Determination of B-glucosidase activity in soils 5 with a bioanalytical sensor modified with multiwalled 6 carbon nanotubes

PATRICIA W. STEGE; GERMÁN A. MESSINA; GUILLERMO BIANCHI; ROBERTO A. OLSINA; JULIO RABA

ANALYTICAL AND BIOANALYTICAL CHEMISTRY

SPRINGER HEIDELBERG

Año: 2010 vol. 397 p. 1347 - 1353

1618-2642

Abstract Soil microorganisms and enzymes are the primarymediators of soil biological processes, including organicmatter degradation, mineralization, and nutrient recycling.They play an important role in maintaining soil ecosystemquality and functional diversity. Moreover, enzyme activitiescan provide an indication of quantitative changes in soilorganic matter. β-Glucosidase (β-Glu) activity has beenfound to be sensitive to soil management and has beenproposed as a soil quality indicator because it provides anearly indication of changes in organic matter status and itsturnover. The aims of the present study were to test and usea simple and convenient procedure for the assay of β-Gluactivity in agricultural soil. The method described here isbased on the enzymatic degradation of cellobiose by β-Glupresent in the soil sample and the subsequent determinationof glucose produced by the enzymatic reaction usingscreen-printed carbon electrodes modified with multiwalledcarbon nanotubes (SPCE-CNT) equipped with coimmobilizedglucose oxidase and horseradish peroxidase enzymes.The potential applied to the SPCE-CNT detection was−0.15 V versus a Ag/AgCl pseudo-reference electrode. Alinear calibration curve was obtained in the range 2.7–11.3 mM with a correlation coefficient. In the present study,an easy and effective SPCE-CNT-modified electrodeallowed an improved amperometric response to be achievedand this is attributed to the increased surface area uponelectrode modification.