The comparative study of two new Schiff bases derived from 5-(thiophene-2-yl)isoxazole as "Off-On-Off" fluorescence sensors for the sequential detection of Ga3+ and Fe3+ ions

Multi-bioapplicable fluorescence chemosensor for sequentially identifying gallium ion and pyrophosphate: Application to environmental samples, human serum, zebrafish and celery

A multi-bioapplicable fluorescence chemosensor MQV, ((E)-2-methoxy-6-((2-(quinolin-2-yl)hydrazineylidene)methyl)phenol), was developed for sequential detection of Ga3+ and pyrophosphate (PPi) ions. The addition of Ga3+ and PPi to MQV in sequence strongly caused an off-on-off fluorescent response in PBS buffer/DMSO (8:2, v/v, pH 7.4). The detection limits of MQV to Ga3+ and PPi were calculated as 3.00 μM and 4.49 μM, respectively. The 1:1 association mechanism of MQV to Ga3+ was determined using 1H NMR titration, Job plot and DFT calculations. The reliability of MQV for the practical detection of Ga3+ and PPi was demonstrated in real water samples like drinking, tap, river, seawater, and sewage. Notely, we affirmed the possibility for sequential detection of Ga3+ and PPi by MQV in biological systems such as human blood serum, living zebrafish, and fresh celery. In human serum, MQV signaled linearly in 0-125 μM toward Ga3+ and PPi under detection limits of 10.50 μM and 12.94 μM, respectively. Surprisingly, MQV is the first case to detect Ga3+via fluorescence change in plant and to sequentially detect Ga3+ and PPi in living zebrafish and plant.