Camil Rex M, Manshi Kumari Gupta, Chinnappan Sudandiradoss, Amitava Mukherjee
Microplastics and nanoparticles are emerging contaminants in the marine system. Although UV-A radiation is environmentally relevant, most ecotoxicity studies overlook its role in modulating contaminant toxicity. Therefore, this study aimed to investigate the trophic transfer potential of titanium dioxide nanoparticles (TiO2-NPs) in the absence and presence of amine (NH2 MPs) and carboxyl (COOH MPs) functionalized polystyrene microplastics (PS-MPs) under both visible-light and UV-A radiation. The experiments were performed using marine microalgae Chlorella sp. and marine crustacean Artemia salina, representing the producer-consumer food chain. Bio-uptake of Ti in Chlorella sp. was higher under UV-A treatment than under visible-light illumination. Bio-uptake of Ti in Chlorella sp. was higher in the absence of PS-MPs. A comparable pattern was observed in the bio-uptake of Ti in A. salina following dietary exposure. Consequently, A. salina fed with microalgae pre-treated with TiO2-NPs reduces survival, enhances oxidative stress, and alters neurotransmitter activity. In contrast, in the presence of PS-MPs, these detrimental effects exhibited by TiO2-NPs were reduced. In silico studies with acetylcholinesterase provided complementary mechanistic insights into the observed neurotoxicity. Under both light treatments, the biomagnification factor for TiO2-NPs and TiO2-NPs + PS-MPs was < 1, indicating no biomagnification from Chlorella sp. to A. salina. Risk quotient analysis revealed the higher ecological risk posed by the TiO2-NPs. Pearson correlation and the cluster heatmap revealed that oxidative stress and altered neurotransmitter activity may have impaired A. salina survival. Overall, this study shows how light and microplastics modulate the trophic transfer potential and toxicity of TiO2-NPs in marine organisms.