We have developed two highly sensitive cyanine dyes, which we refer to as probes A and B. These dyes are capable of quick and sensitive sensing of NAD(P)H. The dyes were fabricated by connecting benzothiazolium and 2,3dimethylnaphtho[1,2-d]thiazol-3-ium units to 3-quinolinium through a vinyl bond. In the absence of NAD(P)H, both probes have low fluorescence and absorption peaks at 370 and 400 nm, correspondingly. This is because of their two electron-withdrawing acceptor systems with high charge densities. However, when NAD(P)H reduces the probes' electron-withdrawing 3-quinolinium units to electron-donating 1,4-dihydroquinoline units, the probes absorb at 533 and 535 nm and fluoresce at 572 and 586 nm for A and B correspondingly. This creates well-defined donor−π− acceptor cyanine dyes. We successfully used probe A to monitor NAD(P)H levels in live cells during glycolysis, under hypoxic conditions induced by CoCl 2 treatment and after treatment with cancer drugs, including cisplatin, camptothecin, and gemcitabine. Probe A was also employed to visualize NAD(P)H in Drosophila melanogaster first-instar larvae. We observed an increase in NAD(P) H levels in A549 cancer cells both under hypoxic conditions and after treatment with cancer drugs, including cisplatin, camptothecin, and gemcitabine.
A fluorescent probe based on dicyanovinylphenanthroimidazole (DCPPI) has been designed and synthesized and its potential application to recognize Fand CNions via different channels has been tested in different medium. DCPPI shows intramolecular charge transfer process and exhibit ratiometric response toward Fand CNions. The change in physicochemical properties of DCPPI in the presence of cyanide can be attributed to the formation of Michael type adduct, DCPPIA whereas both Fand CNions have shown affinities to interact with NH fragment of imidazolyl unit under the condition. The possible mode of interaction has been confirmed by absorption, emission, NMR and ESI-MS spectral data analysis.
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