Ultrasensitive colorimetric strategy for Hg2+ detection based on T-Hg2+-T configuration and target recycling amplification

Fuming Sang; Suyao Yin; Jianxin Pan; Zhizhou Zhang

doi:10.1007/s00216-021-03657-1

Ultrasensitive colorimetric strategy for Hg²⁺ detection based on T-Hg²⁺-T configuration and target recycling amplification

Anal Bioanal Chem. 2021 Nov;413(28):7001-7007. doi: 10.1007/s00216-021-03657-1. Epub 2021 Sep 16.

Authors

Fuming Sang¹, Suyao Yin², Jianxin Pan², Zhizhou Zhang²

Affiliations

¹ School of Marine Science and Technology, Harbin Institute of Technology, Weihai, 264209, People's Republic of China. sangfuming@hitwh.edu.cn.
² School of Marine Science and Technology, Harbin Institute of Technology, Weihai, 264209, People's Republic of China.

PMID: 34532763
DOI: 10.1007/s00216-021-03657-1

Abstract

A novelty aptasensor for ultrasensitive detection of Hg²⁺ is developed, exploiting the combination of plasmonic properties of gold nanoparticles (AuNPs) and exonuclease III (Exo III)-assisted target recycling for signal amplification. In the presence of Hg²⁺, a DNA duplex can be formed due to the strong coordination of Hg²⁺ and T bases of single-stranded DNA (ssDNA) probe. Exo III digests the DNA duplex from the 3' to 5' direction, resulting in the releasing of Hg²⁺. Then, the released Hg²⁺ binds with another ssDNA probe through T-Hg²⁺-T coordination. After Exo III-assisted Hg²⁺ cycles, numerous ssDNA probes are exhausted, which promotes poly(diallyldimethylammonium chloride) (PDDA)-induced AuNP aggregation, leading to an obvious color change and aggregation-induced plasmon red shift of AuNPs (from 520 to 610 nm). Therefore, this biosensor is ultrasensitive, which is applicable to the detection of trace level of Hg²⁺ with a linear range from 5 pM to 0.6 nM and an ultralow detection limit of 0.2 pM. Furthermore, it enables visual detection of Hg²⁺ as low as 50 pM by the naked eye. More importantly, the assay can be applied to the reliable determination of spiked Hg²⁺ in sea water samples with good recovery.

Keywords: Aptamer; Colorimetry; Exonuclease III; Mercury(II).