Glutathione capped gold nanoclusters-based fluorescence probe for highly sensitive and selective detection of transferrin in serum

In this study, we developed a novel approach for the first time to detect transferrin based on the glutathione capped gold nanoclusters (GSH-AuNCs). The GSH-AuNCs were prepared in a simple process by using glutathione as a stabilizer and reduced reagent. Most metal ions could quench the fluorescence of gold nanoclusters. Ferric ions could also make the fluorescence of GSH-AuNCs quench. Furthermore, because of the more important coordination between ferric ions and transferrin, the fluorescence was considerably increased when transferrin was added to the GSH-AuNCs-Fe3+ system. Based on this principle, we have established a new fluorescence method to determine transferrin with high selectivity. The detection limit and limit of quantitation (LOQ) of transferrin were calculated to be 0.06 µM, 0.21 µM in the linear range of 0.2–1.0 µM. Moreover, the mechanism of the fluorescence off–on of this method was also investigated. The proposed method has been shown to have outstanding sensing capability and has been successfully used to determine the transferrin in rat serum samples with the relative recoveries ranged from 94.6 to 110.3%, the RSD intraday and inter-day were below 2.9%.