Cellulose sulfate/EMIMAc solution: rheological properties and shaping into polyelectrolyte complexes for protein adsorption

Cellulose sulfates (CS) with low degree of substitution (DS) and high degree of polymerization (DP) were prepared via a controlled sulfation modification. The obtained CS with DS 0.42 and DP 293 showed an enhanced solubility of 14.7 g/100 g in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc) compared to unmodified cellulose. The rheological study revealed that the CS/EMIMAc solution behaved as polymers in a theta solvent with the unique three-region flow curves under shear stress. It also showed a property of typical polyelectrolyte solution with the overlap concentration (c*) of 0.2 wt% and the entanglement concentration (c(e)) of 3.0 wt%, respectively. The CS/EMIMAc solution with a concentration of 5 wt% was selected to develop polyelectrolyte complex (PEC) with chitosan using extrusion-spherization and emulsification-solvent evaporation. The produced PEC beads and magnetic microspheres had an average size of 1.0 mm and 22.1 mu m, respectively. The PEC microspheres showed greater absorption capability for bovine serum albumin than the beads with the maximum adsorption value of 780 mg/g.

Automated summary

Cellulose sulfates with low degree of substitution and high degree of polymerization were prepared via controlled sulfation modification, showing enhanced solubility in an ionic liquid and unique flow curves in rheological study. They were further developed into polyelectrolyte complexes with chitosan, demonstrating superior absorption capability for bovine serum albumin.