Trace levels of mercury in fish organs can be detected using a two-photon fluorescent probe designed by Korean scientists. 

Mercury is a notoriously toxic element that can damage DNA and disrupt the central nervous and endocrine systems. It is released into the environment through volcanic activity, coal production and industrial waste. Fish living in polluted water are particularly susceptible to poisoning, as the mercury can be taken in through the mouth or skin and becomes deposited in their organs. 

Detection of trace amounts of mercury ion pollutants is important to detect early stages of contamination explains Bong Rae Cho at the University of Korea, Seoul. One photon mercury probes that can detect toxic levels of mercury in fish samples are available but the tissue must be treated with nitric acid in a microwave first. Cho's probe uses two photons at a lower energy that can penetrate samples deeply without the need for further treatment. 

The mercury's distribution and accumulation in the organs can be imaged and trace concentrations can be estimated using the probe. 'Our probe will have useful applications in detecting mercury ions in almost any tissues of living matter, such as fish, human organs, and vegetables,' says Cho. 

Cho adds that the relationship between the mercury ion content and its distribution in the poisoned area given by the probe could improve the understanding of mercury ion poisoning in human tissue and possibly help to find a cure.

'[This work] impressively combines features of original probe design, analytical importance and state-of-the-art instrumentation to tackle the problem of mercuric ion determination in life cells, realizing a high selectivity and a low limit of detection in appreciably short measurement times.' Comments Knut Rurack, an expert in bioanalytical sensors at the BAM Federal Institute for Materials Research and Testing, Berlin, Germany.

The team are also developing two photon probes for detecting other heavy metal pollutants, such as cadmium and lead. Such probes lead the way towards solving environmental issues like heavy metal pollution and have the potential to be used for medical applications or used by environmental agencies in the future, Cho concludes. 

Emma Shiells 

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