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FeS 2 −AuNPs Nanocomposite as Mimicking Enzyme for Constructing Signal‐off Sandwich‐type Electrochemical Immunosensor Based on Electroactive Nickel Hexacyanoferrate as Matrix
Author(s) -
Zhang Lina,
Xie Xiyue,
Yuan Yali,
Chai Yaqin,
Yuan Ruo
Publication year - 2019
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201800827
Subject(s) - electrochemistry , detection limit , nanocomposite , electrode , materials science , oxidizing agent , colloidal gold , electrochemical gas sensor , nanoparticle , matrix (chemical analysis) , amperometry , nuclear chemistry , chemical engineering , chemistry , chromatography , nanotechnology , composite material , organic chemistry , engineering
Abstract In this work, a novel sandwich‐type electrochemical immunosensor with electroactive nickel hexacyanoferrate nanoparticles (NiHCFNPs) as matrix was constructed for α‐fetoprotein (AFP) detection in a signal‐off manner by using FeS 2 −AuNPs nanocomposite catalyzed insoluble precipitation to significantly inhibit the electrochemical signal. Initially, the NiHCFNPs with excellent electrochemical property was modified on the electrodeposited nano‐Au electrode to obtain a strong initial electrochemical signal. Subsequently, another nano‐Au layer was formed for immobilization of capture antibody (Ab 1 ). In the presence of target AFP, the prepared FeS 2 −AuNPs‐Ab 2 bioconjugate could be specifically recognized and immobilized on electrode through the sandwich‐type immunoreaction. The FeS 2 with large specific surface areas were used as scaffolds to load abundant mimicking enzyme AuNPs. With the help of hydrogen peroxide (H 2 O 2 ), FeS 2 −AuNPs with peroxidase‐like activity accelerated the 4‐chloro‐1‐naphthol (4‐CN) oxidation with generation of insoluble precipitation on electrode, which would greatly hinder the electron transfer and thus caused the decrease of electrochemical signal for quantitative determination of AFP. This approach achieved a wide dynamic linear range from 0.0001 to 100 ng mL −1 with an ultralow limit detection of 0.028 pg mL −1 . Especially, the proposed AFP immunosensor can be applied to detect human serum samples with satisfactory results, indicating a potential application in clinical monitoring of tumor biomarkers.