Determination of 17β-estradiol by surface-enhanced Raman spectroscopy merged with hybridization chain reaction amplification on Au@Ag core-shell nanoparticles
The authors describe an aptamer-based assay for 17β-estradiol. It relies on the combined use of surface enhanced Raman scattering (SERS) and hybridization chain reaction (HCR). The aptamer against 17β-estradiol is applied as the recognition probes, and this results in excellent specificity. Specific recognition of target 17β-estradiol induce the freedom of DNA 2, which will open the stem-loop structure of probe 1 on the Au@Ag and form the partial dsDNA structure. With the nicking enzyme, the partial dsDNA will be hydrolyzed and the reside ssDNA on Au@Ag will form a small stem-loop structure. With the help of the other probe 2 modified Au@Ag and pre-immobilized probe 3 on the well of the microplate, an enzyme-free HCR can occur and tremendous Au@Ag can be assembled along the formed dsDNA in HCR, which can act as the excellent substrate for Raman measurement and greatly amplify the Raman signal of R6G on the Au@Ag. Afterwards, the key factor, ratio between probe 2-Au@Ag (P2) and probe1-Au@Ag (P1), affects the detection sensitivity is systematically optimized for the best sensing performance. The SERS signal of R6G, best measured at 1651 cm−1, increases linearly in the wide range from 1 pM to 10 nM. The detection limit can be as low as 0.1 pM.
KeywordsEstrogen Aptamer SERS Hybridization chain reaction Signal amplification Gold nanoparticle Environment monitoring Food safety
This work is financially supported by the grant of 2017YFF0208600, the NSFC Grant of 21475030, Open Foundation of Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization of EWPL201701, the China Agriculture Research System-48 (CARS-48), Anhui Provincial Modern Argo-industry Tech. Research System (NYCYTX-2016-84) and the Fundamental Research Fund for central university (Grants No. 2017HGPA0162, JZ2018HGTA0205, PA2017GDQT0018).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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