Sensitive detection of copper(II) by a commercial glucometer using click chemistry.

The commercially available glucometer has been the most successful point-of-care (POC) sensor up to date. However, the glucometer only responds to glucose rather than other species. Extending the use of the glucometer for monitoring different types of targets would potentially revolutionize the applicability of the glucometer. Here we report a new sensing strategy for sensitive and selective detection of Cu(2+) based on multi-invertase conjugated magnetic bead signal amplification labels and a glucometer transducer. The Cu(2+) is in situ reduced to Cu(+) by sodium ascorbate, which catalyzes the click linking between the alkynyl-DNA immobilized on a disposable screen printed carbon electrode and the azido-DNA attached to the invertase/magnetic bead conjugates. The numerous invertase on the magnetic bead labels through Cu(+)-catalyzed click chemistry reaction convert sucrose to glucose, which is monitored by the glucometer and offers amplified digital readings for Cu(2+) detection. By employing the multi-invertase signal amplification, as low as 10nM Cu(2+) can be detected. Our method also shows high selectivity for Cu(2+) against other metal ions owing to the highly specific Cu(+)-catalyzed click chemistry reaction, and is applicable for monitoring Cu(2+) in real river samples. Our strategy can be easily expanded for the monitoring of a wide range of targets when coupled with various recognition events.