Optical fiber immunosensor based on graphene oxide and biotin–streptavidin(SA) signal amplification system for rapid and sensitive detection of 17β-estradiol(E2)

With the increasing pollution of endocrine disruptors (EDCs) to water and the development of optical fiber sensing technology, it is necessary to develop new biosensors with simplicity, sensitivity and high specificity. Herein, we demonstrated an EDCs detection device based on graphene oxide (GO) functionalized S optical fiber taper (SFT) and biotin–SA signal amplification system for the detection of E2 concentrations in water samples. In this study, the sensing element was based on compact SFT that was obtained by fusing optical fiber through a fusion splicer. The immunosensor probe was constructed by functionalizing the SFT with GO using self-assembled technique, further coupling with streptavidin and specific biotinylated monoclonal antibody against E2. The mechanism of detecting E2 relies on measuring the external refractive index changes of STF induced by the target adsorption of analyte onto the antibody. In addition, we also prepared an optical fiber immunosensor without amplification signal system as a control. By experiment, we gained an optical fiber immunosensor with a high sensitivity value of 38.3 nm/(ng/mL) that was about 1.5 times better than that of the control immunosensor produced, which was due to the signal amplification, high biotin affinity and strong specificity of SA. The detection limit of (LOD) the immunosensor for E2 was 0.01ng/mL (S/N= 3). The results revealed that the developed optical fiber immunosensor was successfully applied to the fast, online, low cost and sensitive detection of E2 in environmental samples, and its detection effect is better than the control optical fiber immunosensor