A rapid receptor–ligand assay determination of estrogens using surface plasmon resonance

A rapid and simple assay has been developed for the determination of estrogen and estrogen like compounds using surface plasmon resonance (SPR) that might be of use in epidemiological studies and potentially may aid the diagnosis of male infertility. The interaction between hER and an immobilised estradiol-BSA conjugate can be suppressed if the receptor is pre-incubated with estradiol or with the estrogen mimic, diethylstilbesterol (DES). The binding response of hER to immobilised estradiol-BSA was 184±40 (n=3) resonance units (RU). When preincubated with either free estradiol or DES, the response was reduced to 93±8 and 103±19 RU, respectively (P≤0.018). There was no significant difference in the extent to which the level of binding was reduced when these two compounds were compared (P=0.47). When receptor was pre-incubated with estradiol to establish if binding of the receptor to a zearlenone-BSA (Z-BSA) conjugate also decreased, there was a substantial decrease in binding to Z-BSA, the difference in response being significant (P=0.034). The increased speed with which data may be obtained using SPR compared with traditional biological assays permits greater sample throughput and provides a more quantitative approach to defining levels of estrogen and estrogen like compounds in body fluids.