Green synthesis of starch-capped Cu2O nanocubes and their application in the direct electrochemical detection of glucose.

Glucose determination is an essential procedure in different fields, used in clinical analysis for the prevention and monitoring of diabetes. In this work, modified carbon paste electrodes with Cu2O nanocubes (Cu2O NCs) were developed to test electrochemical glucose detection. The synthesis of the Cu2O NCs was achieved by a green method using starch as the capping agent, obtaining cubic-like morphologies and particle sizes from 227 to 123 nm with increasing amounts of the capping agent, as corroborated by electron microscopy analysis. Their crystalline structure and purity were determined by X-ray diffraction. The capability of starch as a capping agent was verified by Fourier-transform infrared spectroscopy, in which the presence of functional groups of this biopolymer in the Cu2O NCs were identified. The electrochemical response to glucose oxidation was determined by cyclic voltammetry, obtaining a linear response of the electrical current as a function of glucose concentration in the range 100-700 µM, with sensitivities from 85.6 to 238.8 µA mM-1 cm-2, depending on the amount of starch used in the synthesis of the Cu2O NCs.