Biomineralized Bacterial Biohybrid for Coordinated and Self-Sustained In Situ Synthesis of Antitumor Photothermal Agent and Photosensitizer.

Abstract

Synergizing photodynamic therapy (PDT) and photothermal therapy (PTT) in a single platform is a promising strategy against cancer, but its efficacy requires simultaneous delivery of sufficient amounts of both therapeutic agents for PDT and PTT. Here, we develop a CuS-mineralized bacterial biohybrid, EcN-HT@CuS, that synthesizes photosensitizer (protoporphyrin IX) and photothermal agent (melanin) continuously in situ within tumors, relying on no external substrate supply. The biohybrid, engineered with inducible genetic circuits encoding 5-aminolevulinate synthase for synthesis of protoporphyrin IX precursor and tyrosinase for melanin production, is surface-mineralized with CuS nanoparticles to supply the Cu²⁺ cofactor for apo-tyrosinase. EcN-HT@CuS selectively colonizes and proliferates within tumors and is programmed to produce protoporphyrin IX and melanin on-demand, allowing sequenced PDT and PTT mediated by red light and near-infrared light, respectively. The combination therapy induced immunogenic tumor cell death, evidenced by robust infiltration of CD8⁺ T cells and a shift toward a proinflammatory tumor microenvironment. This work establishes a programmable antitumor biohybrid system that integrates targeted drug delivery, controlled phototherapy, and immune activation.