Self-assembling Polysaccharide Polyelectrolytes
Zusammenfassung der Projektergebnisse
In order to implement photoactivity into polysaccharides, highly engineered photoactive polysaccharide derivatives were synthesized applying modern esterification techniques. Namely cellulose, dextran and pullulan were functionalized with fluorescent photocrosslinkable coumarin-type chromophore by the activation of the carboxylic acid with N,N-carbonyldiimidazole (CDI). Moreover, ionic functionalities were linked to the polymer by the introduction of sulfuric acid half esters or the esterification with a cationic carboxylic acid derivative. The reactions reported demonstrate an efficient path to obtain highly functionalized photoactive polysaccharide derivatives and to prepare multifunctional derivatives thereof. It is important to emphasize that the reaction conditions applied for the second functionalization preserve the photochemical moieties. The 2π+2π cycloaddition and the corresponding cycloreversion of the coumarin type moieties linked to the polysaccharide were shown in solution by UV-Vis spectroscopy. It was also demonstrated that the solution properties, namely the viscosity, can be controlled by this photodimerization although it was not possible to give a definitive explanation of the effects observed. Based on the new polymers synthesized, namely with N,N-(dialkylamino)ethyl dextrans it could be shown that the design of the structure of the polysaccharide derivatives in particular the hydrophobic/hydrophilic balance strongly effects the charge regulated self-assembly in polysaccharide based materials. Thus, it was demonstrated that N,N-(dialkylamino)ethyl dextrans can dewater an initially hydrated substrate up to 50% depending on their particular structure. Beyond the project relevant issues different promising findings were made. First it turned out that the photoactive polysaccharide esters are suitable for the preparation of nano-scaled particles whose properties might be controllable by light. Second some compounds synthesized during the project are applicable as non-viral carrier systems for nucleic acid delivery.
Projektbezogene Publikationen (Auswahl)
-
“Efficient Synthesis and Characterization of New Photoactive Dextran Esters Showing Nanosphere Formation”. Macromolecular Bioscience (2008) 8, 606-614
H. Wondraczek, T. Heinze
-
“Surface Plasmon Resonance Studies of Pullulan and Pullulan Cinnamate Adsorption onto Cellulose”. Biomacromolecules ( 2009) 10, 2451-2459
A. Kaya, X. Du, Z. Liu, J. W. Lu, J. R. Morris, W. G. Glasser, Th. Heinze, A. R. Esker
-
“Photocrosslinkable Polysaccharide Sulfates”. European Polymer Journal (2010) 46, 1688-1695
H. Wondraczek, A. Pfeifer, T. Heinze
-
“Synthesis of highly functionalized dextran alkyl carbonates showing nanosphere formation”. Carbohydrate Polymers (2011) 83, 1112-1118
H. Wondraczek, T. Elschner, T. Heinze
-
“Enhanced Dewatering of Polyelectrolyte Nanocomposites by Hydrophobic Polyelectrolytes”. Langmuir (2012) 28, 11086-11094
J. Kittle, H. Wondraczek, C. Wang, F. Jiang, M. Roman, Th. Heinze, A. Esker
-
“Water soluble photoactive cellulose derivatives: synthesis and characterization of mixed 2-[(4-methyl-2-oxo-2Hchromen-7-yl)oxy]acetic acid-(3-carboxypropyl)trimethylammonium chloride esters of cellulose”. Cellulose (2012) 19, 1327-1335
H. Wondraczek, A. Pfeifer, T. Heinze
