Sustainable Polylactic Acid-Derived Polyurethane/MXene Microneedles for Stimulus-Responsive Transdermal Delivery

The convergence of sustainability and advanced functionality is critical in the design of next-generation biomedical materials. Here, we report a biodegradable microneedle (MN) platform composed of polyurethane (PU) synthesized by the chemical recycling of polylactic acid (PLA). This green strategy upcycles PLA waste to produce a flexible, mechanically robust matrix suitable for transdermal applications. Incorporation of a trace amount (∼0.005 wt %) of delaminated Ti₃C₂T _x MXene imparts photothermal responsiveness under near-infrared (NIR) irradiation, antioxidant capacity (demonstrated using in vitro radical-scavenging assays), and improved mechanical strength. These features enable heat-triggered model drug release and suggest the potential for managing local oxidative stress in wound environments. In vitro assessments confirmed effective skin penetration, photothermal cycling stability, and acceptable cytocompatibility. This proof-of-concept study establishes a sustainable, multifunctional MN platform that integrates circular polymer design with stimuli-responsive performance, supporting future development for advanced transdermal drug delivery applications.