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Complete suppression of the fluorophore fluorescence by combined effect of multiple fluorescence quenching groups: A fluorescent sensor for Cu2+ with zero background signals

Long, Lingliang, Wu, Yanjun, Wang, Lin, Gong, Aihua, Hu, Rongfeng, Zhang, Chi
Analytica chimica acta 2016 v.908 pp. 1-7
analytical chemistry, copper, coumarin, detection limit, fluorescence, fluorescent dyes
The reaction-based fluorescent sensors have attracted increasing attention in the past decades. However, the application of these sensors for accurate sensing was significantly retarded by the background fluorescence from the sensors themselves. In this work, we demonstrated a novel strategy that the background fluorescence of the sensor could be completely eliminated by the combined effect of multiple fluorescence quenching groups. Based on this new strategy, as proof-of-principle study, a fluorescent sensor (CuFS) for Cu2+ was judiciously developed. In CuFS, three types of fluorescence quenching groups were directly tethered to a commonly used coumarin fluorophore. The fluorescence of coumarin fluorophore in CuFS was completely suppressed by the combined effect of these fluorescence quenching groups. Upon treatment with 22 μM Cu2+, sensor CuFS achieved a dramatic fluorescence enhancement (fluorescence intensity enhanced up to 811-fold) centered at 469 nm. The detection limits was determined to be 12.3 nM. The fluorescence intensity enhancement also showed a good linearity with the Cu2+ concentration in the range of 12.3 nM to 2 μM. By fabricating test strips, sensor CuFS can be utilized as a simple tool to detect Cu2+ in water samples. Furthermore, the fluorescent sensor was successfully applied in detecting different concentration of Cu2+ in living cells.