, Volume 21, Issue 3, pp 1529-1540
Date: 07 Feb 2014

Characterization of anionic and cationic functionalized bacterial cellulose nanofibres for controlled release applications

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Abstract

Bacterial cellulose (BC) is a biocompatible biopolymer synthesized by Gluconacetobacter xylinus. In this study, BC was oxidized and aminated to produce hydrogels for biomedical applications, and the products were characterized. A carboxyl (pKa of 3.9 ± 0.1) content of 1.13 ± 0.02 mmol/g was obtained with the TEMPO-catalyzed oxidation. Epichlorohydrin-mediated amination introduced amine groups (pKa of 11.0 ± 0.1) up to 1.74 ± 0.06 mmol/g. The oxidation of BC caused a decrease in its ζ-potential to −103 ± 6 mV, and amination increased the ζ-potential to −4 ± 6 mV. The fibre diameter decreased after both reactions. The high absolute value of the ζ-potential for oxidized BC led to superior colloidal stability in water, and a 390 % increase in water retention. The oxidized BC hydrogel was also found to increase in water retention fivefold from pH 1 to 7, making it a smart hydrogel. The cationic and anionic BC hydrogels described here could be used for several biomedical applications, including self-assembling drug delivery devices.