A new electrochemical immunoassay for prion protein based on hybridization chain reaction with hemin/G-quadruplex DNAzyme

Publication date: 15 May 2018
Source:Talanta, Volume 182
Author(s): Xiaoyu Li, Junjing Li, Caixia Zhu, Xiaohua Zhang, Jinhua Chen
In this work, a new electrochemical immunosensor was developed for prion protein assay based on hybridization chain reaction (HCR) with hemin/G-quadruplex DNAzyme for signal amplification. In this amplification system, the hemin/G-quadruplex DNAzyme simultaneously mimicked the biocatalytic functions for H2O2 reduction and L-cysteine oxidation. In the presence of L-cysteine, the hemin/G-quadruplex catalyzed the oxidation of L-cysteine to L-cystine. At the same time, H2O2 was produced under the oxygen condition. Then, the hemin/G-quadruplex could quickly catalyze the reduction of H2O2, mimicking the catalytic performance of horseradish peroxidase (HRP). Under the optimal conditions, the immunosensor showed a wide linear response range from 0.5 pg/mL to 100 ng/mL with the low detection limit of 0.38 pg/mL (3σ). By changing the specific antibody, this strategy could be easily extended to detect the infectious isoform of prion (PrP^Sc) and other proteins. Based on its good analytical performance, the developed method shows great potential applications in diagnosis of prion diseases at presymptomatic stage and bioanalysis.

Graphical abstract

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