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

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??M 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.

SUBMITTER: Xu W 

PROVIDER: S-EPMC5339725 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature