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An electrochemical sandwich immunosensor for cardiac troponin I by using nitrogen/sulfur co-doped graphene oxide modified with [email protected] nanocubes as amplifiers

Authors
  • Lv, Hui1
  • Zhang, Xiaobo1
  • Li, Yueyun1
  • Ren, Yong2
  • Zhang, Chunyan1
  • Wang, Ping1
  • Xu, Zhen1
  • Li, Xinjin1
  • Chen, Zhiwei3
  • Dong, Yunhui1
  • 1 Shandong University of Technology, School of Chemistry and Chemical Engineering, Zibo, 255049, People’s Republic of China , Zibo (China)
  • 2 Zibo Normal College, Department of Mathematical Sciences, Zibo, 255130, People’s Republic of China , Zibo (China)
  • 3 Shandong University of Technology, School of Life Science, Zibo, 255049, People’s Republic of China , Zibo (China)
Type
Published Article
Journal
Microchimica Acta
Publisher
Springer-Verlag
Publication Date
Jun 11, 2019
Volume
186
Issue
7
Identifiers
DOI: 10.1007/s00604-019-3526-2
Source
Springer Nature
Keywords
License
Yellow

Abstract

A voltammetric sandwich immunoassay is described for the biomarker cardiac troponin I (cTnI). The gold nanocube-functionalized graphene oxide (AuNC/GO) is employed as a substrate to accelerate the electron transfer and to immobilize more primary antibodies. It also employs composite materials prepared from bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide as the signal amplifier. The introduction of N and S into GO enlarges the active surface and accelerates the electron transfer rate. Such unique characteristics render the material an effective support substrate to load more [email protected] and to immobilize an increasing number of second antibodies via Ag-N bonds. After specific binding with cTnI, the immunosensor was incubated in a labeled cTnI secondary antibody solution. The amperometric signal change is then measured at 0.34 V (vs. SCE) using o-phenylenediamine and hydrogen peroxide as an electrochemical probe. Response is linear in the concentration range from 100 fg∙mL−1 to 250 ng∙mL−1, and the detection limit is 33 fg∙mL−1. Graphical abstractSchematic presentation of cardiac troponin I (cTnI) electrochemical immunosensor based on gold nanocube-functionalized graphene oxide (AuNC/GO) as substrate material, bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide ([email protected]/N, S-rGO) as signal amplifier, and hydrogen peroxide (H2O2) and o-phenylenediamine (o-PD) as redox probe.

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