Bimetallic complexes as cooperative partners in cell imaging and cancer therapy

Abstract

Fluorescence microscopy has become one of the more powerful tools in cell biology and related areas of bioscience. Their high sensitive detection that allows to visualize single molecules together with the possibility of monitoring rapidly changing events make this technique as the ideal tool to reveal key information about the mechanism of action of multiple metallodrugs. The idea of using fluorescence microscopy for visualizing biomaterial relays in the availability of having molecules with the suitable photophysical properties that can be used as light-bulbs inside the cells. Unfortunately, gold(I) and gold(III) metallodrugs lack sometimes of such capacity. Therefore, it is imperative to be able to design new species that bear together anticancer activity and emissive properties. A reasonable approach would be the development of bioactive luminescent heterometallic derivatives, being each metallic fragment the responsible of bringing together those features. Then a series of luminescent hometallic fac-[Re(bipy)(CO)3(L)]+ and heterometallic fac-[Re(bipy)(CO)3(L-AuPPh3)]+ complexes, where L is a functionalised ligand, have been synthesised for the purpose of finding a synergic effect between the excellent photophysical properties of rhenium complexes and the good antiproliferative effects of gold compounds. Re(I)/Au(I) derivatives presented values of IC50 more than 10 times lower than their analogous Re(I) complexes. In addition, fluorescent cell microscopy pointed out the different biodistribution behaviour of the homometallic and heterometallic families.