A highly sensitive luminescent probe based on Ru(II)-bipyridine complex for Cu2+, l-Histidine detection and cellular imaging

A ruthenium(II) bipyridyl complex conjugated with functionalized Schiff base (RuA) has been synthesized and functioned as a luminescent probe. The luminescence of RuA was greatly quenched by Cu 2+ due to its molecular coordination with paramagnetic Cu 2+ . Subsequently, the addition of l -Histidine can turn on the luminescence of the RuA-Cu(II) ensemble, which can be attributed to the replacement of RuA in RuA-Cu(II) ensemble by l -Histidine. On the basis of the quenching and recovery of the luminescence of RuA, we proposed a rapid and highly sensitive on-off-on luminescent assay for sensing Cu 2+ and l -Histidine in aqueous solution. Under the optimal conditions, Cu 2+ and l -Histidine can be detected in the concentration range of 5 nM–9.0 μM and 50 nM–30 μM, respectively, and the corresponding detection limits were calculated to be 0.35 and 0.44 nM (S/N=3), separately. The proposed luminescent probe has been successfully utilized for the analysis of Cu 2+ and l -Histidine in real samples (drinking water and biological fluids). Furthermore, the probe revealed good photostability, low cytotoxicity and excellent permeability, making it a suitable candidate for cell imaging and labeling in vitro.