Competitive ECL immunosensor for ultrasensitive 17β-estradiol detection based on synergistic promotion strategy using CdSe–ZnSe nanocomposites

A novel competitive ECL immunosensor for detection of 17β-Estradiol (E2) has been fabricated successfully. CdSe–ZnSe nanocomposites (CdSe–ZnSe NCs) with high catalytic properties, large surface area and good conductivity were used synergistically as the ECL nanocarriers of Pt nanoparticles (PtNPs). The ECL intensity of CdSe–ZnSe NCs increased and stabilized with luminol-PtNPs (luminol-PtNPs@CdSe–ZnSe NCs) because of electron transfer. To achieve the successful assembling of competitive ultrasensitive ECL immunosensor with high sensitivity and synergistic effect, Ag@TiO2 core-shell was introduced as label. Ag@TiO2 acted as a signal amplifier and also exhibited the high catalytic activity towards H2O2. This firmly anchored the E2 Antigen with covalent bond and converted the longer wavelength radiations to shorter wavelength. Under optimized conditions, our proposed strategy quantify the selective and reliable analysis of E2 with detection limit of 2.51 fg/mL (S/N = 3) within the linear range of 0.0001–30 ng/mL. The assembled synergistic strategy-based ECL immunosensor manifested the promising sensitivity, selectability along with high level of repeatability. Thus, the fabricated ECL immunosensor has potential valuable application for E2 detection along with many other environmental pollutants.