Modification with ethylenimine

Ethylenimine may be used to introduce additional sites of tryptic cleavage for protein structural studies. In this case, complete sulfhydryl modification is usually desired. Proteins are treated with ethylenimine under denaturing conditions (6-8 M guanidine hydrochloride) in the presence of a disulfide reductant to reduce any disulfide bonds before modification. Ethylenimine may be added directly to the reducing solution in excess (similar to the procedure for Aminoethyl-8 described previously) to totally modify the —SH groups formed. 

In this chapter, we review the latest advances in chitosan modification, with a special focus on the synthesis and functional properties of chitosan/poly(ethylenimine) (CP/PEI) graft copolymers and their derivatives as pDNA carriers. We also address the prospects and challenges of the practical... 

Therefore, many researchers have attempted to stabilize the PIC by additional stabilization forces. One such attempt has been the development of lipopolymers, which are produced by the introduction of hydrophobic moieties into existing polymers. The transfection efficiency of low molecular weight PEI was significantly enhanced by hydrophobic modification with cholesterol [96]. Conjugation with other lipids such as myristic acid or lauric acid also enhanced the transfection efficiency of PEI [97, 98]. The balance between the hydrophobic lipid groups and the charged ethylenimine moieties is cmcial for the stabilization of PIC in physiological solution. 

Toxicity. While many new materials are added to the adhesive chemist s arsenal, some are being removed as well. Compounds which cause health and environmental concern include ethylenimine, methylene-fcw(o-chloroan-iline) (MOCA), hexamethylene diisocyanate, formaldehyde. Some systems are no longer in use in others, modifications have been made. Thus radiation-curing technology is replacing some types of multifunctional acrylate monomers with alkoxylated compounds, because the latter are less irritating and less toxic. An example is trimethylolpropane triethoxy triacrylate. 

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