New Zinc Sensor Developed
25 April 2007
As described in an article featured by the Royal Society of Chemistry, Simon Pope has designed a europium-containing luminescent sensor that can selectively detect the presence of zinc in physiologically modelled conditions.
Zinc is essential for human growth and development, and an imbalance of zinc often 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 tetraaza macrocyclic organic framework containing a luminescent europium ion and a chromophoric binding site for zinc based upon a tris-pyridylamine unit. When zinc is present it binds to the pyridyl units, causing a detectable change in both the spectral form and lifetime of the red emission of the europium ion. This occurs because binding zinc alters the coordination environment of the europium ion by increasing the number of water molecules coordinated to the metal ion.
Due to the function of the probe, which changes the coordination environment of the lanthanide ion upon binding zinc, this approach should also be ideally suited to magnetic resonance imaging (MRI) where the coordination of water to gadolinium is key to MRI.
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 assess them intracellularly (in collaboration with the School of Pharmacy at Cardiff University) and optimise the photophysical properties", said Pope. For example, near-infrared (NIR) wavelength light is more compatible with biological tissue, allowing a greater imaging depth: the group are already looking at NIR emissive analogues of the europium system.
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."