A rapid and visual turn-off sensor for detecting copper (II) ion based on DNAzyme coupled with HCR-based HRP concatemers

Wentao Xu; Jingjing Tian; Yunbo Luo; Longjiao Zhu; Kunlun Huang

doi:10.1038/srep43362

A rapid and visual turn-off sensor for detecting copper (II) ion based on DNAzyme coupled with HCR-based HRP concatemers

Sci Rep. 2017 Mar 7:7:43362. doi: 10.1038/srep43362.

Authors

Wentao Xu^{1

2}, Jingjing Tian², Yunbo Luo¹, Longjiao Zhu², Kunlun Huang^{1

2}

Affiliations

¹ Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science &Nutritional Engineering, China Agricultural University, Beijing 100083, China.
² Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.

Abstract

To solve the requirement of on-site, rapid, and visual detection of copper (II) (Cu²⁺) in aqueous solution, a turn-off sensor for detecting copper (II) ion was developed based on Cu²⁺-dependent DNAzyme as the recognition element and hybridization chain reaction (HCR)-based horseradish peroxidase (HRP) concatemers as the signal amplifier and the signal report element. The detection unit, which was composed of the immobilized Cu²⁺-dependent DNAzyme coupled with HCR-based HRP concatemers via Waston-Crick base pairing, could catalyze hydrogen peroxide (H₂O₂) via TMB, generating obvious green color and turning yellow after sulfuric acid termination with optical absorption at 450 nm. Upon Cu²⁺ addition, the substrate strand of the Cu²⁺-dependent DNAzyme concatenated with the HCR-based HRP complex was irreversibly cleaved, efficiently causing dramatic reduction of the detection signal. Under optimal conditions, the detection signal decreased with the concentration of Cu²⁺ in 5 min, exhibiting a linear calibration from 0.05 to 3 μM with a detection limit of 8 nM. The sensor also displayed a high selectivity for Cu²⁺ given the specificity and anti-interference of the detection unit, and this system was applicable for monitoring Cu²⁺ in real water samples. Generally speaking, the proposed sensor exhibits good potential in environment surveys.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biosensing Techniques / methods*
Copper / analysis*
DNA, Catalytic / metabolism*
Horseradish Peroxidase / metabolism*
Nucleic Acid Hybridization*
Sensitivity and Specificity
Time Factors
Trace Elements / analysis*

Substances

DNA, Catalytic
Trace Elements
Copper
Horseradish Peroxidase