Ratiometric detection of Cu~+ in aqueous buffered solutions and in live cells using fluorescent peptidyl probe to mimic the binding site of the metalloprotein for Cu~+

摘要

Highlights•The fluorescent peptidyl probe for Cu(I) was easily synthesized in high yield (75%).•Highly sensitive and selective response to Cu(I) among various biological relevant metal ions.•Ratiometric response to Cu(I) and the intensity ratio (I472/I396) at 472 and 396nm increased by about 130 fold.•Cell penetration and ratiometric detection of intracellular Cu(I) in the Golgi apparatus in live cells.AbstractRatiometric detection of Cu+in aqueous buffered solutions and live cells is highly recomended. We synthesized a fluorescent probe (1)based on the peptide receptor to mimic the binding site of the metalloprotein (CusF) for Cu+.1sensitively and selectively detected Cu+among various biological relevant metal ions in aqueous solutions at physiological pH through a ratiometric response. Job’s plot analysis indicated that1formed a 2:1 complex with Cu+and the binding affinity of1for Cu+was measured to be 5.73×10−21M2from a competition experiment with bathocuproine disulfonate. The probe showed significant ratiometric responses to Cu+over a wide range of pH (6.5∼10.5). The binding mode study showed that the imidazole and indole groups of the peptide receptor played a critical role in the tight binding to Cu+.1penetrated successfully in living A549 cells and detected intracellular Cu+ions in Golgi apparatus through ratiometric response. Giving the recent growing interests in fluorescent imaging of Cu+, the development of a fluorescent ratiometric probe (1)based on the peptide receptor to mimic the binding site of the metalloprotein for Cu+will provide a potential tool for detection of intracellular metal ions in live cells.