Well-aligned Cu@C nanocubes for highly efficient nonenzymatic glucose detection in human serum

Abstract

Unique and well-aligned Cu@C core-shell nanocubes were rationally designed for nonenzymatic glucose detection using cubic Cu2O nanoparticles immerged in water-soluble polyvinyl pyrrolidone (PVP) coatings as precursor. As a consequence, the optimum Cu@C nanocubes with a shell thickness of ∼6.48 nm were prepared by the initial coating of Cu2O nanoparticles with 1.5 mg/mL PVP and subsequent annealing at 600 °C. After thermal annealing process, Cu2O nanoparticles were reduced to Cu nanocubes; at the same time, PVP was pyrolyzed to carbon shell encapulating the cubic Cu core. Due to efficient protection of the carbon shell of Cu core from oxidization and the advantageous inter-connected core-shell conductive networks, the hierarchical Cu@C nanocubes exhibit excellent electrocatalytic activity towards glucose oxidation. Under optimum condition, the resulted 600 °C annealed 1.5 mg/mL-Cu@C/Nafion modified glassy carbon electrode displayed high efficient nonenzymatic glucose detection, offering a wide linear range of 40 μM – 40 mM, with low detection limit at 21.35 μM (S/N = 3) and high sensitivity peak of 2565 μA mM–1 cm–2. More importantly, the well-designed Cu@C core-shell nanocubes could be utilized as a promising nonenzymatic sensor in practical biological applications for the detection of glucose concentration in human serum samples.