Abstract

Chronic disease-associated wounds pose significant challenges in suturing, encompassing knot-tying complexity in minimally invasive procedures, instability in edematous wounds, and unsatisfactory wound healing. Herein, we introduce a concept of near-infrared (NIR)-responsive shape-memory polymer (SMP) suture featuring dual functionality: NIR-triggered shape-memory recovery and on-demand drug delivery. The SMP suture is synthesized from poly(L-lactide) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Subsequently, it is modified with copper ion-chelated polydopamine (PDA-Cu 2+ ) complexes and coated with a temperature-sensitive (∼42°C) gelatin hydrogel. Upon exposure to NIR, the PDA-Cu 2+ complexes induce a rapid photothermal effect, which triggers noncontact self-tightening (∼25 s recovery time and near-complete shape recover) of the programmed suture with 80% pre-strain to accelerate wound closure. Meanwhile, the NIR-increased heat governs the "gel-sol" transition of the hydrogel that lowers suture’s T g to 51.46, enhances recovery force to ∼0.4 N and reduces suture friction force to ∼0.35 N, and initiates a "off-on" drug release. Such a NIR-responsive mechanism not only significantly improves fibroblast growth and functionality by enhancing cell-fiber interactions in vitro , but also mitigates inflammatory response and stimulates neovascularization to advance skin regeneration in vivo . Overall, this study develops an NIR-responsive SMP suture with noncontact self-tightening and controlled drug release, enabling on-demand therapeutic interventions for specific wound locations. Statement of Significance For chronic disease-related wounds, high-performance sutures with advanced biofunctionalities have been extensively explored to accelerate healing, as surgical sutures help wound closure while minimizing scar formation. Nevertheless, suturing such wounds remains