Molecular weight polyethylenimines

Lu B, Xu X-D, Zhang X-Z et al (2008) Low molecular weight polyethylenimine grafted N-maleated chitosan for gene delivery properties and in vitro transfection studies. Biomacromolecules 9(10) 2594—2600... 

Gosselin MA, Guo W, Lee RJ (2001) Efficient gene transfer using reversibly cross-linked low molecular weight polyethylenimine. Bioconjug Chem 12 989-994... 

More recently, composite membranes have been made by interfacial polymerization or by in situ polymerization A representative case is illustrated in F. 8. Here, a microporous polysulfone membrane is used as a substrate. This membrane is soaked in a dilute aqueous solution of a low molecular weight polyethylenimine (PEI). Without drying, this membrane is then contacted with a crosslinking agent such as toluene diisocyanate (TDI) or isophthaloyl chloride dissolved in hexane, after which the membrane is cured in an oven. A highly crosslinked, salt-rejecting interfacial layer is formed in this way. A summary of the properties of three of the more important composite membranes is presented in Table 10. 

Kunath K, et al. (2003). Low-molecular-weight polyethylenimine as a non-viral vector for DNA delivery Comparison of physicochemical properties, transfection efflciency and in vivo distribution with high-molecular-weight polyethylenimine. J. Control. Rel. 89 113-125. 

Petersen, H., Kunath, K., Martin, A.L., Stolnik, S., Roberts, C.J., Davies, M.C., et al. Starshaped poly(ethylene gJycol)-block-polyethylenimine copolymers enhance DNA condensation of low molecular weight polyethylenimines. Biomacromolecules 3, 926-936 (2002)... 

Lu B, Sun Y, Li Y et al (2009) N-succinyl-chitosan grafted with low molecular weight polyethylenimine as a serum-resistant gene vector. Mol Biosyst 5 629-637... 

The hydrolyses of ADP and ATP were tried in the presence of low-molecular-weight analogs of polyethylenimine, i e. ethylenediamine, 77 (ED), diethylenetriamine, 78 (DT), triethylenetetramine, 79 (TT), tetraethylenepentamine, 80 (TP) and pentaethylenehexamine129). These compounds accelerated the reaction several times. The degree of the acceleration increased with increasing degree of polymerization. 

The other possibility is to coat the silica with a polymer of defined properties (molecular weight and distribntion) and olefin groups, e.g., polybutadiene, and cross-linked either by radiation or with a radical starter dissolved in the polymer [32]. This method is preferentially used when other carriers like titania and zirconia have to be surface modified. Polyethylenimine has been cross-linked at the snrface with pentaerythrolglycidether [41] to yield phases for protein and peptide chromatography. Polysiloxanes can be thermally bonded to the silica surface. Other technologies developed in coating fnsed silica capillaries in GC (polysiloxanes with SiH bonds) can also be applied to prepare RP for HPLC. 

Fischer, D., Bieber, T., Li, Y., Elsasser, H-P, Kissel, T. (1999). A novel non-viral vector for DNA delivery based on low molecular weight, branched polyethylenimine effect of molecular weight on transfection efficiency and cytotoxicity. Pharm. Res., 16, 1273-12791. 

Polymer type Polyethylenimine hydrophilic block Polyamidoamine low molecular weight low charge density Polymethacrylates low [particles] ... 

Werth S, Urban-Klein B, Dai L, Hdbel S, Grzelinski M, Bakowsky U, Czubayko F, Aigner A (2006) A low molecular weight fraction of polyethylenimine (PEI) displays increased transfection efficiency of DNA and siRNA in fresh or lyophilized complexes. J Control Release 112(2) 257-270... 

Peng Q, Hu C, Cheng J et al (2009) Influence of disulfide density and molecular weight on disulfide cross-linked polyethylenimine as gene vectors. Bioconjug Chem 20 340-346... 

Peng Q, Zhong Z, Zhuo R (2008) Disulfide cross-linked polyethylenimines (PEI) prepared via thiolation of low molecular weight PEI as highly efficient gene vectors. Bioconjug Chem 19 499-506... 

Water-soluble polyethylenimine of molecular weight 30,000 has been used for the synthesis of a model tetrapeptide by Blecher and Pfaender 161). The /V-carboxyanhy-dride method was used for the coupling, and by ultrafiltration excess reagents were removed. An enzymatic method was employed in this case for the splitting of the peptide from the support. 

Yang,T., Hussain, A., Bai, S., Khalil, I. A., Harashima, H., and Ahsan, F. (2006), Positively charged polyethylenimines enhance nasal absorption of the negatively charged drug, low molecular weight heparin, J. Controlled Release, 115,289-297. 

Blecher and Pfaender used polyethylenimine (PEI) of molecular weight 30000 as a water-soluble support for the synthesis of a model tetrapeptide This polymer is designed for use in combination with the N-carboxyanhydride coupling method. 

It was reported that a series of linear polyethylenimines (PEIs) with various molecular weights were synthesized and used to prepare polypseudorotaxanes with a-CD [81]. The PEIs were found to form stable polypseudorotaxanes at suitable pH and/or temperature, because PEIs have ionizable secondary amino groups pK = 8.9), which play a role of an energy barrier for the polypseudorotaxane formation. 

Polymer beads may be modified by addition of a liquid such as Apiezon L (high molecular weight hydrocarbons) the effect of this is apparently not to alter the selectivity of the packing but only to reduce retention times. Some tailing is observed with ammonia and amines, and improvement in performance of these compounds had been obtained by addition of tetraethylenepentamine or polyethylenimine. 

Polyethylenimine is a product of the self-condensation of the strained-ring compound ethylenimine (aziridine, azacyclopropane). It is a globular molecule having a not quite statistical distribution of amine groups (30% primary, 40% secondary and 30% tertiary amine). The most effective molecular weight range for this water-soluble polymer in composite membrane fabrication has been 10,000 to 60,000. 

A series of Comb-burst polyethylenimine was thus synthesized with a side-chain DP increasing from 10 to 20 for the first two generations, and then maintained constant at 100 for the subsequent generations [106], A geometric increase in molecular weight was observed as predicted by Equation 30.12, with grafting yield variations similar to those observed for arborescent systems. 

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