The association between nC(60) and 17 alpha-ethinylestradiol (EE2) decreases EE2 bioavailability in zebrafish and alters nanoaggregate characteristics

Manufactured nanoparticles (NPs) released into surface waters will associate with other substances and these interactions may affect environmental fate and bioavailability of NPs and the associated substances. We investigated the association between aqueous aggregates of C-60 (nC(60)) and synthetic estrogen, 17 alpha-ethinylestradiol (EE2), and considered nC(60) physicochemistry and EE2 bioavailability (by measuring vitellogenin (vtg1A/B) gene expression) in zebrafish. Bioavailability of EE2 was reduced with increasing concentration of nC(60) (P <0.05), and bioavailability of EE2 decreased further after aging 28 d with nC(60). Reduction in EE2 bioavailability was correlated with computed surface area of nC(60), and reduced bioavailability of EE2 upon aging was consistent with absorption of EE2 within nC(60) aggregates. Size and zeta potential of nC(60) particles were affected by EE2 (1 mu g/L) and also by aging (28 d) in aqueous phase. Results indicate that nC(60) can reduce bioavailability of some substances and influence environmental fate and transport of associated substances.