A novel electrochemical enzyme biosensor for detection of 17β-estradiol by mediated electron-transfer system.

Abstract An extremely sensitive enzyme sensor for detection of 17β-estradiol based on electropolymerized L -lysine molecules on a glassy carbon electrode (GCE) modified with critic acid@graphene (CA-GR) and cross-linked with laccase enzyme has been developed in this work. As the laccase immobilization, glutaraldehyde was chosen as cross-linker through the groups reactions. The novel enzyme sensor could recognize and determinate 17β-estradiol effectively. The morphology of the enzyme modified electrode was characterized by transmission electron microscopy (TEM) and electron microscopy (SEM). The amino interaction between cross-linker and enzyme was characterized by Fourier transform infrared spectroscopy (FTIR). Under the optimal experimental conditions, good linear relationships were achieved in the range of 4 × 10–13 − 5.7 × 10–11 M and a limit of detection as low as 1.3 × 10–13 M. Moreover, the enzyme sensor exhibited good reproducibility, stability and high selectivity to 17β-estradiol. Excellent performance was showed in the human urine samples analysis, thus confirming great prospect for further application in clinic diagnosis and biological research. Graphical abstract 1. The preparation of the Lac/Poly L -lysine/CA-GR/GCE 2. The electrocatalytic mechanism proposed for the enzyme biosensor. fx1 Highlights • A enzyme biosensor was developed for ultra-trace 17β-estradiol detection based on Lac/PLLY/CA-GR/GCE. • The bio-film Poly L-lysine coated laccase enzyme molecules that generated stable three-dimensional structure and attracted more mediator to catalyze the oxidation of estradiol. • The Poly L-lysine films were used to achieve better conductivity and linking with laccase enzyme more solid than self-assembly monolayers. • L-lysine, amino acids, also can be served as a matrix for developing other enzyme sensors. [ABSTRACT FROM AUTHOR]