Species-specific ecotoxicity of platinum nanoparticles to two cyanobacteria.

Platinum nanoparticles (PtNPs) are one of the widely used NPs, which contribute to potential risks to the aquatic ecosystem. However, PtNPs toxicity in phytoplankton remains inadequately understood, with significant gaps in knowledge regarding their biochemical bases and species-specific responses. Herein, we investigated the impact of PtNPs on two cyanobacterial species (Anabaena laxa and Nostoc muscorum) to explore the harmful pathways triggered by PtNPs in cyanobacteria, which may help in selecting appropriate biomarkers for PtNPs pollution in aquatic environments. We studied the effect of PtNPs on growth, oxidative stress markers, and antioxidant defense systems of the two species. The obtained results showed that PtNPs reduced the level of chlorophyll. Furthermore, they induced dose-dependent oxidative stress to the two species, expressed by significant increases in H 2 O 2 , malondialdehyde (MDA), and protein oxidation (p < 0.05). Stress-induced oxidative damages were more pronounced in N. muscorum , yet the two cyanobacterial species showed higher levels (p < 0.05) of antioxidant metabolites and antioxidant enzymes to combat oxidative stress. Compared to N. muscorum , A. laxa invested more in the induction of antioxidant metabolites including FRAP, polyphenols, flavonoids, and glutathione (GSH), as well as in antioxidant enzymes such as POX, CAT, GR, and GPX. Overall, A. laxa species could be exploited as efficient biomarkers for monitoring PtNPs-induced ecotoxicology. Further investigation of bio-absorption and uptake of PtNPs by microalgae is recommended for developing algae-based bioremediation technologies. [Display omitted] • Impact of PtNPs on two cyanobacterial species was investigated. • PtNPs reduced the levels of chlorophylls in cyanobacterial species. • PtNPs induced dose-dependent oxidative stress to the two cyanobacterial species. • Stress-induced oxidative damages were more pronounced in N. muscorum. • A. laxa can be used as a biomarker for monitoring PtNPs-induced toxicology. [ABSTRACT FROM AUTHOR]