Toxicity evaluation of boron nitride nanospheres and water-soluble boron nitride in <em>Caenorhabditis elegans</em>

Abstract

Boron nitride (BN) nanomaterials have been increasingly explored for potential biological applications. However, their toxicity remains poorly understood. Using <i>Caenorhabditis elegans</i> as a whole-animal model for toxicity analysis of two representative types of BN nanomaterials - BN nanospheres (BNNSs) and highly water-soluble BN nanomaterial (named BN-800-2) - we found that BNNSs overall toxicity was less than soluble BN-800-2 with irregular shapes. The concentration thresholds for BNNSs and BN-800-2 were 100 µg·mL^-1 and 10 µg·mL^-1, respectively. Above this concentration, both delayed growth, decreased life span, reduced progeny, retarded locomotion behavior, and changed the expression of phenotype-related genes to various extents. BNNSs and BN-800-2 increased oxidative stress levels in <i>C. elegans</i> by promoting reactive oxygen species production. Our results further showed that oxidative stress response and MAPK signaling-related genes, such as <i>GAS1</i>, <i>SOD2</i>, <i>SOD3</i>, <i>MEK1</i>, and <i>PMK1</i>, might be key factors for reactive oxygen species production and toxic responses to BNNSs and BN-800-2 exposure. Together, our results suggest that when concentrations are lower than 10 µg·mL^-1, BNNSs are more biocompatible than BN-800-2 and are potentially biocompatible material.