An Extensively Adhesive Patch with Multiple Physical Interactions and Chemical Crosslinking as a Wound Dressing and Strain Sensor

Non-covalent or dynamic covalent materials have been widely explored and utilized to construct bioadhesives. Due to the presence of dynamic disulfide bonds and other non-covalent interactions, α-lipoic acid (ALA) supramolecular copolymers with adjustable mechanical, self-healing, and adhesive properties were achieved recently. However, their applications in biomedicine are limited by their weak adhesion to tissues and the potential toxicity of organic solvents and small molecule monomers that are inevitably introduced in polymerization to endcap and stabilize PALA. In this study, a PALA-PDA-HPAE-Ag elastomer is reported to surmount the above disadvantages and exhibit a wide potential application. The addition of polydopamine nanoparticles (PDA NPs) to PALA is easily achieved in an aqueous phase preparation and thus improves the adhesive strength to tissues. The acrylate-terminated hyperbranched poly β-amino ester (HPAE) is used to endcap and stabilize PALA, thus avoiding the toxicity of small molecules; meanwhile, the imidazole in HPAE can strongly chelate various metal ions. A typical in situ ALA-Ag+ reduction produces Ag NPs that can strongly complex PALA to improve the mechanical strength and endow the material with excellent antibacterial properties. The prepared patch has promising self-healing ability without external stimulation and excellent mechanical properties and demonstrates extensive adhesion to a variety of materials including animal tissues. The good biocompatibility and wound healing effect on a full-thickness skin defect model are also verified. Additionally, the PALA-PDA-HPAE-Ag elastomer can be utilized as an adhesive strain sensor to accurately monitor and record joint bending and extension by measuring the changes of resistance signals during deformation, which suggests a great application potential in rapid and accurate detection of external changes and human movements. In conclusion, we have obtained a PALA-PDA-HPAE-Ag elastomer material that can meet the diversified needs of medical treatment through deliberate structural design.