin and chitosan applications

Poly(N-isopropylacrylamide): experiment, theory and application

A statistical mechanical treatment of high polymer solutions has been carried out on the basis of an idealized model, originally proposed by Meyer, which is analogous to the one ordinarily assumed in the derivation of the ``ideal'' solution laws for molecules of equal size. There is obtained for the entropy of mixing of n solvent and N linear polymer molecules (originally disoriented), ΔS=−k[(n/β) ln v1+N ln v2] where v1 and v2 are volume fractions and β is the number of solvent molecules replaceable by a freely orienting segment of the polymer chain. This expression is similar in form to the classical expression for equal‐sized molecules, mole fractions having been replaced by volume fractions. When the disparity between the sizes of the two components is great, this expression gives entropies differing widely from the classical values, which accounts for the large deviations of high polymer solutions from ``ideal'' behavior. The entropy of disorientation of a perfectly arranged linear polymer is found t...

Thermodynamics of High Polymer Solutions

Cellular Materials Cellulose Cellulose, Biosynthesis Cellulose, Graft Copolymers Cellulose, Microcrystalline Cellulose Derivatives Cellulose Esters, Inorganic Cellulose Esters, Organic Cellulose Ethers Cement Additives Chain-Reaction Polymerization Chain Transfer Characterization of Polymers Charge-Transfer Complexes Chelate- Forming Polymers Chemical Analysis Chemically Resistant Polymers Chitin Chloroprene Polymers Chlorotrifluorethylene Polymers Chromatography Classification of Polymerization Reactions Coating Methods Coatings Coatings, Electrodeposition Cold Forming.

Encyclopedia of polymer science and engineering

VOLUME 1. Acetylenic Polymers, Substituted. Acrylamide Polymers. Acrylic (and Methacrylic) Acid Polymers. Acrylic Ester Polymers. Acrylonitrile and Acrylonitrile Polymers. Acrylonitrile-Butadiene-Styrene Polymers. Additives. Adhesion. Adhesive Compounds. Aging, Physical. Alkyd Resins. Am,ino Resins and Plastics. Antifoaming Agents. Atomic Force Microscopy. Biotechnology Applications. Bloack Copolymers. Bloack Copolymers, Ternary Triblock. Blow Molding. Chitin and Chitosan. Chromatography, Affinity. Chromatography, HPLC. Chromatography, Size Exclusion. Coating Methods, Survey. Coatings. VOLUME 2 Coextrusion. Colorants. Coloring Processes. Composites, Fabrication. Conformation and Configuration. Critical Phase Polymerizations. Cyclohexanedimethanol Polyesters. Dendronized Polymers. Dental Applications. Diacethylene and Triacethylene Polymers. Elasticity, Rubber-Like. Electronic Packaging. Electrooptical Applications. Engineering, Thermoplastics, Overview. Enzymatic Polymerization. Ethylene Polymers, Chlorosulfonated. Ethylene Polymers, HDPE. Ethylene Polymers, LDPE. Ehtylene Polymers, LLDPE. Ethylene-Acrylic Elastomers. Ethylene-Norbornene Copolymers. Extrusion. Films, Orientation. Fluorocarbon Elastomers. Fractography. Fracture. Glass Transition. Hardness. Hydrogels. Hyperbranched Polymers. VOLUME 3 Injection Molding. Inorganic Polymers. Laser Light Scattering. Light-Emiting Diodes. Lignin. Liquid Crystalline Polymers, Main-Chain. Liquid Crystalline Thermosets. Mass Spectrometry. Membrane Technology. Methacrylic Ester Polymers. Micromechanical Properties. Modeling of Polymer Processing and Properties. Nanocomposites, Polymer-Clay. Packaging, Flexible. Perfluorinated Polymers, Perfluorinated Ethylene-Propylene Copolymers. Perfluorinated Polymers Polytetrafluoroethylene. Perfluorinated Polymers Tetrafluoroethylene-Ethylene Copolymers. Perfluorinated Polymers, Tetrafluoroethylene-Perfluorinated Copolymers. Perfluorinated Polymers. Tetrafluoroethylene-Perfluorovinyl Ether Copolymers. Phosgene. Phosphorus-Containing Polymers and Oligomers. Piezoelectric Polymers. Plasticizers. Poly(3-Hydroxyalkanoates). Poly(Trimethylene Terephthalate). Polyamides, Atomatic. Polyamides, Fibers. Polyamides, Plastics. Polycyanoacrylates. Polyesters, Fibers. Polyketones. Polynucleotides. Polysulfides. VOLUME 4 Polysulfones. Polyurethanes. Pressure-Sensitive Adhesive. Reinforcement. Release Agents. Shape-Memory Polymers. Single-Site Catalysis. Stabilization. Styrene-Butadiene Rubber (SBR). Styrene Polymers. Sulfur-Containing Polymers. Surface Properties. Syndiotactic Polystyrene. Vinyl Fluoride Polymers (PVF). Vinylidene Chloride Polymers. Vinylidene Fluoride Polymers. Viscoelasticity. Weathering.

Encyclopedia of polymer science and technology

Physical Chemistry Of High Polymeric Systems

Principles of Plasticization

Über den Bau des krystallisierten Anteils der Cellulose

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