A Janus nanofibrous scaffold integrated with exercise-driven electrical stimulation and nanotopological effect enabling the promotion of tendon-to-bone healing

Rotator cuff tear and repair presents a significant challenge on a global scale due to the ineffectiveness of current treatments involving single sutures or synthetic scaffolds in achieving genuine healing of complex and heterogeneous tendon and bone. Wireless bioelectrical therapy is emerging as a promising approach to overcome the existing limitations. Herein, a Janus nanofibrous scaffold with piezoelectric performance and biomimetic collagen fiber arrangement structure was conceptualized and constructed to promote simultaneous tendon-to-bone healing. Specifically, the scaffold was prepared by electrospinning back-to-back layers of poly (L-lactic acid)/zinc oxide (PLLA/ZnO) and PLLA/barium titanate (PLLA/BTO), with the fiber alignments adjusted from orientation to random by manipulating the rotating speed of the roller. The bionic alignment of the fibers endowed the scaffold with remarkable tensile and suture retention strength, thereby meeting the mechanical demands for tendon-to-bone healing. Meanwhile, the scaffold offered topographical guidance for cellular interaction. The integration of ZnO and BTO nanoparticles within the PLLA matrix resulted in excellent piezoelectric response, as well as induced tenogenic and osteogenic differentiation, respectively. Moreover, the slow degradation of PLLA and the exceptional piezoelectric property guaranteed the scaffold stable exercise-driven local electrical stimulation to promote tendon and bone healing, which could be evidenced by the enhanced repair effect observed in a rat rotator cuff tear model. This study effectively showcases the potential of integrating a Janus piezoelectric scaffold with suitable exercise training to boost tissue healing, offering a unique therapeutic material and strategy for sports medicine.