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Updated: May 18, 2026

Split Hybridization Probe Utilizing a DNA Fluorescent Light-up Aptamer as a Signal Reporter for Sequence-Specific Nucleic Acid Analysis
Published on: July 8, 2025
A colorimetric and fluorescent dual probe for specific detection of cysteine based on intramolecular nucleophilic
Limin Ma1, Junhong Qian, Haiyu Tian
1Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, 200237, PR China.
Abstract:
4-Nitro-1,8-naphthalic anhydride (NNA) was used to distinguish cysteine from homocysteine and other potentially interfering thiols through a novel sequential substitution mechanism. The discrimination involves a blue-fluorescent thioether formation via nucleophilic aromatic substitution of the nitro group by thiol, followed by a second intramolecular nucleophilic aromatic substitution of alkylthio with the amino group to give the green-fluorescent 4-amino derivative. NNA is highly selective towards Cys, and the detection limit of Cys by this method is 0.3 μM.
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