A water compatible turn ‘on’ optical probe for Cu2+ based on a fluorescein-sugar conjugate

Published in: Journal, Volume : 196, Pages : 345-351

DOI : 10.1016/j.snb.2014.02.031

Author : Diwan, Uzra; Kumar, Ajit; Kumar, Virendra; Upadhyay, K. K.; Roychowdhury, P. K.

Abstract : A fluorescein-sugar conjugated chromo-fluorogenic turn ‘on’ probe (FG) has been synthesized for detection of Cu2+. The FG comprises of fluorescein as an efficient fluorophore and a sugar moiety, viz., galactose as the binding unit. The inclusion of galactose into FG led towards its good water compatibility. When Cu2+ was added in 70% aqueous HEPES buffered solution (pH 7.4) of FG, the absorbance and the fluorescence spectral pattern of the same were modulated dramatically with observation of absorption and emission bands at 632 and 515 nm, resp. The detection limit from fluorescence titration was calculated as 6.32 nM which further establishes high sensitivity of FG towards Cu2+. The spectral studies for the interaction of FG with Cu2+ indicated towards metal ion triggered spirolactam ring opening of FG as the mechanistic pathway of the sensing phenomenon.