Metal ions-based immunosensor for simultaneous determination of estradiol and diethylstilbestrol

• First used to simultaneously detect the estradiol and diethylstilbestrol.
• Fe3O4–NH2 adsorbed Pb2+ and Cd2+ as labels for two analytes detection.
• Signals were achieved by the stripping method after Hg2+ forming amalgam with metal ions.
• Wide linear from 0.050 pg mL−1 to 100 ng mL−1 and 1.0 pg mL−1 to 100 ng mL−1.
• The detection limits reached 0.015 pg mL−1 and 0.38 pg mL−1.

Environmental estrogens (EEs) can cause various endocrine diseases. Herein, we designed an ultrasensitive electrochemical immunosensor for simultaneous detection of two typical EEs, estradiol and diethylstilbestrol. These two analytes were immobilized on graphene sheet (GS) modified glassy carbon electrode (GCE). Amino-group functionalized mesoporous Fe3O4 (Fe3O4–NH2) was loaded with Pb2+ or Cd2+, and then incubated with estradiol and diethylstilbestrol antibodies, respectively. Using an electrochemical analysis technique, two well-separated peaks were generated by the redox reaction of Pb2+ or Cd2+, making the simultaneous detection of two analytes on the electrode possible. Subsequently, square wave anodic stripping voltammetry (SWASV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behaviors of the immunosensor. Under optimized conditions, the SWASV peak currents were proportional to the concentrations of estradiol and diethylstilbestrol in the range from 0.050 pg mL−1 to 100 ng mL−1 and 1.0 pg mL−1 to 100 ng mL−1, respectively. The immunosensor exhibited highly sensitive response to estradiol with a detection limit of 0.015 pg mL−1 and diethylstilbestrol with a detection limit of 0.38 pg mL−1. Furthermore, the immunosensor was satisfactorily employed to detect estradiol and diethylstilbestrol simultaneously in water samples.