Physiological and metabolic responses of Euglena gracilis to pristine and copper-doped carbon dots

MA Ping-jia; CAI Kang-li; WANG Xin-wei; LI Mei

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China Environmental Science ›› 2025, Vol. 45 ›› Issue (5) : 2913-2925.

Environmental Toxicology and Environmental Health

Physiological and metabolic responses of Euglena gracilis to pristine and copper-doped carbon dots

MA Ping-jia, CAI Kang-li, WANG Xin-wei, LI Mei

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Abstract

To elucidate the potential ecological risks of carbon dots, a novel nanomaterial, this study investigated the physiological responses and underlying mechanisms of the freshwater microalgae Euglena gracilis following exposure to pristine carbon dots (CDs) and Cu-N-doped carbon dots (Cu-CDs). The results demonstrated that both types of carbon dots initially promoted but subsequently inhibited the growth of E.gracilis over time. Compared to CDs, Cu-CDs exerted a more pronounced impact on key physiological processes, including photosynthesis and antioxidant defense. Exposure to 1mg/L and 10mg/L Cu-CDs resulted in the accumulation of photosynthetic pigments and a decline in photosystem II activity, whereas a significant change in photosynthetic pigment content was observed only at 10mg/L in the CDs-exposed group. The maximum inhibition rates of superoxide dismutase activity induced by CDs and Cu-CDs were 62.52% and 78.35%, respectively. Metabolomics analysis further confirmed that Cu-CDs triggered a stronger metabolic disturbances, with the most notable alterations observed in lipid metabolism pathways, indicating compromised membrane stability of E.gracilis. Disruptions in amino acid and photosynthetic metabolism pathways were primarily attributed to oxidative stress. Additionally, both CDs and Cu-CDs affected energy metabolism by altering in alanine, aspartate, and glutamate metabolism, as well as glycolysis/gluconeogenesis pathways. Overall, the impairment of photosynthetic and antioxidant system may represent the primary toxic mechanisms of carbon dots in E.gracilis.

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Euglena gracilis / carbon dots / physiological response / toxic mechanism

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MA Ping-jia, CAI Kang-li, WANG Xin-wei, LI Mei. Physiological and metabolic responses of Euglena gracilis to pristine and copper-doped carbon dots[J]. China Environmental Science. 2025, 45(5): 2913-2925

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