A new platinum(II) complex for bioimaging applications

Two platinum(II) complexes containing imidazolyl terpyridine (1) and benzimidazolyl terpyridine (2) were synthesized and characterized by ESI-MS, 1H NMR, UV-Visible and fluorescence spectroscopy. Pt(II) complex 1 emits weakly in an aqueous solution but not complex 2. On addition of DNA, a 21-fold increase in the emission intensity of complex 1 was observed. Both complexes did not exhibit any change in emission maxima with serum albumin. No uptake of the complexes by live cells was observed. In dead cells, complex 1 stains the nuclear DNA specifically without addition of any external fluorophore. The apoptotic pathway of the cells induced by plumbagin was monitored using complex 1. Application of complex 1 as a DNA staining dye was tested in agarose gel electrophoresis. Taken together, the results from this study presents a new platinum(II) complex as a DNA staining agent, an alternative to highly mutagenic ethidium bromide in gel electrophoresis as well as in dead cells at a non-toxic concentration.