Resolution of MoS2 Nanosheets-Induced Pulmonary Inflammation Driven by Nanoscale Intracellular Transformation and Extracellular-Vesicle Shuttles.

Pulmonary exposure to some engineered nanomaterials can cause chronic lesions as a result of unresolved inflammation. Among 2D nanomaterials and graphene, MoS2 has received tremendous attention in optoelectronics and nanomedicine. Here an integrated approach is proposed to follow up the transformation of MoS2 nanosheets at the nanoscale and assesss their impact on lung inflammation status over 1 month after a single inhalation in mice. Analysis of immune cells, alveolar macrophages, extracellular vesicles, and cytokine profiling in bronchoalveolar lavage fluid (BALF) shows that MoS2 nanosheets induced initiation of lung inflammation. However, the inflammation is rapidly resolved despite the persistence of various biotransformed molybdenum-based nanostructures in the alveolar macrophages and the extracellular vesicles for up to 1 month. Using in situ liquid phase transmission electron microscopy experiments, the dynamics of MoS2 nanosheets transformation triggered by reactive oxygen species could be evidenced. Three main transformation mechanisms are observed directly at the nanoscale level: 1) scrolling of the dispersed sheets leading to the formation of nanoscrolls and folded patches, 2) etching releasing soluble MoO4 - , and 3) oxidation generating oxidized sheet fragments. Extracellular vesicles released in BALF are also identified as a potential shuttle of MoS2 nanostructures and their degradation products and more importantly as mediators of inflammation resolution.

Tracking the immune response by MRI using biodegradable and ultrasensitive microprobes.

Molecular magnetic resonance imaging (MRI) holds great promise for diagnosis and therapeutic monitoring in a wide range of diseases. However, the low intrinsic sensitivity of MRI to detect exogenous contrast agents and the lack of biodegradable microprobes have prevented its clinical development. Here, we synthetized a contrast agent for molecular MRI based on a previously unknown mechanism of self-assembly of catechol-coated magnetite nanocrystals into microsized matrix-based particles. The resulting biodegradable microprobes (M3P for microsized matrix-based magnetic particles) carry up to 40,000 times higher amounts of superparamagnetic material than classically used nanoparticles while preserving favorable biocompatibility and excellent water dispersibility. After conjugation to monoclonal antibodies, targeted M3P display high sensitivity and specificity to detect inflammation in vivo in the brain, kidneys, and intestinal mucosa. The high payload of superparamagnetic material, excellent toxicity profile, short circulation half-life, and widespread reactivity of the M3P particles provides a promising platform for clinical translation of immuno-MRI.