Determination of β-glucosidase activity in soils with a bioanalytical sensor modified with multiwall 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

Soil microorganisms and enzymes are the primary mediators of soil biologicalprocesses, including organic matter degradation, mineralization and nutrient recycling.They play an important role in maintaining soil ecosystem quality and functionaldiversity. Moreover enzyme activities can provide indication for quantitative changes insoil organic matter (SOM). β-glucosidase (β-Glu) activity has been found to be sensitiveto soil management and has been proposed as a soil quality indicator because it providesan early indication of changes in organic matter status and its turnover. The aims of thepresent study were test and use a simple and convenient procedure for the assay of β-Glu activity in agricultural soil. The method described here is based on the enzymicdegradation of cellobiose by β-Glu present in the soil sample and the subsequentdetermination of glucose produced by the enzymatic reaction using Screen-printedcarbon electrodes (SPCE) modified with multiwalled carbon nanotubes (MWCNT)(SPCE-CNT) equipped with co-immobilized glucose oxidase (GOD) and horseradishperoxidase (HRP) enzymes. The potential applied to the SPCE-CNT detection was−0.15V versus Ag/AgCl pseudo-reference electrode. The linear calibration curve wasobtained in the range of 2.7 10-3–11.3 mM with a correlation coefficient. In the presentstudy, an easy and effective SPCE-CNT modified electrode allowed an improvedamperometric response and this is attributed to the increased surface area upon electrodemodification