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. Author manuscript; available in PMC: 2020 Jan 28.
Published in final edited form as: J Control Release. 2018 Nov 27;294:53–76. doi: 10.1016/j.jconrel.2018.11.024

Figure 11.

Figure 11.

CNF-based hydrogel beads for the controlled release of probiotics. (a) Cellulose fibrils undergo TEMPO-mediated oxidation, resulting in the carboxylate conjugation to the C6 of monomers (glucose). (b) The oxidized nanofibrils are mixed with cellulose fibers in an aqueous solution containing LiOH/urea/water and maintained at −20°C, followed by freeze-thawing and centrifugation. The product is added to a dilute hydrochloric acid solution to form the beads with various CNF-to-cellulose fiber ratios. (c) The bead pore size may be regulated by changing the concentration of CNF; the higher the CNF, the larger the pores. (d) The engineered porosity of gel beads and their pH-responsiveness originated from the carboxylic acid groups enable the controlled release of probiotics [190]. Reprinted with permission from [190]. Copyright (2018) American Chemical Society.