A label-free turn-on-off fluorescent sensor for the sensitive detection of cysteine via blocking the Ag+-enhancing glutathione-capped gold nanoclusters

Li, Ye; Deng, Yi; Zhou, Xiaodong; Hu, Jiming

doi:10.1016/j.talanta.2017.11.057

Cited by 39 publications

(9 citation statements)

References 53 publications

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“…After the addition of Ag + , the signal input mode as (1, 0), the random coil sequence is switched to a compact i-motif conformation of C−Ag + −C mismatch through N3−Ag + −N3 linear coordination, 35 which provides a more rigid microenvironment for berberine and limits its rotation by the interaction of berberine with i-motif DNA, resulting in a great change of fluorescence intensity, anisotropy, and lifetime. After cysteine is introduced, the signal input mode as (1, 1), the i-motif conformation of C−Ag + −C would be disintegrated based on the stronger coordination of Ag + and cysteine, 36 resulting in the recovery of the tripleoutput results. On this basis, a highly sensitive sensing tripleoutput molecular logic gate for Ag + and cysteine can be obtained.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Versatile Triple-Output Molecular Logic Gate for Cysteine and Silver (I) in Foods and the Environment Based on I-Motif DNA Modulation

Wei

Wang

et al. 2022

J. Agric. Food Chem.

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DNA-based molecular logic gates have been developed rapidly but most of them have a single output mode. This study is to develop a triple-output label-free fluorescent DNA-based multifunctional molecular logic gate with berberine as a fluorescent signal and a Ag+–aptamer as a recognition matrix. The Ag+–aptamer has been identified to switch from a random coil to an i-motif structure of C–Ag+–C from a Ag+-induced responsive conformational change. As a fluorescent probe, berberine is ultrasensitive to the changes of microenvironments, and the binding to i-motif DNA’s more rigid structure causes a significant increase in fluorescence, anisotropy, and lifetime. The addition of cysteine to the berberine/C–Ag+–C system disintegrates the i-motif DNA structure because of the strong coordination between Ag+ and cysteine, and then the triple-output signals are almost retrieved. Given this, a highly sensitive triple-output molecular logic gate for the analyses of Ag+ and cysteine is constructed with high specificity. Moreover, this simple and cost-effective molecular logic gate has been applied for the detection of cysteine and Ag+ in various real environmental samples including river water, PM2.5, soil, and food samples with satisfactory recoveries from 89.83 to 106.04%.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Versatile Triple-Output Molecular Logic Gate for Cysteine and Silver (I) in Foods and the Environment Based on I-Motif DNA Modulation

Wei

Wang

et al. 2022

J. Agric. Food Chem.

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“…The XPS peak fitting analysis results indicated that the silver in Ag-AuNCs consisted of approximately 28.2% Ag 0 and 71.8% Ag + , which implied that after the addition of Ag + to AuNCs most of the Ag + ions combined with the carboxylate groups on AuNCs shell and some Ag + ions interacted with the AuNCs core and got reduced to Ag 0 by the thiol group of glutathione (demonstrated in Figure S2). Then, a displacement reaction could take place between the reduced Ag 0 and Au + to generate Ag + and Au 0 , which was the reason for the Au + decrease of Ag-AuNCs after Ag + modification. Based on the above findings, the Ag-induced fluorescence enhancement of AuNCs mechanism was mainly due to the Ag 0 which existed on the AuNCs core structure and a part Ag + anchored on the AuNCs shell to remove the surface defects and affect the luminescent features of AuNCs. , Besides, the XPS results of Au 0 increase and Au + decrease in AuNCs after Ag + introduction implied that the decrease of Au 1 in the Au 1 –thiolate complex shell structure and increase of the Au 0 atoms in the Au 0 core, which indicated the Ag + doping affected the structure of AuNCs and further explained for the emission spectra shift changes of AuNCs in Figure A.…”

Section: Resultsmentioning

confidence: 99%

Ag-Ion-Modified Au Nanoclusters for Fluorometric Analysis of Alkaline Phosphatase

Wang

Xie

et al. 2020

ACS Appl. Nano Mater.

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Alkaline phosphatase (ALP) has been regarded as one vital biomarker in clinical diagnoses and biomedical studies, and fabrication of sensitive and effective approaches for ALP analysis is of extraordinary significance. Herein, a ratio fluorometric platform was constructed for ultrasensitive detection of ALP utilizing silver ion (Ag+)-modified gold nanoclusters (Ag-AuNCs) and o-phenylenediamine (OPD) as signal indicators. The AuNCs fluorescence was greatly enhanced via simply modifying with Ag+. With the addition of ALP, the substrate ascorbic acid 2-phosphate (AAP) was transformed to ascorbic acid (AA). Then, a redox reaction between KIO3 and AA was employed to produce I2/I– and dehydroascorbic acid (DHA). The I2/I– caused the notable fluorescence quenching of Ag-AuNCs at 600 nm through I– combining with Ag+ and I2 triggered oxidative etching and aggregation of Ag-AuNCs. Meanwhile, DHA reacted with OPD to form a fluorescent quinoxaline derivative (QXD) with apparent emission at 438 nm. Therefore, by measuring the fluorescence intensity ratio (F 438/F 600) of this fluorometric platform, we sensitively monitored the ALP activity with a low detection limit of 0.0035 U L–1. Moreover, the practical application was demonstrated by ALP analysis in human serum with high accuracy and reliability, which endowed this platform as a competitive alternative for ALP-related diagnostic analysis.

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“…In terms of surface ligands, AuNCs are generally classified into thiolated AuNCs, dendrimer- or polymer-protected AuNCs, protein-templated or protein-protected AuNCs, DNA-templated AuNCs, and small-molecule-protected AuNCs [ 13 ]. Among various AuNCs, glutathione (GSH)-stabilized AuNCs (GSH-AuNCs) have been demonstrated to have many interesting properties and have been used in the detection of heavy metal ions such as Cr 3+ [ 14 ], Cu 2+ [ 15 ], Hg 2+ [ 16 , 17 , 18 ], and Ag + [ 19 , 20 ]; thiol [ 21 , 22 ]; and alkaline peptide and alkaline phosphatase [ 23 , 24 ]. GSH-AuNCs have also been applied to detect the electron deficiency of dopamine [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

A Fluorescent Detection for Paraquat Based on β-CDs-Enhanced Fluorescent Gold Nanoclusters

Ren

Mao

et al. 2021

Foods

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In this report, a fluorescent sensing method for paraquat based on gold nanoclusters (AuNCs) is proposed. It was found that paraquat could quench both glutathione-capped AuNCs (GSH-AuNCs) and β-cyclodextrin-modified GSH-AuNCs (GSH/β-CDs-AuNCs). The modification of β-CDs on the surface of GSH-AuNCs obviously enhanced the fluorescence intensity of GSH-AuNCs and improved the sensitivity of paraquat sensing more than 4-fold. This sensibilization was ascribed to the obvious fluorescence intensity enhancement of GSH-AuNCs by β-CDs and the “host–guest” interaction between paraquat and β-CDs. The fluorescence quenching was mainly due to the photoinduced energy transfer (PET) between GSH/β-CDs-AuNCs and paraquat. With the optimized β-CDs modification of the GSH-AuNC surfaces and under buffer conditions, the fluorescent detection for paraquat demonstrated a linear response in the range of 5.0–350 ng/mL with a detection limit of 1.2 ng/mL. The fluorescent method also showed high selectivity toward common pesticides. The interference from metal ions could be easily masked by ethylene diamine tetraacetic acid (EDTA). This method was applied to the measurement of paraquat-spiked water samples and good recoveries (93.6–103.8%) were obtained. The above results indicate that host molecule modification of fluorescent metal NC surfaces has high potential in the development of robust fluorescent sensors.

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A label-free turn-on-off fluorescent sensor for the sensitive detection of cysteine via blocking the Ag+-enhancing glutathione-capped gold nanoclusters

Cited by 39 publications

References 53 publications

Versatile Triple-Output Molecular Logic Gate for Cysteine and Silver (I) in Foods and the Environment Based on I-Motif DNA Modulation

Versatile Triple-Output Molecular Logic Gate for Cysteine and Silver (I) in Foods and the Environment Based on I-Motif DNA Modulation

Ag-Ion-Modified Au Nanoclusters for Fluorometric Analysis of Alkaline Phosphatase

A Fluorescent Detection for Paraquat Based on β-CDs-Enhanced Fluorescent Gold Nanoclusters

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