Fluorescence lifetime sensors for copper(II) ions based on resonance energy transfer

Two kinds of fluorescence lifetime sensors for copper(II) ions based on energy transfer are presented in this study. The previously developed [I] sensor with near infra-red donor Rhodamine 800 and Cu(II) ion as acceptor is compared with a new system based on Texas Red X as the donor and N,N,N',N'-tetra-methylethylene diamine : Cu(II) complex as acceptor. Enhanced absorption spectra of the ligand:Cu(II) complex increases the rate of energy transfer what improves detection limit for copper concentration in water down to similar to 2 ppb.