Highly selective detection of bacterial alarmone ppGpp with an off-on fluorescent probe of copper-mediated silver nanoclusters

In this study, a facile strategy for highly selective and sensitive detection of bacterial alarmone, ppGpp, which is generated when bacteria face stress circumstances such as nutritional deprivation, has been established by developing an off-on fluorescent probe of Cu2+-mediated silver nanoclusters (Ag NCs). This work not only achieves highly selective detection of ppGpp in a broad range concentration of 2-200 μM, but also improves our understanding of the specific recognitions among DNA-Ag NCs, Cu2+, and ppGpp. The present strategy, together with other reports on the Ag NCs-related analytical methods, has also identified that Ag NCs functionalized with different molecules on their surfaces can be engineered fluorescent probes for a wide range of applications such as biosensing and bioimaging.