A switch-on near-infrared fluorescence-ready probe for Cu(I): live cell imaging

A reaction-based strategy exploiting metal ion mediated oxidative C–O bond cleavage affords selective ‘switch-on’ near-infrared (NIR) emitting cyanine probe for Cu+ in aqueous media and live cells. Near-infrared fluorescence-ready probe TPACy readily reacts with Cu+ to release the quinone embedded heptamethine cyanine (Cy-quinone) with extended π-electron conjugation responsible for the switch-on NIR fluorescence in aqueous buffer solution (50 mM HEPES, pH 7.2). This probe can be conveniently used for monitoring Cu+ without the interference from pH dependent effects of physiological media. Utility of the probe has been demonstrated by its application in the detection of unbound copper species (Cu+) in live cells.