An ultrasensitive ECL immunosensor with a dual signal amplification strategy using AuNPs@GO@SmMoSe2 and Gd2(MoO4)3 for estriol detection

Abstract

Background: Estriol (E3) is a common estrogen responsible for regulating the female reproductive system, but excessive amount can pose health risks to humans and wild life. Therefore, sensitive and accurate detection of estriol level is crucial. A novel competitive ECL immunosensor based on a dual signal amplification strategy of AuNPs@GO@SmMoSe₂ and Gd₂(MoO₄)₃ was fabricated for ultrasensitive detection of estriol. Graphene oxide (GO) increased the electric conductivity and surface area of SmMoSe₂ and gold nanoparticles (AuNPs) improved the electrochemical active sites of GO@SmMoSe₂. In order to further amplify the ECL signals, Gd₂(MoO₄)₃ with excellent electron transfer capability were used for binding E3-antigen (Ag). Then, Gd₂(MoO₄)₃-Ag/BSA competed with Standard E3 for limited number of antibodies to construct a competitive ECL immunosensor.

Results: Under optimized condition, the proposed competitive ECL immunosensor was used to detect various concentrations of Standard E3 samples. In addition, the proposed ECL immunosensor showed the high sensitivity for E3 detection in range between 0.001 and 500 ng/mL with the detection limit of 0.0073 ng/mL (S/N = 3). The wider linear range and lower detection limits of the proposed ECL immunosensor might be attributed to outstanding ECL properties of AuNPs@GO@SmMoSe₂ and Gd₂(MoO₄)₃ nanosheets. Furthermore, the proposed competitive ECL immunosensor was also compared with various detection methods. Based on above, the fabricated ECL immunosensor was employed for real sample analysis with acceptable RSD values and recoveries.

Significance: A dual signal amplification strategy enhanced the potential of the well-prepared ECL immunosensor for detecting E3 samples in the real environment. Thereby, the successfully fabricated competitive ECL immunosensor with excellent electrochemical properties, long term storage stability, and high sensitivity and selectivity validated its potential application for environmental monitoring and analysis.

Keywords: AuNPs@GO@SmMoSe(2); Competitive ECL immunosensor; Dual signal amplification; Estriol; Gd(2)(MoO(4))(3).