• anticancer gold(I) complexes
• biodistribution studies
• fluorescent gold(I) complexes

In recent years gold-based complexes have attracted increasing interest as promising and alternative antitumor agents. This interest stems from the different mechanism of action, with respect to the classical Pt-based drugs, mainly exerted at the mitochondrial level. However, a more in-depth understanding of those mechanisms and the overall biological behavior of gold complexes is necessary for designing more effective antitumor complexes. Therefore, a panel of mono and bis N-heterocyclic carbene gold(I) complexes endowed with fluorescent labels was synthesized to exploit their luminescence properties in cellular uptake and biodistribution studies using confocal microscopy and target protein identification through electrophoresis. Two biocompatible fluorescent probes: the anthracenyl moiety and BODIPY were chosen for their different luminescence properties. The synthesized compounds were characterized through 1H, 13C NMR and elemental analysis. Moreover, the complexes remained stable in DMSO at least for 48 h at 25 °C but were unstable in PBS buffer under the same conditions. Studies conducted through UV-Vis absorption spectroscopy did not show significant signs of interaction with HSA, except for the monocarbene with the BODIPY probe. Cellular uptake studies using FACS cytofluorimetry highlighted strong cellular uptake of all compounds, particularly the biscarbene labelled with the anthracenyl moiety. The cytotoxicity of the complexes was assessed on A2780 ovarian cancer cells. Both monocarbenes showed high IC50 values, especially the one with BODIPY, while the biscarbene with anthracene substituent exhibited a lower IC50 than cisplatin.