Colorimetric Cu(2+) detection using DNA-modified gold-nanoparticle aggregates as probes and click chemistry.

Copper is a transition metal essential for life. At elevated concentrations, however, it is highly toxic to organisms such as algae, fungi and many bacteria, and in humans, may adversely affect the gastrointestinal, hepatic and renal systems.[1, 2] As such, the detection and measurement of copper ions in water has become increasingly important, especially in point-of-use formats. Several methods exist for the detection of Cu2+ ions, including those based on organic dyes,[3–6] semiconductor nanocrystals,[7] and spectroscopy.[8–10] The read out mechanisms for these methods, however, often require sophisticated instrumentation. In contrast, colorimetric methods are extremely attractive for point-of-use applications, since they can be easily interpreted with the naked eye or low-cost portable instruments.