An Integrated Nanoplatform via Dual Channel Excitation for Both Precise Fluorescence Imaging and Photodynamic Therapy of Orthotopic Breast Tumor in NIR‐II Region

Abstract Although research on photodynamic therapy (PDT) of malignant tumor has made considerable progress in recent years, it is a remaining challenge to extend PDT to the second near‐infrared window (NIR‐II) along with real‐time and accurate NIR‐II fluorescence imaging to determine drug enrichment status and achieve high treatment efficacy. In this work, lanthanide nanoparticles (Ln NPs)‐based nanoplatform (LCR) equipped with photosensitizer Chlorin e6 (Ce6) and targeting molecular NH 2 ‐PEG 1000 ‐cRGDfK are developed, which can achieve NIR‐II photodynamic therapy (PDT) and NIR‐II fluorescence imaging by dual channel excitation. Under 808 nm excitation, Nd 3+ in the outer layer can absorb the energy and transfer inward to emit strong NIR‐II emissions (1064 and 1525 nm). Due to the low background noise of NIR‐II light and the targeting effect of NH 2 ‐PEG 1000 ‐cRGDfK, LCR can recognize tiny tumor tissue (≈3 mm) and monitor drug distribution in vivo. Under 1530 nm excitation, internal Er 3+ can be self‐sensitized, generating intense upconversion emission (662 nm) that can effectively activate Ce6 for in vivo PDT due to the deep tissue penetration of NIR‐II light. This study provides a paradigm of theranostic nanoplatform for both real‐time fluorescence imaging and PDT of orthotopic breast tumor in NIR‐II window.