Ultrafast gelation of multifunctional hydrogel/composite based on self-catalytic Fe3+/Tannic acid-cellulose nanofibers

Multifunctional hydrogels with transparency, ultraviolet (UV)-blocking, stretchable, self-healing, adhesive, antioxidant and antibacterial properties are promising materials for biomedical and relevant applications. However, preparation of these hydrogels at ambient environment without stimuli is still a challenge. Here, a series of hydrogels possessing ultrashort gelation time (similar to 30 s) at room or cold temperature were fabricated based on self-catalytic Fe3+/Tannic acid-cellulose nanofiber (Fe3+/TA-CNF). Fe3+/TA-CNF formed stable redox pairs to activate ammonium persulfate (initiator), generating abundant free radicals to trigger the ultrafast polymerization of acrylic acid (AA). To improve the antibacterial ability of hydrogel, a bilayer hydrogel composite (NF@HG) composed of tetracycline hydrochloride (TH)-loaded electrospun nanofibers and hydrogel layer was fabricated via a mild casting method. The NF@HG exhibited enhanced antibacterial ability and the sustained release of TH can provide long-term antibacterial activity. Besides, cell viability results demonstrated that NF@HG was non-cytotoxic. Taken together, this strategy based on self-catalytic Fe3+/TA-CNF system may inspire new aspects on fast and economical preparation of multifunctional hydrogels or composites, which have attractive industrial applications for biomedical materials. (C) 2021 Elsevier Inc. All rights reserved.