A Fetomolar Level 17β-estradiol Electrochemical Aptasensor Constructed On Hierachical Dendritic Gold Modified Boron-Doped Diamond Electrode

It is of great significance to develop efficient monitoring strategies with high sensitivity and selectivity for 17β-estradiol (E2), a typical steroidal hormones endocrine disrupting chemicals, in water samples. Here reports a novel practical electrochemical impedance aptasensor for the detection of E2 effectively and fast. A unique hierachical dendritic gold microstructure is constructed on boron doped diamond (BDD) electrode surface through a double template method. The obtained dendritic Au/BDD electrode has lower background current, better electrochemical performance and higher capacity to immobilize biomolecules. E2 aptamers which can specifically binding to E2 were immobilized on the surface of the dendritic Au/BDD electrode through Au-S interaction, obtaining a newly-typed E2 aptasensor. The aptasensor performed supersensitive and specific recognition capacity towards E2. Once E2 enters into the detecting system, it reacts with aptamers and enlarges the interfacial electron transfer resistance significantly, which leads to the increment of impedance signal and realizes the quantification of E2. Results show that the constructed E2 aptasensor exihbits a wide linear range with the logarithm of concentration of E2 from 1.0 × 10−14 to 1.0 × 10−9 mol/L with a femtomolar level detection limit of 5.0 × 10−15 mol/L. High specificity is also evidenced by control experiments performed with the E2 aptasensor in a co-existing system including estriol, bisphenol A, nonyl phenol, diethyl phthalate, resorcinol and atrazine. Real water sample analysis showed the reliability and potential in practical environmental monitoring of the aptasensor. Besides, the aptasensor is easy to prepare, and the dendritic Au/BDD electrode can be a promising platform for design of other sensors.