A high throughput screening method of endocrine disrupting chemicals in tap water and milk samples based on estrogen receptor α and gold nanoparticles
Increasing concern of endocrine disrupting chemicals (EDCs) in environment and food samples has aroused a demand for rapid and high throughput screening methods to evaluate their estrogenic effects. In this study, a sensitive assay based on estrogen receptor α (ERα) and gold nanoparticles (AuNPs) was established to screen EDCs and confirm the binding affinities of EDCs with ERα. ERα protein can prevent salt-induced aggregation of AuNPs by recruiting Na+ from AuNPs. When there are EDCs as targets in the sample, the specific binding of ERα and EDCs via hydrogen bond results in a reduction of the binding between Na+ and ERα and then most Na+ bind to AuNPs and induce their aggregation. Nine kinds of estrogen-agonist compounds, 17β-estradiol (17β-E2), diethylstilbestrol (DES), hexoestrolum (HES), 17α-estradiol (17α-E2), estrone (E1), 2,2-bis(4-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), genistein, bisphenol A (BPA) and bisphenol B (BPB), were chosen as the representative targets for validation of this method. The rank order of estrogenic potency determined by this method was DES > 17β-E2 > HES > 17α-E2 > E1 > HPTE > genistein > BPA > BPB, which were consistent with the published results. Moreover, the recoveries of nine kinds of EDCs spiked in tap water and milk samples were both between 80.0% and 120.0%, which proved that this method can be used for high throughput screening of these EDCs in environment and food samples.