Effects of titanium oxide nanoparticles on growth, biochemical composition, and photosystem mechanism of marine microalgae Isochrysis galbana COR-A3

The widespread utilization of titanium oxide nanoparticles (TiONPs) in various industrial applications has raised concerns about their potential ecological risks in marine environment. Assessing the toxicity of TiONPs on primary producers is essential to understand their impact on marine ecosystem. This study investigates the acute toxicity effect of TiONPs on Isochrysis galbana COR-A3 cells, focusing on structural and physiological changes that can compromise algal viability and ecological function. Cells were exposed to TiONPs concentration of 10-50 mg/L and assessments were conducted over 96 h to evaluate cell viability, biochemical composition, photo-physiology, oxidative stress and morphological deformations. At 50 mg/L concentration, cell viability was significantly reduced by 73.42 ± 3.46% and subsequent decrease of 42.8%, 29.2%, 44.2% in carbohydrate, protein and lipid content were observed. TiONPs exposure elevates the reactive oxygen species production and thereby impairing the photosystem II efficiency and disrupting the cellular metabolism. Morphological analysis revealed significant cell membrane disruption and plasmolysis. These cascading effects reveal TiONPs ability to interfere with algal physiological process, potentially affecting the primary productivity in marine ecosystem. Our findings highlight the ecological risk associated with the TiONPs, emphasizing the need for regulatory measures to mitigate the nanoparticle pollution in aquatic environment. This study provides more insights on the TiONPs induced toxicity in marine microalgae by altering the photosynthetic performance and biochemical integrity.