A Dual‐Function Hemicyanine Material with Highly Efficient Photothermal and Photodynamic Effect Used for Tumor Therapy

Abstract

Small molecular organic optical agents with synergistic effects of photothermal therapy (PTT) and photodynamic therapy (PDT), holds credible promise for anti‐tumor therapy by overcoming individual drawbacks and enhanced photon utilization efficiency. However, developing effective dual‐function PTT‐PDT photosensitizers (PSs) for efficient synergistic phototherapy remains challenging. Here we present a benz[c,d]indolium‐substituted hemicyanine named Rh‐BI, which possesses a high photothermal conversion efficiency of 41.67% by exhaustively suppressing fluorescence emission. Meanwhile, the rotating phenyl group at meso‐site induced charge recombination to enhance the molar extinction coefficient up to 13.58×10⁴ M⁻¹cm⁻¹, thereby potentiating the photodynamic effect. Under 808 nm irradiation, Rh‐BI exhibited significant phototoxicity in several cancer cell types in vitro with IC₅₀ values as low as about 0.5 μM. Moreover, treatment of 4T1 tumor‐bearing mice with Rh‐BI under laser irradiation successfully inhibits tumor growth. In a word, we developed an effective strategy to build PTT‐PDT dual‐functional optical materials based on hemicyanine backbone for tumor therapy by modulating conjugation system interaction to adjust the energy consumption pathway.

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