Selective detection of 17β-estradiol in water using an upconversion luminescence–based Förster resonance energy transfer aptasensor

Consistent exposure to 17β-estradiol (E 2 ) through water and food sources presents considerable health hazards, necessitating the development of sensitive E 2 detection methods. Herein, an E 2 nanosensor based on Förster resonance energy transfer (FRET) was developed by immobilizing amino-SiO₂-modified upconversion nanoparticle (UCNP) core–shell structures functionalized with E 2 -specific aptamers on graphene oxide (GO) nanosheets. The aptamers adsorbed onto GO via π–π stacking, facilitating the FRET-induced upconversion luminescence quenching. Upon E 2 addition, the aptamers detached from GO, restoring the UCL intensity. The as-developed nanosensor exhibited a strong linear response to E 2 concentrations in the range of 10–200 ng/mL and a detection limit of 6.39 ng/mL. Furthermore, the high recovery rates (88–98 %) of the sensor validated its reliability. The fabricated sensor demonstrated excellent potential for the accurate detection of E 2 in aqueous environments.