An overlooked effect induced by surface modification: different molecular response of Chlorella pyrenoidosa to graphitized and oxidized nanodiamonds

Abstract

The growing applications of carbon nanomaterials (CNMs) are speculated to exert potential risks to aquatic ecosystems. However, little is known about the response of aquatic microalgae to surface modified nanodiamonds (NDs), which could limit the safer design and scientific assessment for further application. Here, we comprehensively integrated phenotypic and transcriptional analyses to investigate the response of Chlorella pyrenoidosa to both graphitized nanodiamonds (GNDs) and oxidized nanodiamonds (ONDs). Results indicated that 50 mg L⁻¹ GNDs could induce higher growth inhibition with severe organelle damage and oxidative stress than the OND treatment. Intriguingly, extracellular polymeric substances (EPSs) stimulated by OND exposure alleviated the adverse effects. Meanwhile, the conventional global molecular response to surface modified NDs was meticulously disclosed to fill in the knowledge gap. Additionally, the photosynthetic mechanism, amino acid synthesis, protein synthesis and protein export were further investigated under OND treatment, confirming a positive correlation for the crucial strategy to mitigate the negative effect. The underlying mechanism response to GNDs/ONDs has been thoroughly and completely revealed, providing a novel insight for the estimation of ND surface modification and the apperception of aquatic environmental risk.