Scientists in the UK have developed a new class of luminescent probe for the biomedical imaging of zinc.

Simon Pope and colleagues at the University of Cardiff have designed a europium-containing luminescent sensor that can selectively detect the presence of zinc in physiological conditions.  

Zinc is essential for human growth and development, and an imbalance of zinc occurs in humans suffering from illnesses such as cancer, diabetes and Alzheimer's disease. However, little is known about the distribution, accumulation and mobility of intracellular zinc. 

Pope's sensor is based on a cyclic organic framework containing europium and a joining arm. When zinc is present it complexes to this arm, causing a detectable change in the red luminescence of the europium ion. 
 
The group have successfully applied the sensor to physiological conditions, so the next major challenge is to apply these sensors to real-life situations. 'If we really want to apply our luminescent probes to biomedical imaging we need to improve the photophysical properties', said Pope. Light with a wavelength that is more compatible with biological tissue could then be used, allowing a greater imaging depth. 

Pope's ultimate goal is to be able to map the distribution of intracellular zinc by magnetic resonance imaging or luminescence imaging. According to Jean-Claude Bunzli at the laboratory of lanthanide supramolecular chemistry in Switzerland, further modification of the framework 'could lead to specific coupling of the sensor, enabling zinc mapping in zones where it is biologically active.'

Jenna Wilson