Nanoclusters prepared from ruthenium(II) and quercetin for fluorometric detection of cobalt(II), and a method for screening their anticancer drug activity.

Abstract

Ruthenium-quercetin conjugated nanoclusters (Ru-QC NCs) were synthesized via a one-pot reflux reaction. As inhalation of heavy metal ions like cobalt can lead to lung cancer, a fluorescent probe was designed for the determination of Co(II) both in aqueous solutions and living cells. The probe consists of hybrid nanoclusters with an average size of 2nm that were prepared from ruthenium(II) ions and the flavonoid quercetin. These are termed as Ru-QC NCs. They display strong orange-colored emission with a peak at 558nm under 465-nm excitation. The Ru-QC NCs are cell viable and enable imaging of cells and intracellular fluorometric detection of Co(II). The anticancer properties of Ru-QC NCs were screened by using non-small cell lung cancer (A549) and human dermal fibroblast (HDFa) cell lines. The Ru-QC NCs exert considerable cytotoxicity in A549 cells (at levels of 20-50μg·mL-1), whereas no significant cytotoxicity was observed in case of HDFa cells. The anticancer properties of Ru-QC NCs were screened via MTT assay, live-dead staining, and ROS assay, respectively. Morphological changes of cancer cells were observed using atomic force microscopy. The fluorescent probe can detect Co(II) with a detection limit of 9.28nM and with a linear response in the 0.03-100μM concentration range. Graphical abstract Schematic representation of ruthenium-quercetin nanoclusters with potential anticancer properties. They are promising fluorescent probes for intracellular sensing of cobalt (Co2+) and bio-imaging. They exhibited efficient fluorometric detection of Co2+ with the limit of detection (LOD) of 9.28nM.