Rational Design of All‐Organic Nanoplatform for Highly Efficient MR/NIR‐II Imaging‐Guided Cancer Phototheranostics

Abstract Organic theranostic nanomedicine has precision multimodel imaging capability and concurrent therapeutics under noninvasive imaging guidance. However, the rational design of desirable multifunctional organic theranostics for cancer remains challenging. Rational engineering of organic semiconducting nanomaterials has revealed great potential for cancer theranostics largely owing to their intrinsic diversified biophotonics, easy fabrication of multimodel imaging platform, and desirable biocompatibility. Herein, a novel all‐organic nanotheranostic platform (TPATQ‐PNP NPs) is developed by exploiting the self‐assembly of a semiconducting small molecule (TPATQ) and a new synthetic high‐density nitroxide radical‐based amphiphilic polymer (PNP). The nitroxide radicals act as metal‐free magnetic resonance imaging agent through shortened longitudinal relaxation times, and the semiconducting molecules enable ultralow background second near‐infrared (NIR‐II, 1000–1700 nm) fluorescence imaging. The as‐prepared TPATQ‐PNP NPs can light up whole blood vessels of mice and show precision tumor‐locating ability with synergistic (MR/NIR‐II) imaging modalities. The semiconducting molecules also undergo highly effective photothermal conversion in the NIR region for cancer photothermal therapy guided by complementary tumor diagnosis. The designed multifunctional organic semiconducting self‐assembly provides new insights into the development of a new platform for cancer theranostics.