Three-dimensional porous Cu@Cu₂O aerogels for direct voltammetric sensing of glucose

Three-dimensional Cu@Cu₂O aerogels with excellent electrocatalytic activity were prepared and used as electrode matrix for constructing novel electrochemical glucose sensors. The aerogels were obtained by adding a fresh solution of NaBH₄ into a mixture of CuCl₂ and NaOH aqueous solutions under stirring at room temperature. The aerogels were assembled with Cu or Cu₂O nanoparticles. The materials show superfine spongy-like structures with large surface-to-volume ratio, numerous active sites and good solubility. The Cu@Cu₂O aerogels show highly efficient electrochemical activity toward glucose oxidation with a relatively low-onset potential (0.25 V) in 0.1 M NaOH solution. This non-enzymatic glucose sensor offers a low detection limit of 0.6 μM (S/N = 3), a high sensitivity (195 mA M^-1 cm^-2), and two wide linear ranges (0.001-5.2 mM, 5.2-17.1 mM) at a working voltage of 0.6 V (vs. Ag/AgCl) in alkaline solution. While in neutral pH values, the respective data are a linear analytical range from 0.1 to 10 mM; a detection limit of 54 μM (S/N = 3) and a sensitivity of 12 mA M^-1 cm^-2 at scan rate of 100 mV s^-1. The sensor possesses high selectivity, good reproducibility and long-time stability. It was utilized to determine glucose levels in (spiked) human serum samples, and satisfactory results were obtained. Graphical abstract Schematic presentation of a glassy carbon electrode modified with 3D porous Cu@Cu₂O aerogels. The aerogels were obtained by a reduction reaction at room temperature (Scheme 1A). The aerogel networks were used to develop a highly sensitive electrochemical sensing platform for the detection of glucose (Scheme 1B).