Quercetin mediated gold nanoclusters explored as a dual functional nanomaterial in anticancer and bio-imaging disciplines.

Quercetin-mediated gold nanoclusters (Qu-GNCs) were prepared for the first time by employing bovine serum albumin (BSA) as a stabilizer with a natural flavonoid, "quercetin" as a reducing agent. Interestingly, quercetin (Qu) forms a cluster by reacting with gold under alkali conditions in the presence of BSA. Transmission electron microscopy (TEM) images of obtained nanoclusters exhibit the optimal size with homogenous distribution. Similarly, Fourier transform infrared spectroscopy (FTIR) confirmed the conjugation between Qu and GNCs and the photoluminescence (PL) spectra showed the bright yellowish-orange fluorescence of Qu-GNCs and they are stable over a long period of time. Further, Bio-atomic force microscopy (Bio-AFM) and confocal imaging of A549 (lung cancer cell lines) highlighted the cell morphology and cluster's efficacy, respectively. Moreover, as-synthesized Qu-GNCs exerted high and minimal toxicities on A549 and HDFa (fibroblast cells). The obtained results are very interesting and have shown that Qu-GNCs are promising anti-cancer agents as well as potential bio-imaging nanohybrids.