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 ( [email protected] ) with low toxicity, good stability and excellent fluorescence (λ em   =   650   nm, λ 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 [email protected] can enter living cells and distribute in the cytoplasm. In addition, the fluorescence of [email protected] is sensitive to the response of Cu 2+ and Hg 2+ with a detection limit of 14.48   nM and 0.81   nM, respectively. Interestingly, we found that the fluorescent signal of the quenched [email protected] (II) system could be recovered in the presence of the glutathione (GSH) in Tris-HCl 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 [email protected] (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 [email protected] can also be used for patterning, staining and temperature sensing. We propose that the highly fluorescent [email protected] can be eco-friendly and potentially large-scale development for versatile applications and so merits further study.