A handy skin wound dressing prepared by alginate and cationic nanofibrillated cellulose derived from solid residues of herbs

Abstract
Large amounts of solid residues are generated after extraction of active ingredients from herbs for the production of natural medicine, but the residues have not been well utilized. In this work, cationic nanofibrillated cellulose (CCNF) was prepared from the solid residues of Astragali Radix by etherification and homogenization. The CCNF was mixed with sodium alginate (SA) to create a hydrogel dressing by physical interactions between CCNF and SA without any addition of cross-linker. The CCNFSA dressing exhibited moderate viscosity, good moisture-maintaining property, great antibacterial activities, good cytocompatibility, and clear acceleration of wound healing on rats. Furthermore, this CCNF-SA dressing with nanofibrous structure had moderate air permeability. Therefore, the CCNF-SA hydrogel could be used potentially as a skin wound dressing. Development of cost-effective and bioactive wound dressing materials is of crucial importance to reduce the burden on patients and healthcare systems. Also, this work provides a new strategy for valorization of the solid residues of herbs.