DNA-encapsulated silver nanodots are noteworthy candidates for bio-imaging probes, thanks to their excellent photophysical properties. The spectral shift of silver nanodot emitters from red to blue shows excellent correlations with the concentration of reactive oxygen species, which makes it possible to develop new types of probes for reactive oxygen species (ROS), such as hypochlorous acid (HOCl), given the outstanding stability of the blue in oxidizing environments. HOCl plays a role as a microbicide in immune systems but, on the other hand, is regarded as a disease contributor. Moreover, it is a common ingredient in household cleaners. There are still great demands to detect HOCl fluxes and their physiological pathways. We introduce a new ratiometric luminescence imaging method based on silver nanodots to sensitively detect hypochlorite. The factors that influence the accuracy of the detection are investigated. Its availability has also been demonstrated by detecting the active component in cleaners.PACS82; 82.30.Nr; 82.50.-m