An On-off Supramolecular Fluorescence Switch for Detection of Pb2+ Ions and Vitamin C.

ß-cyclodextrin-hydroxyquinoline functionalized graphene oxide (GO-CD-HQ) was facilely fabricated to monitor and quantitatively analyze cations in aqueous media. The optical probe was notably selective enhanced toward Pb2+ ions over the other tested ions like Cu2+, Hg2+, Ca2+, Na+, K+, Zn2+, Fe2+, Fe3+, Ag+, Mg2+, and Cd2+ at 468 nm as an emission wavelength. The probe was shown the best performance in pH value, 5, and optimum time 1 min. Absorption spectra have clearly confirmed the static type fluorescence enhancement mechanism of GO-CD-HQ. Under the optimal conditions, the detection limit of it and linear concentration range for Pb2+ ions were obtained as 3.72 × 10-5 M and (5-60) × 10-5 M, respectively. Additionally, the developed assay exhibited logic gate behavior with Pb2+ ions and vitamin C as a masking agent for cited ions.

Fluorescence turn off-on probe (ß-cyclodextrin-hydroxyquinoline) for monitoring of Cd2+ ions and tetracycline.

In this paper, a photoluminescent turn off-on switch probe ß-cyclodextrin-hydroxyquinoline (ß-CD-HQ) was efficiently applied for detection and measurement of Cd2+ ions and detection of tetracycline. The proposed assay has shown an excellent selective fluorescence response toward Cd2+ ions over other ions like Al3+, Pb2+, Zn2+, Co2+, K+, Na+ and Sr2+. The fluorescence emission intensity of the probe is slightly affected by competing ions. In optimum pH value, 4, the limit of detection and linear concentration range were 0.05 nM and 0.1-1.5 nM, respectively. Additionally, the extraordinary output signal of ß-CD-HQ was utilized to investigate the logic behavior of ß-CD-HQ in the aqueous media. Accordingly, a solid support logic circuit was made by producing the fluorescence output signal under the stimulation of Cd2+ ions and tetracycline as inputs.