Thiazole orange as a fluorescent probe: Label-free and selective detection of silver ions based on the structural change of i-motif DNA at neutral pH.
Silver ions have been widely applied to many fields and have harmful effects on environments and human health. Herein, a label-free optical sensor for Ag(+) detection is constructed based on thiazole orange (TO) as a fluorescent probe for the recognition of i-motif DNA structure change at neutral pH. Ag(+) can fold a C-rich single stranded DNA sequence into i-motif DNA structure at neutral pH and that folding is reversible by chelation with cysteine (Cys). The DNA folding process can be indicated by the fluorescence change of TO, which is non-fluorescent in free molecule state and emits strong fluorescence after the incorporation with i-motif DNA. Thus, a rapid, sensitive, and selective method for the detection of Ag(+) and Cys is developed with a detection limit of 17 and 280nM, respectively. It is worth noting that the mechanism underlying the increase of the fluorescence of thiazole orange in the presence of i-motif structure is explained. Moreover, a fluorescent DNA logic gate is successfully designed based on the Ag(+)/Cys-mediated reversible fluorescence changes. The proposed detection strategy is label-free and economical. In addition, this system shows a great promise for i-motif/TO complex to analyze Ag(+) in the real samples.
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Bei Hua
BH
Kang
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Zhong Feng
ZF
Gao
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Na
N
Li
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Yan
Y
Shi
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. Electronic address: linb@swu.edu.cn.
Nian Bing
NB
Li
Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. Electronic address: luohq@swu.edu.cn.
Hong Qun
HQ
Luo
D052160:Benzothiazoles / Q000737:chemistry*; D015374:Biosensing Techniques / Q000191:economics / Q000379:methods*; D002414:Cations, Monovalent / Q000032:analysis; D003545:Cysteine / Q000032:analysis; D004277:DNA, Single-Stranded / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D009690:Nucleic Acid Conformation; D011804:Quinolines / Q000737:chemistry*; D012834:Silver / Q000032:analysis*; D013050:Spectrometry, Fluorescence / Q000191:economics / Q000379:methods; D014867:Water / Q000032:analysis
D052160:Benzothiazoles; D002414:Cations, Monovalent; D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D011804:Quinolines; D014867:Water; C051000:thiazole orange; D012834:Silver; D003545:Cysteine
Ag(+) detection; Fluorescence; Label-free; Thiazole orange; i-Motif