Titanium (IV) oxide anatase nanoparticles as vectors for diclofenac: Assessing single and combined oxidative stress-related toxicity in the aquatic macrophyte Egeria densa

Abstract Titanium dioxide, frequently used in commonplace products, is now regularly detected in aquatic environments. Understanding its toxic effects on native biota is essential; however, combined toxicity with commonly occurring pollutants, such as the pharmaceutical diclofenac, may provide more insight into environmental situations. Therefore, the present study aimed to evaluate the effects of titanium dioxide and diclofenac, individually and combined, on the macrophyte Egeria densa. DCF uptake and removal were assessed. DCF and titanium dioxide toxicity were evaluated by assaying enzymes as bioindicators of biotransformation and oxidative stress. Cytosolic glutathione S-transferase and glutathione reductase activities were increased by diclofenac, titanium dioxide, and the combination. Both enzymes’ activities were more significantly elevated by diclofenac and the combination than nanoparticles alone. Microsomal glutathione S-transferase was unaffected by diclofenac exposure but inhibited with titanium dioxide and the mixture. Diclofenac elicited the most significant response. Based on the macrophytes’ vitality, the cytosolic enzymes effectively prevented damage.