Air bag-embedded MIL-101(Fe) metal-organic frameworks for an amplified tumor microenvironment activation loop through strategic delivery of iron ions and lentinan.

Iron-based nanocarriers have demonstrated potential in redirecting tumor associated macrophages (TAMs) polarization towards the M1 phenotype, critical for activating the tumor microenvironment (TME) in triple negative breast cancer (TNBC). However, their real-world effectiveness is curtailed by insufficient Fe exposure and the absence of suitable synergists in tumors. We introduce an air bag-embedded iron-based MIL-101 metal-organic frameworks (MOF) for igniting the TME in TNBC through bubble-driven tumoral codelivery of Fe and lentinan. This system, named HM/Ef/LNT-MOF, features nano-sized MOF as the core, embedded NaHCO as a pH-triggered air bag, electrostatically-adsorbed lentinan forming the inner shell, and a shield shell with 4T1&red blood cell hybrid membrane. HM/Ef/LNT-MOF can mitigate non-specific capture in the bloodstream but respond to the acidic tumor milieu, rapidly generating a burst of CO bubbles to disassemble MOF. Upon entering tumors, lentinan-induced interferon-γ (IFN-γ) enable Fe facilitating an enhanced ferroptosis and Fenton-like reaction, pushing TAMs towards M1 polarization via the "IFN-γ-ferroptosis-ROS-Caspase-3" pathway. Moreover, HM/Ef/LNT-MOF increases the infiltration of T lymphocytes and decreases regulatory T cells. These cascading immune responses synergistically foster a loop of amplified TME activation based on TAMs M1 polarization, showcasing notable advancements in anticancer effectiveness and promise for various combination therapies. This study utilizes an "embedded air-bag" strategy to achieve strategic codelivery of Fe and lentinan, providing a new tool for engineering the TME.