Degradation, cationic

Kwon YJ, Standley SM, Goh SL et al (2005) Enhanced antigen presentation and immunosti-mulation of dendritic cells using acid-degradable cationic nanoparticles. J Control Release 105 199-212... 

Giolando, S.T., R.A. Rapaport, R. J. Larson, T.W. Federle, M. Stalmans, and P. Mascheleyn. 1995. Environmental fate and effects of DEEDMAC a new rapidly degradable cationic surfactant for use in fabric softeners. Chemosphere 30, 1067-1083. 

Anderson, D. G., Lynn, D. M., and Langer, R. (2003) Semi-automated synthesis and screening of a large library of degradable cationic polymers for gene delivery. 

Non viral gene delivery still suffers from limited in vivo applications due to a poor vector efficacy to deliver the gene at the target. Works on DNA delivery involve different types of cationic lipids (1, 2) or polymers (3) and degradable cationic lipid/DNA complexes (4, 5) or polymer/DNA complexes (6). 

If the early endosomal release is not possible, another way to keep DNA intact in lysosome is to protect the DNA from lysosomal degradation. Cationic liposomes formulated with cholesterol believed to offer a useful role in keeping DNA intact (121,156,157). Straub-inger et al. (158) have demonstrated that the lysosomal enzymes work at lower pH, i.e., pH < 6. It was also shown that cholesterol-containing liposomes, which possess greater stability and lower ion-permeability compared with DOPE-containing liposomes, provide an improved stability to the lipid-DNA complex in the cytosol (158-160). It is easily conceivable that if the endosomal content passes onto lysosome before being released from endosomes, the lipid/DNA complex could remain secured in the lysosome. 

Another difficulty is that only a small part of problem waste contains cations or well sorbed matter. Reactor waste often contains radioactive isotopes in the form of anions, which in substance are not adsorbed. In waste waters of chemical factories is also present unabsorbable matter and also ligands, which may form with cations complex compounds strongly degrading cation adsorption. One more consequence of adsorption and retardation is that a water horizon contaminated with adsorbed matter is very difficult to clean up and remove pollutants from it. 

I. Ko, A. Ziady, S. Lu, Y. Kwon, Acid-degradable cationic methacrylamide polymerized in the presence of plasmid DNA as tunable non-viral gene carrier. Biomaterials 29 (2008) 3872-3881. 

Ding M, Zeng X, He X, Li J, Tan H, Fu Q. Cell intemalizable and intracellularly degradable cationic polyurethane micelles as a potential platform for efficient imaging and drug delivery. Biomacromolecules 2014 15 2896-906. 

In a combinatorial approach, Anderson et al. [116] synthesized 2350 structurally unique, degradable cationic polymers. The synthesis was based on Michael addition of various primary amines or secondary di-amines with a variety of di-acrylates in DMSO. Without further purification, a large-scale transfection screen was performed, identifying candidates with interesting gene transfer properties. 

Others would include the addition of materials aimed at increa sing the bioavailabiUty of the contaminant to the degrading organisms. The most studied compounds are surfactants, but cations have been reported to increase the bioavailabiUty of some organic compounds, and sorbents and clays are also considered. The dispersion of spilled oil on water by the appHcation of dispersants is perhaps the major commercial use of this idea. 

If either dry powders or inverse emulsions are not properly mixed with water, large lumps of polymer form that do not dissolve. This not only wastes material, but can also cause downstream problems. This is especially tme for paper where visible defects may be formed. Specialized equipment for dissolving both dry polymers and inverse emulsions on a continuous basis is available (22,23). Some care must be taken with regard to water quaUty when dissolving polyacrylamides. Anionic polymers can degrade rapidly in the presence of ferrous ion sometimes present in well water (24). Some cationic polymers can lose charge by hydrolysis at high pH (25). 

Methyl Isopropenyl Ketone. Methyl isopropenyl ketone [814-78-8] (3-methyl-3-buten-2-one) is a colorless, lachrymatory Hquid, which like methyl vinyl ketone readily polymerizes on exposure to heat and light. Methyl isopropenyl ketone is produced by the condensation of methyl ethyl ketone and formaldehyde over an acid cation-exchange resin at 130°C and 1.5 MPa (218 psi) (274). Other methods are possible (275—280). Methyl isopropenyl ketone can be used as a comonomer which promotes photochemical degradation in polymeric materials. It is commercially available in North America (281). 

Metal carboxyiates have been considered as nucleophilic agents capable of removing aHyUc chlorine and thereby affording stabilization (143). Typical PVC stabilizers, eg, tin, lead, or cadmium esters, actually promote the degradation of VDC polymers. The metal cations in these compounds are much too acidic to be used with VDC polymers. An effective carboxylate stabilizer must contain a metal cation sufftcientiy acidic to interact with aHyUc chlorine and to facihtate its displacement by the carboxylate anion, but at the same time not acidic enough to strip chlorine from the polymer main chain (144). 

Physical Chemical Characterization. Thiamine, its derivatives, and its degradation products have been fully characterized by spectroscopic methods (9,10). The ultraviolet spectmm of thiamine shows pH-dependent maxima (11). H, and nuclear magnetic resonance spectra show protonation occurs at the 1-nitrogen, and not the 4-amino position (12—14). The H spectmm in D2O shows no resonance for the thiazole 2-hydrogen, as this is acidic and readily exchanged via formation of the thiazole yUd (13) an important intermediate in the biochemical functions of thiamine. Recent work has revised the piC values for the two ionization reactions to 4.8 and 18 respectively (9,10,15). The mass spectmm of thiamine hydrochloride shows no molecular ion under standard electron impact ionization conditions, but fast atom bombardment and chemical ionization allow observation of both an intense peak for the patent cation and its major fragmentation ion, the pyrimidinylmethyl cation (16). 

X-ray diffraction patterns yield typical 1.2—1.4 nm basal spacings for smectite partially hydrated in an ordinary laboratory atmosphere. Solvating smectite in ethylene glycol expands the spacing to 1.7 nm, and beating to 550°C collapses it to 1.0 nm. Certain micaceous clay minerals from which part of the metallic interlayer cations of the smectites has been stripped or degraded, and replaced by expand similarly. Treatment with strong solutions of... 

TBT exists in solution as a large univalent cation and forms a neutral complex with CH or OH . It is extremely surface active and so is readily adsorbed onto suspended particulate material. Such adsorption and deposition to the sediments limits its lifetime in the water column. Degradation, via photochemical reactions... 

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