期刊
ANALYTICAL CHEMISTRY
卷 86, 期 24, 页码 12398-12405出版社
AMER CHEMICAL SOC
DOI: 10.1021/ac504027d
关键词
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资金
- National Natural Science Foundation [21375059, 21175065, 21335004, 21121091]
- National Basic Research Program of China [2011CB933502]
An ultrasensitive photoelectrochemical sandwich immunoassay was developed to detect matrix metalloproteinase-2 (MMP-2, antigen, Ag) based on CdS:Mn/CdTe cosensitized TiO2 nanotubes (TiO2-NTs) and signal amplification of SiO2@Ab(2) conjugates. Specifically, the TiO2-NTs electrode was first deposited with CdS:Mn by successive ionic layer adsorption and reaction technique and then further coated with CdTe quantum dots (QDs) via the layer-by-layer method, forming TiO2-NTs/CdS:Mn/CdTe cosensitized structure, which was employed as a matrix to immobilize capture MMP-2 antibodies (Ab(1)); whereas, SiO2 nanoparticles were coated with signal MMP-2 antibodies (Ab(2)) to form SiO2@Ab(2) conjugates, which were used as signal amplification elements via the specific antibody-antigen immunoreaction between Ag and Ab(2). The ultrahigh sensitivity of this immunoassay derived from the two major reasons as below. First, the TiO2-NTs/CdS:Mn/CdTe cosensitized structure could adequately absorb the light energy, dramatically promote electron transfer, and effectively inhibit the electron-hole recombination, resulting in significantly enhanced photocurrent intensity of the sensing electrode. However, in the presence of target Ag, the immobilized SiO2@Ab(2) conjugates could evidently increase the steric hindrance of the sensing electrode and effectively depress the electron transfer, leading to obviously decreased photocurrent intensity. Accordingly, the well-designed photoelectrochemical immunoassay exhibited a low detection limit of 3.6 fg/mL and a wide linear range from 10 fg/mL to 500 pg/mL for target Ag detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising platform for the detection of other important biomarkers.
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