A Highly Sensitive Sandwich Immunosensor for Determination of α-Fetoprotein / 分析化学

ABSTRACT

The Au-PDA-Fe3O4 decorated graphene oxide electrode was modified with Prussion blue-secondary antibodies for determination of cancer biomarker α-fetoprotein (AFP) with great sensitivity.Scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible absorption spectrometry were used to characterize the structure of the material.Greatly enhanced sensitivity for the cancer biomarker is based on a dual signal amplification strategy.First, Fe3O4-PDA-Au used for the biosensor platform increased the surface area to capture a large amount of primary antibodies (Ab1), which resulted in amplification of the detection response.Second, graphene oxide allowed several binding events of PB-Ab2.Enhanced sensitivity was also achieved by introducing the multibioconjugates of Ab2-PB-GO onto the electrode surface through sandwich immunoreactions.The test result shows that there are linear relationships between current and AFP concentrations ranging from 0.005 ng/mL to 1 ng/mL and 1 ng/mL to 20 ng/mL, with the low detection limit (LOD) of 1.0 pg/mL.This immunosensor is simple, low-cost and sensitive and shows a great potential in biomedicine, clinical diagnosis and health examination.