Quantitation of β-galactosidase and E. coli through electrochemical oxidation of glucose on CuO/Cu2O/Ppy paper electrode

Linen texture (LT) paper functionalized with CuO/Cu2O/Ppy composite has been prepared and used separately as an electrode for quantitation of glucose, b-galactosidase, and Escherichia coli (E. coli). The low-cost CuO/Cu2O/Ppy LT paper is prepared through a two-step process; pyrrole adsorbed on an LT paper reacts with Cu2+ in the presence of ascorbic acid and fructose to form Cu2O/Ppy that then reacts with Cu2+ in the presence of cetyltrimethylammonium bromide. The CuO/Cu2O/Ppy LT paper electrode possessing glucose oxidase-like activity catalyzes the oxidation of glucose, allowing quantitation of glucose down to 0.04 mM. To enhance the mass transfer efficiency and reduce the sample volume, CuO/Cu2O/Ppy LT paper microelectrodes with an area of 0.12 cm(2) have been fabricated. By taking the specificity of beta-galactosidase for the conversion of lactose to form glucose, the paper microelectrode has been employed for the quantitation of b-galactosidase and of E. coli as low as 0.034 U mL-1 and 120 CFU mL-1, respectively. In addition, this assay is powerful for screening of activators/inhibitors of b-galactosidase and the antibiotic activities toward E. coli. The inexpensive and stable CuO/Cu2O/Ppy LT paper electrode is sensitive for quantitation of glucose, b-galactosidase, and E. coli, as well as for drug screening.(C) 2017 Elsevier B.V. All rights reserved.