Oestradiol post-functionalized gold( <scp>i</scp> ) bis(1,2,3-triazol-5-ylidene) complex exhibits high activity for ERα-positive breast cancer cells (MCF-7)

Au(I) N-heterocyclic carbene (NHC) complexes have shown promising cytotoxicity against cancer cells, yet improving their selectivity remains a key challenge. In this study, a modular strategy to enhance tumor targeting by post-functionalizing an Au(I) bis-aNHC_trz complex (trz = 1,2,3-triazole-5-ylidene) with oestradiol <i>via</i> copper-catalyzed click chemistry is introduced. The resulting conjugate shows high cytotoxicity in the nanomolar range and markedly increased accumulation in ERα-positive breast cancer cells compared to its non-functionalized analogue. This work demonstrates the potential of hormone-based vectors to guide gold complexes selectively to hormone receptor-positive cancer cells.