Implantable ultralow-threshold upconversion lens with self-adaptive photoprotection for intraocular infrared vision

Restricted by the significant non-radiative losses in the anti-Stokes process of converting low-energy photons to high-energy photons of upconversion materials, their applications necessitate high excitation thresholds in infrared imaging, lasers modulation and photodynamic therapy. Herein, we report an implantable upconversion artificial lens capable of converting infrared into visible light with an ultralow excitation power (0.015 mW cm −2 ), and integrating a self-adaptive photoprotection capability to remedy dim light seeing loss and dazzle blindness. Based on the polymeric dynamic coordination bond microenvironment regulation, the non-radiative vibrations could be suppressed to enhance upconversion luminescence via regulating the surface charge of upconversion nanoparticles in polymers by the stretching and contraction of hydrogen bonds. Furthermore, the integrated lens with indium phthalocyanine could activate a graduated photoprotection in 1 ms; this response speed is 1500 times faster than human pupil constriction and dilation. The lens-implanted rabbits achieved retinal responses under ultralow-power infrared illumination and retinal protection from strong light. The fast and clear imaging capabilities greatly shortened the blind time. This research proposes a strategy to achieve low-threshold upconversion and creates an avenue to establish the link between nonlinear optical nanomaterials and biological engineering, and provides a potential approach for bioimaging, phototherapy and wearable devices.