(541d) Improving Self-Assembly, Uniformity, and Mechanics of Cellulose Gel Beads with Salt

Cellulose is used to fabricate a diverse array of material platforms for oral drug delivery due to being sustainable, biocompatible, and having great mechanical and transport properties. Cellulose microgel beads are often fabricated by dropping cellulose/sodium hydroxide/urea solutions into a hydrochloric acid (HCl) coagulation bath. However, beads fabricated using the dropping technique suffer from lack of structural uniformity, variable and subpar mechanical properties, and uncontrolled pore structure. To address these challenges, we use thermal and salt-driven methods to control the self-assembly mechanism of cellulose in solution prior to dropping. We can fabricate beads that are structurally uniform throughout their 3-D geometry and that retain their mechanical properties when exposed to a simulated gastrointestinal tract (SIT) environment. While thermal gelation can improve the uniformity of the cellulose network in the bead, the beads still displayed areas with voids and cracks. However, adding critical concentrations of salt to the cellulose solution results in geometrically uniform beads with a uniform, porous internal structure. Ultimately, utilizing solution-based self-assembly toolkits can help tune the hierarchical self-assembly and overcome the salt-driven aggregation and migration of cellulose caused by the neutralization reaction during coagulation. Hence, this work shows the feasibility of increasing uniformity and performance of native cellulose materials. By reducing batch to batch variability in terms of bead size, circularity, porosity, and mechanical properties, we are able to translate native cellulose into sustainable material platforms – particularly for biomedical applications – without the need for chemical modification.