Scientists in South Korea have developed a new probe for mercury that can be used for imaging organs in living organisms.

Mercury is a highly toxic and widespread pollutant. But whilst a number of fluorescence probes exist for mercury most detect only its inorganic forms; there are few reports of probes for organic mercury species such as methylmercury. Yet, the element is commonly found in organic forms, which are more toxic than inorganic mercury as their lipophilicity allows them to cross biological membranes. Consequently, new ways of detecting these mercury species, particularly in organisms, is of crucial importance.

Now, Kyo Han Ahn of Pohang University of Science and Technology, Injae Shin of Yonsei University and colleagues have addressed this need. They have developed a structurally simple probe which reacts with both organic and inorganic mercury to give a fluorescent product. They have used the probe to monitor mercury species in mammalian cells and zebrafish organs incubated with organic mercury.

While previous probes for inorganic mercury used sulfur-based ligands, Ahn and Shin's approach takes advantage of different chemistry, as Amirla de Silva, an expert in fluorescent sensors at Queen's University, Belfast, UK, explains. 'Ahn and his colleagues have taken inspiration from the field of oxymercuration reactions. This is a nice conceptual advance.' De Silva adds that as the reaction between the probe and mercury is irreversible, the probe is essentially a chemodosimeter - or reagent - rather than a sensor. 'Nevertheless, a chemodosimeter for methylmercury is an important step in permitting the monitoring of this severe poison in life forms.'

Ahn agrees and says the probe could be vital to the study of mercury poisoning. 'Now we have a molecular probe that can be used for studying and tracing notoriously toxic methylmercury in living species. By using the probe, we may study the distribution and fate of methylmercury in organisms,' he explains.

The next step is to develop a probe that is more discriminating. 'One of the most challenging issues in mercury sensing is to discriminate inorganic mercury from methylmercury,' says Ahn. 'We do not have such a molecular probe yet but we are working on it.'

Edward Morgan

Enjoy this story? Spread the word using the 'tools' menu on the left or add a comment to the Chemistry World blog.