Methionine-derived Schiff base as selective fluorescent "turn-on" chemosensor for Zn2+ in aqueous medium and its application in living cells imaging

We describe the quantitative synthesis of a Schiff base derived from methionine and salicylaldehyde( SMSB) which displayed turn-on selective fluorescent chemo-sensing properties for Zn2+ in buffered CH3CN/H2O (1:1) solution. In physiological pH (7.2 buffered) SMSB exhibited high selectivity and sensitivity toward Zn2+ over the other selected metal ions. Upon the addition of Zn2+ 33 folds of emission enhancement was observed in SMSB and limit of detection (CL) for Zn2+ was found to be 5.0 x 10(-7) M. This binding phenomenon was studied by H-1 NMR and HR-MS analysis. Mass spectrometry analysis revealed that SMSB interacts with Zn2+ and form a 1:1 complex, also confirmed by Job's plot. This probe was completely retrieved by adding EDTANa(2) solution, exhibited a fluorescent quenching effect by removing Zn2+ from the sensor. SMSB was observed to have a good tolerance for fluorescence detection of Zn2+ in pH range 6-10. Furthermore it is successfully investigated for living cells imaging using MCF-7 cells. Combine experimental results indicated SMSB to be a useful and powerful chemosensing probe for Zn2+ in water as well as in living cells. (C) 2015 Elsevier B.V. All rights reserved.