Tunable Bio-Derived Skin-Like Shape Memory Fibers for Smart Suturing

Materials made from bile acids can benefit from the excellent biocompatibility and rigid skeleton of these natural compounds. To address concerns of the biocompatibility of shape-memory polymers (SMPs) in biomedical applications, a series of polyurethanes (PUs) is developed using bile acid as the hard segment and oligo(ethylene glycol) as the soft segment through a one-pot polymerization. These polymers can be easily processed into skin-like fibers, tubes, strips, etc., with tunable mechanical properties, e.g., elongation at break (483%) and high tensile strength (40.9 MPa). Their glass transition temperatures spread across a wide range, enabling them to exhibit dual, triple, and quadruple shape memory effects (SMEs). Due to intermolecular interactions, these PUs display a maximum self-healing efficiency of 96% in tensile strength for 1.5 h. In vitro cytotoxicity tests, hemolysis evaluations and healing efficiency in vivo all indicate their good biocompatibility and biosafety. These bio-derived PUs offer an option of shape memory polymers easy to make, with good tissue compatibility for applications as surgical sutures, artificial muscles, and soft materials.