Engineering Rigid Nanocarriers to Enhance Photothermal Performance for Suppressing Breast Cancer and Pulmonary Metastasis.

Organic agents with rationally designed structures exhibit enhanced photothermal conversion efficiency (PCE). However, the influence of nanocarriers, commonly employed to improve aqueous dispersibility, has been overlooked. This study investigates the impact of carrier rigidity on the PCE and therapeutic efficacy of organic photothermal nanoparticles (NPs). To examine how carrier rigidity influences NP motion, thermophoresis, and overall photothermal performance, we encapsulated the same organic photothermal agent into different carriers, including polystyrene (PS), phospholipid-based NPs. The results reveal that rigid FT@PS NPs display stronger Brownian motion and higher PCE compared with softer counterparts, implying a potential connection between particle mobility and suppressed nonradiative energy dissipation. Both in vitro and in vivo studies confirmed that FT@PS NPs provided superior therapeutic efficacy, including potent local tumor inhibition, immune activation, and suppress pulmonary metastasis. Collectively, This work establishes carrier rigidity as a critical design parameter for optimizing the photothermal properties and therapeutic efficacy of organic photothermal agents.