doi:10.1038/nindia.2012.122 Published online 23 August 2012
Researchers have developed a new fluorescent chemosensor that can detect excess levels of copper ions in biological and environmental samples. This sensor could prove useful in detecting and removing excess levels of these metal ions from live cells.
Although copper ions play vital roles in biological processes, excess levels of copper can damage the infant liver and migrate to the brain, causing neurodegenerative disorders like Alzheimer's and Parkinson's disease in adults. Existing techniques to detect copper ions are tedious and expensive.
To find a suitable sensor that could enable detection with the naked eye, the researchers developed chemosensors using rhodamine-derived fluorescent molecules. They developed four chemosensors (A, B, C, and D) using rhodamine hydrazide, then tested the metal ion-binding efficacy of these sensors on exposure to solutions containing copper and various other metal ions.
Among these, chemosensor D containing triazole compound showed selective binding to copper ions.
To determine the lower limit of detection, a fixed concentration of chemosensor D was exposed to varying concentrations of copper ions at room temperature and physiological pH. Presence of even one micromole of copper ions could increase the fluorescence of chemosensor D.
Commonly coexisting metal ions did not show any effects on the copper ion-induced fluorescence emitted by D, indicating its ability to detect copper ions even in the presence of high concentrations of biologically relevant metal ions such as sodium, magnesium, zinc, calcium and potassium. Chemosensor D exhibited considerable fluorescence only below pH 4, showing that it could be used for sensing copper ions in biological samples.
"Mouse fibroblasts treated with both copper ions and chemosensor D displayed intense red fluorescence, suggesting the suitability of chemosensor D for bio-imaging applications," says Sathiah Thennarasu, one of the researchers.
The authors of this work are from: Organic Chemistry Division, and Chemical Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai, India.