Polyethylenimine properties

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. 

The modified polyethylenimines described so far are only a few of many possibilities. It is obvious that this polymer provides a remarkably versatile macromolecular matrix for the attachment of a wide variety of different types of functional groups. Furthermore, the polymer framework makes it possible to juxtapose a binding site, a catalytic group, and an apolar-aqueous interface in a locally compact array. Thus a wide range of local environments can be created on this macromolecular water-soluble catalyst. We hope to be able to exploit these to obtain a series of synthetic macromolecules with tailor-made catalytic properties. 

Ferrari, S., Pettenazzo, A., Garbati, N., Zacchello, F., Behr, J.P., Scarpa, M. (1999). Polyethylenimine shows properties of interest for cystic fibrosis gene therapy. Bio-... 

Erbacher, P., Bettinger, T., Belguise-Valladier, P., Zou, S., Coll, J.L., Behr, J.P. et al (1999) Transfection and physical properties of various saccharide, poly(ethylene glycol) and antibody-derivatized polyethylenimines (PEI). J. Gene Med., 1,210-222. 

Abstract Carbohydrates have been investigated and developed as delivery vehicles for shuttling nucleic acids into cells. In this review, we present the state of the art in carbohydrate-based polymeric vehicles for nucleic acid delivery, with the focus on the recent successes in preclinical models, both in vitro and in vivo. Polymeric scaffolds based on the natural polysaccharides chitosan, hyaluronan, pullulan, dextran, and schizophyllan each have unique properties and potential for modification, and these results are discussed with the focus on facile synthetic routes and favorable performance in biological systems. Many of these carbohydrates have been used to develop alternative types of biomaterials for nucleic acid delivery to typical polyplexes, and these novel materials are discussed. Also presented are polymeric vehicles that incorporate copolymerized carbohydrates into polymer backbones based on polyethylenimine and polylysine and their effect on transfection and biocompatibility. Unique scaffolds, such as clusters and polymers based on cyclodextrin (CD), are also discussed, with the focus on recent successes in vivo and in the clinic. These results are presented with the emphasis on the role of carbohydrate and charge on transfection. Use of carbohydrates as molecular recognition ligands for cell-type specific dehvery is also briefly... 

Koping-Hoggard M, Tubulekas I, Guan H, Edwards K, Nilsson M, Varum KM, Artursson P (2001) Chitosan as a nonviral gene delivery system. Structure-property relationships and characteristics compared with polyethylenimine in vitro and after lung administration in vivo. Gene Ther 8 1108-1121... 

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... 

Rao GA, Tsai R, Roura D et al (2008) Evaluation of the transfection property of a peptide ligand for the fibroblast growth factor receptor as part of PEGylated polyethylenimine polyplex. J Drug Target 16 79-89... 

Synthetic polymer. Among the cationic synthetic polymers used for gene delivery are polyethylenimine (PEI), polyamidoamine dendrimers, and poly(2-dimethylaminoethyl methacrylate).161-164 Depending on the flexibility (or rigidity) of the polymers, they form either a small (<100 nm) DNA polyplex or a large (>1 to 10 pm) DNA polyplex.165 More detailed physicochemical properties and their transfection efficacy are to be discussed. 

Lin J, Qiu SY, Lewis K et al. (2002) Bactericidal properties of flat surfaces and nanoparticles derivatized with alkylated polyethylenimines. Biotechnol Prog 18 1082-1086... 

Table 3.3 Properties of polyethylenimines with covalently-linked aminopyridines.

The last few decades has seen substantial progress in the fabrication of synthetic polymers with biocatalytic properties. A range of polymers has been examined as structural frameworks for the attachment of catalytic groups. For homogeneous catalysts, highly branched polyethylenimines have proved particularly versatile. Modified polystyrenes have served well as foundations for heterogeneous catalysts. 

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. 

Another approach used for deactivating part of the amine groups of polyethylenimine was to use a partial quaternization of polyethylenimine with ethyl iodide. The membranes formed were similar in properties to those made by the partial polyethylenimine neutralization. Still another type of amine polymer was prepared by free radical polymerization of a mixture of diallylamine hydrochloride, dimethyl diallyl ammonium chloride and sulfur dioxide. This polymer in the free base form for interfacial reaction had reactive secondary amine groups and non-reactive quaternary amine groups ... 

The membranes formed were similar in properties to the modified polyethylenimine types. 

Radeva, T. and Petkanchin, I., Electric properties and conformation of polyethylenimine at the hematite-aqueous solution interface, J. Colloid Intetf. Sci., 196, 87,1997. Ozaki, M., Kratohvil, S., and Matijevic, E., Eormation of monodispersed spindle-type hematite particles, 7. Colloid Interf. Sci., 102, 146, 1984. 

Meszaros, R. et al.. Adsorption and electrokinetic properties of polyethylenimine on silica surfaces, Langmuir, 18, 6164, 2002. 

Branched polyethylenimine (BPEI) is a strong polybase even at high ionic strength [79, 80] and forms complexes with acids. Its behavior is determined by properties such as the branched structure, presence of three different types of amine groups, strong neighboring interactions between various amine groups, and the compact structure in aqueous solution. 

Skachkova AL, Golub TP, Sidorova MP, Omarova KI, Musabekov KB. Elec-trokinetic and adsorption properties of Si02 in OP-7 and polyethylenimine solutions. Colloid J 1991 53 1100-1105. 

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. 

Whilst there is a rich area of chemical space for investigation of PAIs as illustrated in Scheme 2.1, research has mostly concentrated on the simplest congener of this group of polymers, namely polyethylenimine (PEI). PEI has some, apparently unique, properties that the other members of this family lack, albeit that there might be other PAIs with evenly good, or even better, properties that have simply not been investigated to date. A recurring theme of this chapter will be the vast areas of chemical space of PAIs that has been unexplored, especially for biomedical applications. 

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