Fluorescent Nanoparticles Achieve Efficient Photothermal Conversion and Enhanced Antitumor Efficacy Through Intermolecular Aggregation‐Caused Quenching

ABSTRACT The efficacy of photothermal therapy (PTT) in antitumor applications is often limited by inadequate tumor targeting and low photothermal conversion efficiency (PCE) of photosensitizers. In this study, we designed a photothermal nanoparticle, MPF@IR780, to enhance photosensitizers' targeting and PCE. First, MPF@IR780 improves the delivery of photosensitizers to tumor tissue through the enhanced permeability and retention (EPR) effect. Furthermore, hydrophobic ferrocene was incorporated into the nanoparticle core to increase structural compactness, leading to a strong aggregation‐caused quenching (ACQ) effect and an improved PCE of the photosensitizer under near‐infrared (NIR) irradiation. Mechanistically, MPF@IR780 induces PANoptosis and ferroptosis in cancer cells through thermal damage and oxidative stress, providing an efficient approach for oncotherapy. This strategy of amplifying the effects of PTT by enhancing the ACQ of photosensitizers offers a promising method for advancing the next generation of PTT.