Biomimetic Non‐Conjugated Segment‐Doped Conjugated Polymer Nanoplatform for Bright NIR‐II Imaging‐Guided Phototherapy of Choroidal Melanoma

ABSTRACT Choroidal melanoma, a primary intraocular malignancy, often causes severe vision loss and carries a high risk of metastasis, largely due to the absence of precise and noninvasive theranostic strategies. To address these challenges, we developed a biomimetic NIR‐II theranostic nanoplatform (TPB CNPs) that integrates a nonconjugated polymer (TPB) created by covalently linking NIR‐II fluorescent monomers through flexible C6 alkyl chain spacers to increase brightness. The biomimetic TPB CNPs were camouflaged with the tumor cell membrane to enable efficient uptake and tumor‐specific homing. Upon NIR irradiation, TPB CNPs displayed pronounced NIR‐II fluorescence (quantum yield: 18.3%), primarily type‐I photodynamic reactivity, and an efficient photothermal conversion rate of 77.5%. The bright NIR‐II emission enabled high‐resolution whole‐body angiography and real‐time tumor localization. In vivo studies confirmed that precise imaging‐guided TPB CNPs nearly completely eradicated tumors and significantly prolonged survival in tumor‐bearing mice, with no detectable toxicity. This work introduces a biomimetic NIR‐II nanoplatform that integrates monomers with nonconjugated segments to increase the fluorescence brightness of NIR‐II emissive conjugated polymers, enabling precise, noninvasive imaging‐guided phototherapy of choroidal melanoma.