In-situ and ex-situ EPS-corona formation on ZnO QDs mitigates their environmental toxicity in the freshwater microalgae Chlorella sp.

Summary

EPS coronas formed on ZnO quantum dots, either during (in-situ) or prior to (ex-situ) algal exposure, attenuated oxidative stress, preserved photosynthetic efficiency, and reduced growth inhibition in Chlorella sp., while maintaining ZnO QD fluorescence. These results suggest an eco-corona strategy to mitigate environmental risks of ZnO QDs used in cosmetic products like sunscreens.

Key Findings

• Pristine ZnO QDs induced oxidative stress (elevated ROS, MDA, SOD, catalase) and reduced photosynthetic efficiency with growth inhibition in Chlorella sp.
• Both in-situ and ex-situ EPS coronas (loosely- and tightly-bound) reduced oxidative stress, improved photosynthetic efficiency, and mitigated growth inhibition.
• EPS coronas maintained ZnO QD fluorescence activity, indicating preserved functional properties while reducing toxicity.

Clinical Implications

Encourages formulation scientists and regulators to consider EPS-inspired surface modifications or eco-corona-mimicking approaches for ZnO QDs in sunscreens to mitigate environmental impact while preserving optical performance.

Limitations

• Findings are limited to a microalgal model and may not directly translate to complex ecosystems or human exposure scenarios
• Concentration range (0.25–1.0 mg/L) and single-species testing may not capture real-world variability

Future Directions

Extend testing to multiple trophic levels and field conditions, evaluate long-term eco-corona stability, and explore engineered surface modifications that mimic EPS coronas in formulation contexts.