A novel pyrene based fluorescent probe for selective detection of cysteine in presence of other bio-thiols in living cells

This manuscript reports the synthesis of pyrene-based fluorescent probe (PA-1) containing a,(3-unsaturated carbonyl moiety and its application towards the selective and sensitive detection of cysteine (Cys) over other bio-thiols. The probe, 3-(32-hydroxyphenyl)-1-pyrenyl-2-propenone (PA-1) was synthesized through Claisen-Schmidt condensation between acetyl pyrene and salicylaldehyde. The formed product was characterized by H-1 NMR, C-13 NMR and GC-MS techniques. The probe exhibited absorption maximum at 374 nm and emission maximum at 467 nm (lambda(ex)=342 nm). The emission intensity of PA-1 was greatly enhanced while adding 2.5 nM Cys. This can be attributed to the nucleophilic attack of Cys to the alpha,beta-unsaturated ketone resulting in switching off, intramolecular charge transfer (ICT) from pyrene moiety to the phenolic nucleus. This was confirmed by DFT measurements. The PA-1 exhibited an excellent selectivity towards the determination of 40 nM cys in the presence of 250,000-fold higher concentration of common interferents. The emission intensity was linearly increased and the limit of detection was found to be 10 pM/L (S/N=3). Interestingly, the response of the PA-1 towards Cys is less than 1 min. The confocal laser scanning micrographs of HeLa cells confirmed the cell permeability of the PA-1 and its ability to selectively detect Cys in living cells. In addition, the proposed probe was successfully applied for the determination of Cys in blood serum samples. (C) 2016 Elsevier B.V. All rights reserved.