Small Black Phosphorus Disrupts Vascular Development and Hematopoiesis in Zebrafish Larvae

Black phosphorus (BP), a novel two-dimensional (2D) material, has shown promising applications in the optoelectronic, biological, and medical fields in recent years. However, its increasing use may lead to its inadvertent environmental release, creating potential ecological and health risks that remain poorly understood. In this study, wild-type and transgenic zebrafish were used to evaluate the potential developmental toxicity of small-size BP (S-BP), with a lateral particle size of 154.4 ± 34.6 nm, focusing specifically on vascular growth and hematopoiesis at relatively low concentrations of 0.025, 0.05, 0.1, and 0.2 mg/L. The results indicated that S-BP adhered to the chorion and induced developmental defects. The uninflated swim bladders and decreased heart rate were observed in S-BP-exposed larvae at 120 hpf. The angioarchitectural profiling using transgenic zebrafish showed that exposure to S-BP adversely impaired blood vessel development at 72 hpf, especially in the common cardinal vein (CCV). Moreover, erythropoiesis and the flow velocity of red blood cells (RBCs) were disturbed at 120 hpf in all of the S-BP-exposed groups. Transcriptomic analysis unveiled that S-BP exposure altered gene expression related to angiogenesis, hematopoiesis, ribosome function, and transport processes. Notably, the mRNA levels of vascular and hematopoietic markers, including <i>clec14a</i>, <i>nme2b.1</i>, <i>klf2a</i>, <i>slc2a1a</i>, <i>csf1rb</i>, <i>atf3</i>, <i>scl</i>, and <i>scml4</i>, were significantly downregulated following S-BP exposure. Our findings revealed that low concentrations of S-BP exposure caused vascular and hematologic toxicity and identified CCV and RBCs as sensitive targets. This work expands our understanding of the toxicity of 2D nanomaterials and provides critical data for environmental risk assessment.