A high sensitivity amperometric biosensor using a monomolecular layer of laccase as biorecognition element.
Laccases from various sources were tested, and laccase from Rigidoporus lignosus was found to be the most active towards syringaldazine and ABTS, which are typical substrates of this class of enzymes, and towards the phenols found in olive oil mill wastewaters. This laccase was covalently immobilised by carbodiimide chemistry, on a self-assembled monolayer of 3-mercaptopropionic acid deposited on a gold surface. A flow biosensor, using the monolayer of laccase as bioelement and a glassy carbon electrode as amperometric transduction system, was developed. Although the amount of the immobilised enzyme (about 140 ng/cm2 effective surface area) was tiny, the biosensor showed a sensitivity of 3 nA/microM when 1,4-hydroquinone was used as substrate, and a half-life of 35 days. The proposed device permits detection of phenols in aqueous solutions at concentrations in the low micromolar range, i.e. below European Community limits. The biosensor was successfully used to detect phenols in wastewaters from an olive oil mill after minimal sample preparation (incubation of the aqueous sample with sodium borohydride for a few minutes) to suppress the current due to oxidised compounds present in the wastewaters.
Vianello
Fabio
F
Department of Biological Chemistry, University of Padua, Viale G. Colombo 3, 35121 Padua, Italy.
Cambria
Antonio
A
Ragusa
Santa
S
Cambria
Maria Teresa
MT
Zennaro
Lucio
L
Rigo
Adelio
A
D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007220:Industrial Waste / Q000032:analysis*; D042845:Laccase / Q000032:analysis / Q000737:chemistry* / Q000145:classification; D000069463:Olive Oil; D010636:Phenols / Q000032:analysis* / Q000737:chemistry*; D010938:Plant Oils / Q000032:analysis / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014874:Water Pollutants, Chemical / Q000032:analysis*
D020099:Coated Materials, Biocompatible; D004800:Enzymes, Immobilized; D007220:Industrial Waste; D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils; D014874:Water Pollutants, Chemical; D042845:Laccase