Molecularly designed star-shaped PLA-based polymers with enhanced piezoelectricity for ultrasound-driven wound healing.

Poly(lactic acid) (PLA)-based piezoelectric materials are considered promising candidates for smart wound dressings. However, the low crystallinity of PLA limits the ordered arrangement of dipoles, resulting in insufficient piezoelectric output for effective electrical stimulation therapy. In this work, star-shaped poly(ethylene glycol)-poly(L-lactic acid) (sPEG-PLLA) copolymers are synthesized and electrospun into nanofiber membranes. The star-shaped structure can serve as a nucleation site, enabling sPEG-PLLA with a molecular weight of 25k (sPEG-PLLA-25k) to form α-crystals with higher crystallinity. Thus, the sPEG-PLLA-25k nanofiber membrane exhibits the best piezoelectric performance, with a voltage of up to 9 V, which is three times higher than that of the poly(L-lactic acid) (PLLA) membrane (3 V). Both in vitro cell experiments and in vivo wound healing assessments confirm that ultrasound (US)-activated sPEG-PLLA-25k membranes significantly promote cell proliferation and migration, and achieve a higher wound closure rate compared to the PLLA-US group. This work has made breakthroughs in the first attempt to enhance the piezoelectricity of PLA-based materials by a molecular design strategy and developed a dressing with excellent piezoelectric properties and biocompatibility, which provides new materials and strategies for a self-driven electrical stimulation wound healing system.