Scheme 1

Implantable micro-scale LED device (micro-LED) guided photodynamic therapy (PDT) to potentiate antitumor immunity with mild visible light. (a) The micro-LED is prepared by stacking micro-scale LEDs fabricated on a polyimide (PI) substrate and transferred onto an injection guide, which was designed as a needle-like structure with polysiloxane acrylate. (b) The micro-LED is directly implanted into the core part of the tumor tissues, followed by irradiation with visible light. (c) The mechanism of micro-LED guided PDT in the tumor tissues depending on the optimal, less or over light intensity. Under the optimal light intensity, the tumor cells release DAMPs through PDT-mediated ICD, thereby promoting DC maturation and with T cell activation to inhibit the progression of primary and recurrence tumors by antitumor immunity. When over light intensity is irradiated to tumor tissues, severe inflammatory responses are induced by necrotic cell death, which releases the immunosuppressive cytokine IL-10 and activates regulatory T cells, resulting in immunosuppression. In the case of tumor tissues irradiated with too low light intensity, a potent antitumor immunity is not induced owing to the insufficient ICD in tumor cells