A Fluorescence Resonance Energy Transfer Probe Based on DNA-Modified Upconversion and Gold Nanoparticles for Detection of Lead Ions.

Yue Wang,Zilong Deng,Zehan Chen,Menghua Lv,Weixian Zhang,Ningtao Liu,Jianwei Fan

doi:10.3389/fchem.2020.00238

Abstract

We report a new sensor for the specific detection of lead ions (Pb2+) in contaminated water based on fluorescence resonance energy transfer (FRET) between upconversion nanoparticles (UCNPs) as donors and gold nanoparticles (Au NPs) as receptors. The UCNPs modified with Pb2+ aptamers could bind to Au NPs, which were functionalized with complementary DNA through hybridization. The green fluorescence of UCNPs was quenched to a maximum rate of 80% due to the close proximity between the energy donor and the acceptor. In the presence of Pb2+, the FRET process was broken because Pb2+ induced the formation of G-quadruplexes from aptamers, resulting in unwound DNA duplexes and separated acceptors from donors. The fluorescence of UCNPs was restored, and the relative intensity had a significant linear correlation with Pb2+ concentration from 0 to 50 nM. The sensor had a detection limit as low as 4.1 nM in a buffer solution. More importantly, the sensor exhibited specific detection of Pb2+ in complex metal ions, demonstrating high selectivity in practical application. The developed FRET prober may open up a new insight into the specific detection of environmental pollution.

Highlights

Lead ion (Pb2+), one of the most serious metallic toxicants, can damage cardiovascular, reproductive, neurological, and developmental systems of the human body at low concentrations in the blood (Yoosaf et al, 2007; Zhou et al, 2011; Kim et al, 2012; Li et al, 2013)
The sensor for Pb2+ detection was based on fluorescence resonance energy transfer (FRET) from modified upconversion nanoparticles (UCNPs) to Au NPs by an aptamer matching its complement (Figure 1)
The FRET system was established with UCNPs as donors and Au NPS as receptors

Summary

Introduction

Lead ion (Pb2+), one of the most serious metallic toxicants, can damage cardiovascular, reproductive, neurological, and developmental systems of the human body at low concentrations in the blood (Yoosaf et al, 2007; Zhou et al, 2011; Kim et al, 2012; Li et al, 2013). The detection assay composed of fluorescence and DNA molecules has attracted more and more attention mainly due to sensitive fluorescence signal, stable DNA molecules, and highly specific binding ability between specific sequences and target detectors (e.g., protein, ions, virus, and nucleic acid aptamers) (Hamaguchi et al, 2001; Pavlov et al, 2004; Xiao et al, 2005; Chang et al, 2010; Saha et al, 2012). Zhou and co-workers labeled 6-carboxyfluorescein on G-rich DNA strands and monitored the reduction of fluorescence for Pb2+ detection (Zhan et al, 2013). Shi and co-workers developed a new strategy based on DNA-templated silver nanoclusters with elevated fluorescence for L-histidine detection (Zheng et al, 2015). The “turn-off–on” detection system based on fluorescence resonance energy transfer (FRET) is introduced to avoid external interferences

Methods

Results

Conclusion