Environmental Hazard Potential of Nano‐Photocatalysts Determined by Nano‐Bio Interactions and Exposure Conditions

Abstract

Nano‐photocatalysts are known for their ability to degrade pollutants or perform water splitting catalyzed by light. Being the key functional ingredients of current and future products, the potential of nano‐photocatalysts releasing into the environment and causing unintended harm to living organisms warrants investigation. Risk assessment of these materials serves as an important step to allow safe implementation and to avoid irrational fear. Using TiO2 and g‐C3N4 as representative nano‐photocatalysts, this study evaluates their hazard potential in zebrafish. Under simulated solar light, nano‐photocatalysts up to 100 mg L−1 show no acute toxicity to zebrafish embryos due to the protection of chorions. The short‐lived reactive oxygen species generated by nano‐photocatalysts only exert injury to the hatched larvae at and above 50 mg L−1. The input of solar energy, determined by the depth of water, irradiation time, and light intensity, greatly influences the toxicity outcome. Increasing concentrations of natural organic matters contribute positively to the hazard potential at 0–10 mg L−1 while gradually diminishing the hazardous effect above 10 mg L−1. This study demonstrates the importance of nano‐bio interactions and environmental exposure conditions in determining the safety profile of nano‐photocatalysts.

Enhanced visible light-driven photodegradation of tetracycline by salicylic acid-modified graphitic carbon nitride and toxicity assessment

“…The acute toxicity of catalysts, TC solution, and treated TC solutions were assessed using zebra sh embryos (He et al 2020). In each well of 96-well plates, one zebra sh embryo and 200 µL of suspension were added.…”

“…But, to the best of our knowledge, there are no reports to evaluate the possible toxicity of the transformation products during the degradation process (benzene-ring-modi ed g-C 3 N 4 system). Meanwhile, the increasing applications of g-C 3 N 4 photocatalysts have also triggered safety concerns (He et al 2020. Their potential risks are seldomly reported.…”

Mitigation Effects and Associated Mechanisms of Environmentally Relevant Thiols on the Phytotoxicity of Molybdenum Disulfide Nanosheets

“…The generation of reactive intermediates and the dysfunction of antioxidant enzymes in cells are the predominant mechanisms for reactive oxide species (ROS)-dependent and -independent oxidative stress triggered by ENMs, respectively, , which are toxic to organisms. Covalent functionalization not only alters the damaging effects of MoS 2 nanosheets on biomolecules by passivating active sites but also likely affects n-type semiconductive characteristics and energy band structures, , which determine the capability of MoS 2 to generate reactive intermediates.…”

“…Nevertheless, unlike other substances widespread in the aquatic environment (e.g., humic acids, natural colloids, and proteins), 18−20 the impacts of ERTs on the environmental fate and toxicity of MoS 2 have been rarely examined and thus warrant further exploration. The generation of reactive intermediates and the dysfunction of antioxidant enzymes in cells are the predominant mechanisms for reactive oxide species (ROS)-dependent and -independent oxidative stress triggered by ENMs, respectively, 21,22 which are toxic to organisms. Covalent functionalization not only alters the damaging effects of MoS 2 nanosheets on biomolecules by passivating active sites 22 but also likely affects n-type semiconductive characteristics and energy band structures, 19,23 which determine the capability of MoS 2 to generate reactive intermediates.…”

Multigenerational Exposure to Nano‐TiO2 Induces Ageing as a Stress Response Mitigated by Environmental Interactions

“…The environmental hazard potential of TiO 2 NMs has been previously investigated in different aquatic organisms, including algae, [ 6,7 ] Daphnia , [ 8,9 ] and zebrafish. [ 10–12 ] The common responses to TiO 2 NM exposure included inhibited growth, [ 13 ] oxidative stress, [ 6,10,12 ] and bioaccumulation. [ 8,14 ] However, these investigations only used pristine TiO 2 NMs and did not make comparisons with their aged NM counterparts, nor did they explore multigenerational effects.…”