Specific and Long‐Term Luminescent Monitoring of Hydrogen Peroxide in Tumor Metastasis

Abstract Luminescent monitoring of endogenous hydrogen peroxide (H₂O₂) in tumors is conducive to understanding metastasis and developing novel therapeutics. The clinical transformation is obstructed by the limited light penetration depth, toxicity of nano‐probes, and lack of long‐term monitoring modes of up to days or months. New monitoring modes are introduced via specific probes and implantable devices, which can achieve real‐time monitoring with a readout frequency of 0.01 s or long‐term monitoring for months to years. Near‐infrared dye‐sensitized upconversion nanoparticles (UCNPs) are fabricated as the luminescent probes, and the specificity to reactive oxygen species is subtly regulated by the self‐assembled monolayers on the surfaces of UCNPs. Combined with the passive implanted system, a 20‐day monitoring of H₂O₂ in the rat model of ovarian cancer with peritoneal metastasis is achieved, in which the limited light penetration depth and toxicity of nano‐probes are circumvented. The developed monitoring modes show great potential in accelerating the clinical transformation of nano‐probes and biochemical detection methods.