pH responsive label-assisted click chemistry triggered sensitivity amplification for ultrasensitive electrochemical detection of carbohydrate antigen 24-2

Sensitivity amplification strategy by implementing click chemistry in the construction of biosensing interface can efficiently improve the performance of immunosensor. Herein, we developed a sandwich-type amperometric immunosensor for ultrasensitive detection of carbohydrate antigen 24-2 (CA 242) ba...

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Bibliographic Details
Published in:Biosensors & bioelectronics 2018-09, Vol.115, p.30-36
Main Authors: Zheng, Yun, Zhao, Lihua, Ma, Zhanfang
Format: Article
Language:English
Subjects:
Amperometric immunosensor
Antibodies, Immobilized - chemistry
Antigens, Tumor-Associated, Carbohydrate - chemistry
Antigens, Tumor-Associated, Carbohydrate - isolation & purification
Biosensing Techniques
Click Chemistry
Click reaction
Copper - chemistry
DNA - chemistry
Gold - chemistry
Humans
Hydrogen-Ion Concentration
Limit of Detection
Metal Nanoparticles - chemistry
Polydopamine particles
Sandwich-type
Tumor marker
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Summary:Sensitivity amplification strategy by implementing click chemistry in the construction of biosensing interface can efficiently improve the performance of immunosensor. Herein, we developed a sandwich-type amperometric immunosensor for ultrasensitive detection of carbohydrate antigen 24-2 (CA 242) based on pH responsive label-assisted click chemistry triggered sensitivity amplification strategy. The sensitivity of amperometric immunosensor relies on the current response differences (ΔI) caused by per unit concentration target analyte. The pH responsive Cu2+-loaded polydopamine (CuPDA) particles conjugated with detection antibodies were employed as labels, which can release Cu(II) ions by regulating pH. In the presence of ascorbic acid (reductant), Cu(II) ions were reduced to Cu(I) ions. Azide-functionalized double-stranded DNA (dsDNA) as signal enhancer was immobilized on the substrate through Cu+-catalyzed azide/alkyne cycloaddition reaction. With the help of the click reaction, the ΔI caused by target was elevated prominently, resulting in sensitivity amplification of the immunosensor. Under optimal condition, the proposed immunosensor exhibited excellent performance with linear range from 0.0001 to 100 U mL−1 and ultralow detection limit of 20.74 μU mL−1. This work successfully combines click chemistry with pH-responsive labels in sandwich-type amperometric immunosensor, providing a promising sensitivity amplification strategy to construct immunosensing platform for analysis of other tumor marker. •Cu2+-polydopamine nanocomposites with antibody were used as smart labels.•pH responsive-label assisted click reaction was used to amplify sensitivity.•The immunosensor showed ultralow detection limit of 20.74 μU mL-1.
ISSN:0956-5663
1873-4235
DOI:10.1016/j.bios.2018.05.026