Multifunctional, NIR light-responsive, 4D printable polyurethane/polydopamine nanocomposite

Multifunctional biomaterials are vigorous development in recent period. Implanting biomaterials with minimal invasion and antibacterial activity are relentless demand. Herein, copper ion-loaded polydopamine nanoparticles (Cu(II)@PDA NPs) were incorporated into shape memory polyurethane (SMPU) to obtained 4D printable nanocomposites with excellent near-infrared (NIR) light responsiveness and antibacterial properties, which are crucial for tissue engineering applications. Firstly, a series of well-dispersed Cu(II)@PDA/PU nanocomposites were successfully prepared, and their structure and properties were systematically investigated. The nanocomposites showed robust mechanical properties and good biocompatibility. Then, under 808 nm NIR laser irradiation, the nanocomposites exhibited significant photothermal effects. Typically, it reached temperature of 53.5 °C for Cu(II)@PDA 0.5 /PU in 10 min under NIR. So that, it achieved 92.7 % antibacterial efficiency to avoid implant infection. Finally, the 4D printing capability of the shape memory nanocomposite was demonstrated, which showed rapid shape recovery within 16 s. Due to their multifunctionality, the nanocomposites hold great potential for use in minimally invasive implant biomaterials.