Injectable muscle-adhesive antioxidant conductive photothermal bioactive nanomatrix for efficiently promoting full-thickness skeletal muscle regeneration

The completed skeletal muscle regeneration resulted from severe injury and muscle-related disease is still a challenge. Here, we developed an injectable muscle-adhesive antioxidant conductive bioactive photothermo-responsive nanomatrix for regulating the myogenic differentiation and promoting the skeletal muscle regeneration in vivo. The multifunctional nanomatrix was composed of polypyrrole@polydopamine (PPy@PDA, 342 +/- 5.6 nm) nanoparticles-crosslinked Pluronic F-127 (F127)-polycitrate matrix (FPCP). The FPCP nanomatrix demonstrated inherent multifunctional properties including excellent photothermo-responsive and shear-thinning behavior, muscle-adhesive feature, injectable ability, electronic conductivity (0.48 +/- 0.03 S/m) and antioxidant activity and photothermal function. The FPCP nanomatrix displayed better photothermal performance with near-infrared irradiation, which could provide the photo-controlled release of protein (91% +/- 2.6% of BSA was released after irradiated 3 times). Additionally, FPCP nanomatrix could significantly enhance the cell proliferation and myogenic differentiation of mouse myoblast cells (C2C12) by promoting the expressions of myogenic genes (MyoD and MyoG) and myosin heavy chain (MHC) protein with negligible cytotoxicity. Based on the multifunctional properties, FPCP nanomatrix efficiently promoted the full-thickness skeletal muscle repair and regeneration in vivo, through stimulating the angiogenesis and myotube formation. This study firstly indicated the vital role of multifunctional PPy@PDA nanoparticles in regulating myogenic differentiation and skeletal muscle regeneration. This work also suggests that rational design of bioactive matrix with multifunctional feature would greatly enhance the development of regenerative medicine.