The rational development of a versatile tool capable of rapid and cyclic detection of nerve agents is of great significance due to their extreme toxicity. Herein, we report a reversible colorimetric and ratiometric fluorescent probe ( DMC-Py ) for rapid and cyclic detection of nerve agent mimic (diethyl chlorophosphate, DCP) base on intramolecular charge transfer (ICT) mechanism. When exposed to DCP, the pyridine unit of DMC-Py is quickly converted to pyridinium salt (<7 s); meanwhile, the toxic DCP is simultaneously transformed into non-toxic neutral phosphate ester, accompanying by a rapid color change from light green to dark yellow, and fluorescence change from cyan to orange red because of the enhancement of the ICT effect. The probe exhibits high sensitivity and specificity in solution. For DCP vapour detection, the filter paper shows a distinct color transition, precisely quantifiable via a smartphone application. A linear correlation between the R/G ratio and 0 – 10.24 ppm DCP has been established, vividly illustrating its potential for field applications. The addition of triethylamine to the corresponding DMC-PyH product can regenerate the original DMC-Py . Alternate exposure of DMC-Py to DCP and triethylamine can induce the color and dual-emission changes in both solution phase and filter paper, thereby achieving the reversibility of the probe. This strategy provides a critical framework for rationally designing reversible ratiometric fluorescent probes for cyclic detection of nerve agents.
A self-cleaning electrochemical biosensor based on two-dimensional Cu-porphyrin (Cu-TCPP) metal-organic framework nanofilms , novel super G-quadruplex (G4), and DNA nanomotors was developed for the cyclic detection of Pb 2+ ions. The Cu-TCPP framework with inherent peroxidase activity can create an ultra-thin nanofilm that functioned as a carrier to support the metastable G4 comprising four individual DNA strands. The introduction of Pb 2+ and the intercalation of hemin can help it to form stable G4-hemin DNAzymes, which exhibits strong catalytic H 2 O 2 reduction activity, and its number will be directly related to the amount of the introduced Pb 2+ . Moreover, a DNA nanomotor system is introduced to achieve cyclic detection, and the addition of the fuel DNA strands enables G4 to perform a “complete-dissociation-complete” process for achieving self-cleaning of the electrode interface and the cycle detection of Pb 2+ . The synergistic effects of Cu-TCPP and G4-hemin DNAzymes, which exhibits efficient and catalytic H 2 O 2 reduction, enhance the performance of the electrochemical sensing system. The linear range of this sensor to Pb 2+ is 5 nM–5 μM, and the detection limit is 1.7 nM. Compared with the best system in reported studies, its linear range is five times wider and its detection limit is lower than the previously lowest one. Taking advantage of the Pb 2+ stabilized G4, the proposed sensor can selectively detect Pb 2+ in the presence of other metal ions . The results presented herein comprise a valuable reference for constructing DNA nanoelectronic devices and establish sensitive and cyclic detection of the target and preparing of self-cleaning electrode interfaces.
危险品化学品经营许可证（带存储）