Use of carbon supports with copper ion as a highly sensitive non-enzymatic glucose sensor

Abstract

Nearly all current non-enzymatic electrochemical glucose sensors involve carefully designed metal/metal oxide nanomaterials and the complications of preparing electrocatalyst increase the fabrication cost and reduce the reproducibility of a sensor. Thus, a simple yet reliable and cost-effective glucose sensing system is much desired. Inspired by the glucose oxidation mechanism of copper-based nanomaterials, we developed a series of highly sensitive electrochemical glucose sensors using micromol level Cu2+ ions as an electrocatalyst. High sensitivities are achieved on various carbon-based electrodes (GCE: 614 mA M−1 cm−2; activated carbon: 1627 mA M−1 cm−2; carbon paper: 2149 mA M−1 cm−2; graphite powder: 1695 mA M−1 cm−2, and functionalized multi-walled carbon nanotube: 1842 mA M−1 cm−2). With short response time (<2 s), large linear range (0.02 μM–2.5 mM and 2.5–8.0 mM), high stability, and excellent tolerance to interference, Cu ion-based sensor was also validated for testing glucose level in real blood samples. Further studies show that carbon support (e.g., MWCNT-COOH) can be doped with nanomolar level Cu2+ to produce a practical solid electrode with an ultra-high sensitivity of 1732 mA M−1 cm−2, retaining the advantage of atomic efficiency. This work provides a new route to the rational design of simple, cheap, and highly effective electrochemical glucose sensors.