Biohybrid Chlorella-HSA with Self-Oxygenation and Dual-Modal activation for synergistic Photo-Sonodynamic immunotherapy

Multimodal dynamic therapies enhance precision oncology by synergistically harnessing reactive oxygen species (ROS)-mediated cytotoxicity, as exemplified in photodynamic and sonodynamic modalities. However, it faces key challenges including hypoxic tumors, low ROS yields, poor deep-tissue penetration, and immunosuppressive niches. To address these challenges, we engineered Chlorella vulgaris (Chl) into a biohybrid platform through sequential integration with 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphine tetraiodide (TPP) and human serum albumin (HSA) (termed Chl@TPP/HSA) for synergistic photo-sonodynamic immunotherapy. This system integrates the photosynthetic oxygenation capacity of Chl with the dual photo-sonosensitizing properties of TPP, thereby overcoming hypoxia and amplifying cytotoxic effects. Due to surface functionalization with HSA, tumor-targeted accumulation was improved by 6.4-fold compared with that of unmodified Chl. In vitro and in vivo studies demonstrated that Chl@TPP/HSA under laser and ultrasound (US) irradiation effectively induced immunogenic cell death (ICD), which was marked by high mobility group box 1 (HMGB1) translocation, ATP release, and calreticulin (CRT) exposure. These effects synergistically activated dendritic cell (DC) maturation (42.5 % CD80 + CD86 + increase), enhanced natural killer (NK) cell cytotoxicity (59.5 % upregulation of CD107a + ), promoted cytotoxic CD8 + T-cell infiltration (32.5 % increase), and polarized macrophages toward the M1 phenotype (30.7 % reduction in CD206 + cells). Systemic administration of Chl@TPP/HSA achieved a 91.7 % reduction in tumor volume in the 4 T1 breast cancer model via synergistic photo-sonodynamic immunotherapy. These results establish Chl@TPP/HSA as a multifunctional platform that integrates self-oxygenation, dual-modal ROS generation, and immunomodulation, offering an effective strategy for precision oncology.