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 Cu2+ based on multi-invertase conjugated magnetic bead signal amplification labels and a glucometer transducer. The Cu2+ 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 Cu2+ detection. By employing the multi-invertase signal amplification, as low as 10 nM Cu2+ can be detected. Our method also shows high selectivity for Cu2+ against other metal ions owing to the highly specific Cu+-catalyzed click chemistry reaction, and is applicable for monitoring Cu2+ 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.

► A commercial glucometer is used as the signal transducer to achieve sensitive detection of copper(II).
► The copper(II) detection is based on highly specific Cu(I)-catalyzed click chemistry through in situ reduction of copper(II).
► Multi-enzyme-loaded microbeads are employed as labels to amplify the signal output to achieve nanomolar detection of copper(II).