Optimized dendrimer-encapsulated gold nanoparticles and enhanced carbon nanotube nanoprobes for amplified electrochemical immunoassay of E. coli in dairy product based on enzymatically induced deposition of polyaniline
Optimized dendrimer-encapsulated gold nanoparticles and enhanced carbon nanotube nanoprobes for amplified electrochemical immunoassay of E. coli in dairy product based on enzymatically induced deposition of polyaniline
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DOI：
10.1016/j.bios.2016.02.043
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发表时间：
2016-06-15
影响因子：
12.6
通讯作者：
He, Yunyao
中科院分区：
文献类型：
--
作者：
Zhang, Xinai;Shen, Jianzhong;He, Yunyao
基于辣根过氧化物酶（HRP）标记聚苯胺（PAn）的电化学检测，建立了一种检测乳制品中大肠杆菌的高灵敏度免疫传感器。本文以聚酰胺-胺树状大分子包埋的金纳米粒子（PAMAM（Au））为传感平台，研制了免疫传感器。重要的是，HAuCl 4/PAMAM的最佳比例进行了研究，以设计高效的PAMAM（Au）纳米复合材料。纳米复合材料被证明不仅增加了固定化捕获抗体（（c）Ab）的量，而且加速了电子转移过程。此外，利用多壁碳纳米管（CNTs）的放大效应，负载检测抗体（（d）Ab）和大量HRP标记物，制备了{（d）Ab-CNT-HRP}纳米探针。经夹心免疫反应后，定量捕获的纳米探针可催化苯胺氧化生成电活性聚苯胺，用于电化学检测。基于PAMAM（Au）免疫传感器和{（d）Ab-CNT-HRP}纳米探针的信号放大作用，该方法显示PAn的峰电流与E.大肠杆菌浓度范围为1.0 × 10 ~（2）~ 1.0 × 10 ~（6）cfu·mL ~（-1），检出限为50 cfu·mL ~（-1）（S/N=3）;大肠杆菌中，3 h即可达到目的。用该电化学免疫传感器检测了大肠杆菌。方法简便、快速、准确，回收率在96.8%~ 108.7%之间。总之，该方法为大肠杆菌提供了一个有用的方案。该方法具有灵敏度高、准确性好、稳定性好等特点，为乳制品质量评价提供了有力的工具。(C)© 2016 Elsevier B. V.版权所有。
A highly sensitive immunosensor was reported for Escherichia coli assay in dairy product based on electrochemical measurement of polyaniline (PAn) that was catalytically deposited by horseradish peroxidase (HRP) labels. Herein, the immunosensor was developed by using poly(amidoamine) dendrimer-encapsulated gold nanoparticles (PAMAM(Au)) as sensing platform. Importantly, the optimal HAuCl4/PAMAM ratio was investigated to design the efficient PAMAM(Au) nanocomposites. The nanocomposites were proven to not only increase the amount of immobilized capture antibody ((c)Ab), but also accelerate the electron transfer process. Moreover, the {(d)Ab-CNT-HRP} nanoprobes were prepared by exploiting the amplification effect of multiwalled carbon nanotubes (CNTs) for loading detection antibody ((d)Ab) and enormous HRP labels. After a sandwich immunoreaction, the quantitatively captured nanoprobes could catalyze oxidation aniline to produce electroactive PAn for electrochemical measurement. On the basis of signal amplification of the PAMAM(Au)-based immunosensor and the {(d)Ab-CNT-HRP} nanoprobes, the proposed strategy exhibited a linear relationship between the peak current of PAn and the logarithmic value of E. coli concentration ranging from 1.0 x 10(2) to 1.0 x 10(6) cfu mL(-1) with a detection limit of 50 cfu mL(-1) (S/N=3), and the electrochemical detection of E. coli could be achieved in 3 h. The electrochemical immunosensor was also used to determine E. coli in dairy product (pure fresh milk, infant milk powder, yogurt in shelf-life and expired yogurt), and the recoveries of standard additions were in the range of 96.8-108.7%. Overall, this method gave a useful protocol for E. coli assay with high sensitivity, acceptable accuracy and satisfying stability, and thus provided a powerful tool to estimate the quality of dairy product. (C) 2016 Elsevier B.V. All rights reserved.