A novel PAMAM-Au nanostructure-amplified CdSe quantum dots electrochemiluminescence for ultrasensitive immunoassayby Kai Chen, Zhengkun Lu, Yingqiang Qin, Guifen Jie

Journal of Electroanalytical Chemistry

About

Year
2015
DOI
10.1016/j.jelechem.2015.07.012
Subject
Analytical Chemistry / Electrochemistry / Chemical Engineering (all)

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A novel PAMAM-Au nanostructure-amplified CdSe quantum dots electrochemiluminescence for ultrasensitive immunoassay

Kai Chen, Zhengkun Lu, Qingmin Meng, Yingqiang Qin, Guifen Jie

PII: S1572-6657(15)30016-3

DOI: doi: 10.1016/j.jelechem.2015.07.012

Reference: JEAC 2180

To appear in:

Received date: 21 May 2015

Revised date: 28 June 2015

Accepted date: 9 July 2015

Please cite this article as: , A novel PAMAM-Au nanostructure-amplified CdSe quantum dots electrochemiluminescence for ultrasensitive immunoassay, (2015), doi: 10.1016/j.jelechem.2015.07.012

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A novel PAMAM-Au nanostructure-amplified CdSe quantum dots electrochemiluminescence for ultrasensitive immunoassay

Kai Chen, Zhengkun Lu, Qingmin Meng, Yingqiang Qin, Guifen Jie 

Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, Qingdao University of Science and Technology, 266042, P. R. China

Abstract

A novel PAMAM dendrimers-Au nanostructure was prepared and used to develop an amplified

CdSe quantum dots (QDs) probe for ultrasensitive electrochemiluminescence (ECL) immunoassay.

The unique dendrimer-encapsulated Au nanoparticles have numerous functional groups for loading enough QDs, and the ECL of QDs was enhanced by the localized surface plasmon resonance (LSPR) of gold nanoparticles (Au NPs). After the PAMAM dendrimer was used to form an effective immobilization matrix for biomolecules, the capture antibody (Ab1) was covalently conjugated to the dendrimers. In the presence of the target human IgG (Ag), the secondary antibody (Ab2) modified PAMAM-Au-CdSe QDs signal probe was attached to the electrode. On the basis of the amplified ECL signal of the CdSe QDs, an ultrasensitive signal-on ECL immunosensor was developed. The PAMAM-Au-CdSe QDs nanostructure opens a new promising material direction for ECL biosensing, this method shows considerable promise for diverse clinical applications.

Keywords: dendrimers-Au; nanostructure; electrochemiluminescence; immunosensor 1. Introduction

Electrogenerated chemiluminescence (ECL) that combines electrochemical and luminescent methods has proved to be a powerful analytical technique for clinical diagnostics immunoassay [1] 

Corresponding author. Tel.: +86-532-84022750; Fax: +86-532-84022750.

E-mail: guifenjie@126.com

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ACCEPTED MANUSCRIPT 2 and DNA analysis, [2] environmental assays, [3] as well as food and water testing. [4]

In the past decade, many kinds of semiconductor-based quantum dots (QDs) have been found to have ECL activity, [5] and a series of analytical applications have been developed based on the ECL behaviors of those QDs. [6]

However, ECL signal of pure QDs is usually lower than that of luminal or

Ru(bpy)3 2+ , which is unable to meet the requirements of early diagnosis of low-abundance biomarkers. Thus, signal amplification strategies have been developed for ECL trace analysis. The development of novel QDs nanostructure to enhance ECL is of great significance in ECL bioassays.

Signal amplification for ECL mainly involves three levels: the matrix, the luminescence quantum efficiency of signal labels, and the number of signal labels. Carbon materials (such as carbon nanotubes, [7] graphene, [8] carbon sphere [9] and carbon nanofiber [10] and noble metal nanostructures are usually used as effective matrix for the indirect signal amplification. [11]

In our previous work, an amplified QDs ECL signal probe was developed by using silver-cysteine hybrid nanowires. [12]

Gold nanoparticles (GNPs) have attracted much attention in different immunoassay due to their unique physical and chemical properties, such as easily controllable size distribution, long-term stability, and friendly biocompatibility with immunospecies. Gold nanoparticles and carbon nanotubes were reported to enhance QDs ECL. [13]

Recently, dendrimers polyamidoamine (PAMAM), the regular tree-like high branched macromolecules, are receiving considerable attention for applications in chemical and biological areas owing to their numerous functional amino groups. [14]

It is reported that a unique dendrimers/QDs nanocluster was used to develop an amplified QDs ECL signal probe for cells assays. [6c]

A PAMAM-Au/carbon nanotubes nanostructure was used to provide a favorable environment for AChE modification with electrocatalytic characteristics. [15]

So far, the PAMAM dendrimers-Au nanostructure has not been applied to amplify QDs ECL or develop ECL probe, though they have promising advantages due to numerous functional groups as well as excellent electroconductibility.

In this work, we have prepared a new PAMAM-Au nanostructure and used to develop the amplified CdSe QDs ECL probe for ultrasensitive signal-on ECL immunoassay. The dendrimer-encapsulated Au nanoparticles have numerous functional groups for loading enough

QDs, and the Au nanoparticles much accelerate the process of ECL reaction due to good conductibility, so ECL signal amplification could be achieved. On the basis of sandwich immunoreaction strategy, the amplified Ab2-PAMAM-Au-QDs ECL signal probe was applied to the sensitive ECL immunosensing of human IgG. 2. Experimental 2.1 Syntheses of dual-stabilizers-capped CdSe QDs

CdSe QDs were synthesized according to the literature. [16]

Briefly, CdCl2 solution (0.20 M, 0.80 mL), HMP (72.5 mg), and MPA (34.6 μL) were dissolved in 50 mL of H2O successively.

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Then, pH was adjusted to 9.0, and Na2SeO3 solution (20.0 mM, 0.80 mL) was added to the mixture. After being refluxed at 100 °