A highly sensitive of electrochemical biosensor based on new aptamer sequence for 17α-ethinylestradiol detection in water

The remarkable features of aptamer as biological agent in detecting various compound with high binding affinity could be useful in monitoring of 17 alpha-ethinylestradiol (EE2). EE2 is considered as an endocrine disrupting compound due its ecotoxicity and has widespread in the aquatic ecosystem due to improper disposal. Hence, there is a pressing requirement for sensitive and selective detection of EE2. In this study, we developed a new electrochemical biosensor based on modified DNA aptamers and gold nanoparticles/poly(n-butyl acrylate-co-Nacryloxysuccinimide) microspheres (Au/P(nBA-NAS)). The DNA aptamers was truncated from a 76-mer sequence to 39-mer sequences via computational method, has showed improved binding affinity and stability for EE2. The biosensor was fabricated by attaching the aptamers to the Au/P(NBA-NAS) microspheres, which is provided a large surface area and enhanced electron transfer for the immobilization and signal amplification of the aptamers. The detection principle of the [Fe(CN)6]- 3/- 4 redox probe in differential pulse voltammetry (DPV) measurement by the presence of aptamer-EE2 complexes on the electrode surface. The biosensor exhibited a linear relationship between the current decrease and the EE2 concentration in the range of 1 x 10-6 M to 1 x 10-12 M, with a detection limit of 1.7 x 10-13 M. The biosensor exhibited excellent selectivity, repeatability, and recovery for detecting EE2 in real samples, with results that closely matched those obtained using the highperformance liquid chromatography (HPLC) technique. This study provided a promising alternative for developing aptamer-based sensors for onsite environmental monitoring.