A paintable composite hydrogel patch for potential wound dressings

[Display omitted] •A paintable composite hydrogel patch for potential chronic wound repair.•An easy-to-operate paintable hydrogel was achieved by controlling APS initiation.•The hydrogel exhibits a superior adhesion strength to commercial fibrin glue.•Gel design employs DN strategy, multiple hydrogen bonds and ionic coordination.•The hydrogel patch has satisfactory mechanical strength and cytocompatibility. Hydrogel has incomparable advantages in promoting chronic wound healing due to its high-water content, softness and excellent physiological activity. However, as a treatment platform, most hydrogel dressings are fixed at the wound site in block form, which is difficult to fully contact and fit with the tissue, limiting their efficacy. Here, a composite hydrogel that can be conveniently painted to material surface and closely adhered is developed. The hydrogel is obtained through a double network strategy and multiple non-covalent interactions between N-(3,4-dihydroxyphenylethyl) acrylamide (NA)-acrylic acid-acrylamide terpolymer, nano Fe3O4 and chitosan. NA monomer with catechol-like structure can significantly improve the adhesion strength of the hydrogel to 25.06 kPa, which is superior to the commercially available fibrin glue (∼11.5 kPa). Notably, the high-efficiency paintability of the hydrogel can be achieved just by the initiation of ultra-trace potassium persulfate. The hydrogel patch also exhibits satisfactory mechanical properties and cytocompatibility. Hence, this multifunctional hydrogel will be conveniently painted to the wound bed as a patch without adverse liquid leakage, providing an optimistic material for chronic wound treatment.