Black phosphorus nanomaterials mediate size-dependent acute lung injury by promoting macrophage polarization

Black phosphorus nanomaterials (BPNM) exhibit excellent properties and potential applications in electronics, but workers may face inhalation exposure during BPNM production. In addition, there is a lack of biosafety assessments regarding respiratory exposure to BPNM of different sizes. In this study, we investigated the lung toxicity in mice exposed to 5, 50, 500 μg/kg of black phosphorus quantum dots (BPQDs) and black phosphorus nanosheet (BPNS) via single tracheal instillation. The average diameter of the BPQDs and BPNS were 13.48 ± 4.82 nm and 325.53 ± 165.17 nm, respectively. Twenty-four hours after exposure, both BPQDs and BPNS caused acute lung injury, characterized by bronchial wall thickening, alveolar collapse, increased lamellar bodies, and immune cell infiltration. BPNS exposure resulted in reduced gene expression of pulmonary surfactant proteins Spb and Spc. Additionally, both BPQDs and BPNS increased inflammatory factors gene expression and induced lung macrophages polarization, with BPNS demonstrating a more significant effect. This study is the first to show that BPQDs and BPNS induced acute lung injury and inflammation in mice, with BPNS being more toxic. These findings are crucial for enhancing the biosafety assessment of BPNM and advancing technologies to improve the safety of nanomaterials.