NIR-Programmable Stealth 2D Black Phosphorus Nanobiointerfaces for Deep Tumor Penetration and Photoimmunotherapy

Black phosphorus (BP) nanosheets are attractive candidates for nanomedicine applications, but their unfavorable protein corona and poor tumor penetration limit their clinical translation. Here, we report PTPBP, a light-activatable nanoplatform with a BP core and a reactive oxygen species (ROS)-responsive polyethylenimine-thioketal-polyethylene glycol (PEI_1.8k-TK-PEG_5k) coating, engineered to sequentially overcome these biological barriers through near-infrared (NIR)-programmable nanobiointerfaces. Our surface stealth strategy proactively manages the protein corona, enriching complement inhibitory proteins while depleting opsonins, thereby attenuating immunogenicity and increasing tumor-specific accumulation by 3.4-fold. Upon NIR irradiation at the tumor site, BP-generated ROS cleave the thioketal (TK) linker, detaching the PEG shield and exposing the underlying cationic PEI. This spatiotemporal charge conversion facilitates programmable interactions with biointerfaces, promoting transvascular extravasation, deep tumor penetration, cellular uptake, and lysosomal escape. By coloading Mn²⁺ and Indoximod, PTPBP@Mn²⁺/Indoximod enables synergistic photoimmunotherapy by inducing immunogenic cell death (ICD), activating the cGAS-STING pathway, and inhibiting the indoleamine 2,3-dioxygenase (IDO) pathway. In orthotopic breast cancer models, this strategy potently inhibits primary and metastatic tumors and establishes long-term immunological memory. By integrating "stealth-by-design" corona management and precise spatiotemporally activated charge conversion, this work facilitates the rational development of high-efficiency nanotherapeutics for cancer and broader disease applications.