Glucose Oxidase and Horseradish Peroxidase Like Activities of Cuprous Oxide/Polypyrrole Composites

Cu₂O/Ppy composites coated linen texture (LT) papers possess enzyme activities of glucose oxidase (GOx) and horseradish peroxidase (HRP) in alkaline solution (0.5 M NaOH). At the potential of 0 V vs. Ag/AgCl reference electrode, H₂O₂ was produced through oxidation of glucose on the functional LT paper electrode in the presence of O₂. The as-produced H₂O₂ was reduced on the electrode at the potential of −0.57 V vs. Ag/AgCl reference electrode. Cyclic voltammograms (CVs) reveal that Cu(I)/Cu(II), Cu(II)/Cu(I), and Cu(I)/Cu transitions occur at ca. 0, −0.57, and −0.85 V respectively. The electrode allows detections of glucose and H₂O₂ down to 0.16 and 0.41 mM, respectively. The high catalytic activity of the Cu₂O/Ppy composites is attributed to the stable coatings of Ppy and the high-index facets of Cu₂O octahedra and microflowers. Having advantages of a low onset potential (ca. −0.02 V), high sensitivity (28 μA mM⁻¹ cm⁻²), and selectivity, the stable and durable LT paper electrode has been validated for the quantitation of glucose in blood samples, showing its great potential for monitoring blood glucose levels.