Cationic cellulose and other polysaccharide derivatives are attractive targets for biomedical applications due to their propensity for electrostatically binding with anionic biomolecules, such as nucleic acids and certain proteins. However, relatively few practical synthetic methods have been described for their preparation. Herein, we report a useful and efficient strategy for cationic polysaccharide salt preparation by reaction of 6-bromo-6-deoxycellulose esters or 6-bromo-6-deoxy-curdlan with pyridine or 1-methylimidazole exclusively at the C-6 position, resulting in high degree of substitution (DS). These cationic polysaccharide derivatives bearing substantial, permanent positive charge dissolve readily in water, and bind strongly with a hydrophilic and anionic surface. Also, we applied this simple and efficient strategy for preparing renewable-based copolymers from commercial cellulose esters. The commercial cellulose ester, cellulose acetate (DS 1.8, CA320S), was employed as an exemplary starting material for preparing polysaccharide-based copolymers by a reaction sequence with very high reaction conversions. These modifications can be carried out with essentially perfect regioselectivity and chemoselectivity, and one advantageous example of this new methodology is the synthesis of novel polyelectrolytes starting from uncharged, commercial, inexpensive cellulose esters. Availability of these cationic polysaccharide derivatives will accelerate structure-property relationship studies, i.e. for biomedical application potential including complexation of poly(nucleic acids) for delivery to cell nuclei, delivery of anionic drugs, and epithelial tight junction opening for oral protein delivery.

Efficient, regioselective path to water-soluble polysaccharide ionomers

253rd National Meeting (2017)

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