Multi-talented applications for cell imaging, tumor cells recognition, patterning, staining and temperature sensing by using egg white-encapsulated gold nanoclusters

We herein provide a facile and green strategy for the fabrication of red fluorescence gold nanoclusters (AuNCs@ew) with low toxicity, good stability and excellent fluorescence (lambda(em) =650nm, lambda(ex)= 320 nm) by mixing aqueous tetrachloroauric acid with diluted egg white under alkaline environment using microwave-assisted method. Confocal fluorescence imaging showed that the AuNCs@ew can enter living cells and distribute in the cytoplasm. In addition, the fluorescence of AuNCs@ew is sensitive to the response of Cu2+ and Hg2+ with a detection limit of 14.48 nM and 0.81 nM, respectively. Interestingly, we found that the fluorescent signal of the quenched AuNCs@ew-Hg(II) system could be recovered in the presence of the glutathione (GSH) in Tris-HCI medium (pH 6.5). This assay displayed a rapid response and highly selectivity toward GSH with a detection limit of 91.9 nM. More excitingly, the fluorescent signal of the AuNCs@ew-Hg(II) system (OFF) could be activated in living tumor cells (ON) such as HepG2 cells rather than in living normal cells (HT22 cells, OFF) without any exogenous GSH. The result showed that the system can be successfully applied for tumor cells recognition, which implied its great potential application in early prevention of cancer. Furthermore, the AuNCs@ew can also be used for patterning, staining and temperature sensing. We propose that the highly fluorescent AuNCs@ew can be eco-friendly and potentially large-scale development for versatile applications and so merits further study. (C) 2016 Elsevier B.V. All rights reserved.