Autofluorescence-Free Immunoassay Using X‑ray Scintillating Nanotags

Autofluorescence background in complex biological samples is a major challenge in achieving high sensitivity of fluorescence immunoassays (FIA). Here we report an X-ray luminescence-based immunoassay for high-sensitivity detection of biomarkers using X-ray scintillating nanotags. Due to the weak sca...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2018-06, Vol.90 (11), p.6992-6997
Main Authors: Ou, Xiang-Yu, Guo, Tao, Song, Liang, Liang, Han-Yu, Zhang, Qi-Zhao, Liao, Jia-Qi, Li, Jing-Ying, Li, Juan, Yang, Huang-Hao
Format: Article
Language:English
Subjects:
Absorption
Alpha rays
Analytical chemistry
Background radiation
Biological properties
Biomarkers
Chemistry
Chromophores
Energy conversion efficiency
Fluorescence
Gadolinium
Immunoassay
Luminescence
Multiplexing
Nanoparticles
Photons
Sensitivity
X ray sources
X-rays
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Summary:Autofluorescence background in complex biological samples is a major challenge in achieving high sensitivity of fluorescence immunoassays (FIA). Here we report an X-ray luminescence-based immunoassay for high-sensitivity detection of biomarkers using X-ray scintillating nanotags. Due to the weak scattering and absorption of most biological chromophores by X-ray excitation, a low-dose X-ray source can be used to produce intense scintillating luminescence from the nanotags for autofluorescence-free biosensing. To demonstrate this concept, we designed and synthesized NaGdF4:Tb@NaYF4 core/shell nanoparticles as kind of high-efficiency X-ray scintillating nanotags, which are able to convert high-energy X-ray photons to visible light without autofluorescence in biological samples. Notably, strong X-ray absorption and minimized surface quenching arising from the heavy Gd3+/Tb3+ atoms and core/shell architecture of the nanoparticles were found to be critically important for high-efficiency X-ray excited luminescence for high-sensitivity biosensing. Our method allows for sensing alpha-fetoprotein (AFP) biomarkers with a detection limit down to 0.25 ng/mL. Moreover, the as-described X-ray luminescence immunoassay exhibited an excellent biological specificity, high stability, and sample recovery, implying an opportunity for applications in complex biological samples. Consequently, our method can be readily extended for multiplexing sensing and medical diagnosis.
ISSN:0003-2700
1520-6882
DOI:10.1021/acs.analchem.8b01315