Anti-Microbial Biopolymer Hydrogel Scaffolds for Stem Cell Encapsulation

Biopolymer hydrogels are an attractive class of materials for wound dressings and other biomedical applications because of their ease of use and availability from biomass. Here, we present a hydrogel formation approach based on alginate and chitosan. Alginate is conventionally cross-linked using multivalent ions such as Ca2+ but in principle any polycationic species can be used such as polyelectrolytes. Exchanging the cross-linking Ca2+ ions partially with chitosan, which at pH 7 has available positive charges as well as good interactions with Ca2+, leads to an improved Young's modulus. This gel is non-toxic to mammalian cells and hence allows conveniently for stem cell encapsulation since it is based on two-component mixing and gel formation. Additionally, the chitosan is known to have a bactericidal effect which is retained when using it in the alginate-chitosan gel formation and the formed hydrogels displayed bactericidal effects against P. aeruginosa and S. aureus. The combination of anti-bacterial properties, inclusion of stem cells, and the hydrogel nature would provide an ideal environment for complex wound healing.