Open AccessRecyclable Target Metal-Enhanced Fluorometric Naked Eye Aptasensor for the Detection of Pb2+ and Ag+ Ions Based on the Structural Change of CaSnO3@PDANS-Constrained GC-Rich ssDNA
Author(s) -
Arunjegan Amalraj,
Rajaji Pavadai,
P. Panneerselvam
Publication year - 2021
Publication title -
acs omega
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.1c04319
Subject(s) - naked eye , fluorescence , stacking , chemistry , metal ions in aqueous solution , ion , metal , acridine orange , photochemistry , detection limit , crystallography , chromatography , organic chemistry , physics , apoptosis , biochemistry , quantum mechanics
Reliable, label-free, and ultraselective detection of Pb 2+ and Ag + ions is of paramount importance for toxicology assessment, human health, and environmental protection. Herein, we present a novel recyclable fluorometric aptasensor based on the Pb 2+ and Ag + -induced structural change of the GC-rich ssDNA (guanine cytosine-rich single-strand DNA) and the differences in the fluorescence emission of acridine orange (AO) from random coil to highly stable G-quadruplex for the detection of Pb 2+ and Ag + ions. More interestingly, the construction and principle of the aptasensor explore that the GC-rich ssDNA and AO can be strongly adsorbed on the CaSnO 3 @PDANS surface through the π-π stacking, hydrogen-bonding, and metal coordination interactions, which exhibit high fluorescence quenching and robust holding of the GC-rich ssDNA. However, in the presence of Pb 2+ , the specific G-rich ssDNA segment could form a stable G-quadruplex via G4-Pb 2+ coordination and capture of AO from the CaSnO 3 @PDANS surface resulting in fluorescence recovery (70% enhancement). The subsequent addition of Ag + ion induces coupled cytosine base pairs in another segment of ssDNA to get folded into a duplex structure together with the G-quadruplex, which highly stabilizes the G-quadruplex resulting in the maximum recovery of AO emission (99% enhancement). When the Cys@Fe 3 O 4 Nps are added to the above solution, the sensing probe was restored by complexation between the Cys in the Cys@Fe 3 O 4 Nps and target metal ions, resulting in the fabrication of a highly sensitive recyclable Pb 2+ and Ag + assay with detection limits of 0.4 and 0.1 nM, respectively. Remarkably, the Cys@Fe 3 O 4 Nps can also be reused after washing with EDTA. The utility of the proposed approach has great potential for detecting the Pb 2+ and Ag + ions in environmental samples with interfering contaminants.