Sono‐Controllable Janus Microneedle for Postsurgical Tumor Eradication and Scarless Wound Healing in Melanoma

Post‐surgical melanoma patients often face poor wound healing and high recurrence rates due to extensive tissue defects and incomplete tumor removal. Herein, a sono‐activated multifunctional Janus microneedle (MN) is developed composed of chlorella (Chl) and modified 2D layered double hydroxide amorphous CoW‐LDH (LDH). This innovative design activates LDH and allows the transplanted microorganisms to continuously produce dissolved oxygen. This mechanism effectively eliminates residual tumor tissue and promotes scarless skin tissue repair. LDH functions as a reactive oxygen species (ROS) emitter, efficiently producing a large quantity of ROS with ultrasound (US) control to target and kill residual tumor cells and improve antibacterial activity. Concurrently, transdermal microneedle‐encapsulated Chl is transplanted in situ at the trauma site to ensure oxygen supplication. This approach not only inhibits mitophagy to enhance the tumor‐killing effect, but also increases ROS generation, thereby eradicating remaining subcutaneous tumor cells and preventing melanoma recurrence, maintaining oxygen supplication. Moreover, it upregulates the expression of angiogenesis‐related genes, facilitating traceless skin tissue repair. The multifunctional Chl/LDH‐MN shows vital biological functions and remarkable biocompatibility. When used with clinically achievable US irradiation, it effectively addresses dual demands of eradicating tumors and promoting wound healing, demonstrating significant potential in both wound healing and cosmetic repair.