Dual ionic crosslinked interpenetrating network of alginate-cellulose beads with enhanced mechanical properties for biocompatible encapsulation

Spherical hydrogels (???micro beads???) made from alginate has been explored and used for biomedical application, delivery of biomolecule and cell transplantation, although restricted mechanical strength and short-term structural cohesion. In this study, controlling mechanical properties and maintaining the long-term structural integrity of spherical hydrogels could be achieved by creating interpenetrating networks (IPN) of alginate and aqueous-soluble cellulose with divalent and trivalent ions. By using various the aqueous-soluble cellulose, with varying concentration of cellulose or types of ions, the moduli of the resulting hydrogels could be controlled in a wide range with a simple yet highly efficient method of engineering alginate beads. The aqueous-soluble cellulose is found to undergo crosslinking reaction with trivalent ions more favorably than divalent ions, processing a dual sequential ionic crosslinking scheme to create IPN of alginate and cellulose with divalent and trivalent ions, respectively. Especially, the aqueous-soluble anionic cellulose, containing either carboxylate or sulfonate, is easier to control mechanical properties than other types of celluloses. Furthermore, the IPN alginate-cellulose beads demonstrate enhanced resistance to harsh chemical environment as compared to alginate beads and suitability for biomedical applications by encapsulating microbial species and therapeutic agents for controlled release