title: Laccase-Prussian blue film-graphene doped carbon paste modified electrode for carbamate pesticides quantification.
abstract: A novel enzymatic biosensor for carbamate pesticides detection was developed through the direct immobilization of Trametes versicolor laccase on graphene doped carbon paste electrode functionalized with Prussian blue films (LACC/PB/GPE). Graphene was prepared by graphite sonication-assisted exfoliation and characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The Prussian blue film electrodeposited onto graphene doped carbon paste electrode allowed considerable reduction of the charge transfer resistance and of the capacitance of the device. The combined effects of pH, enzyme concentration and incubation time on biosensor response were optimized using a 2(3) full-factorial statistical design and response surface methodology. Based on the inhibition of laccase activity and using 4-aminophenol as redox mediator at pH 5.0, LACC/PB/GPE exhibited suitable characteristics in terms of sensitivity, intra- and inter-day repeatability (1.8-3.8% RSD), reproducibility (4.1 and 6.3% RSD), selectivity (13.2% bias at the higher interference:substrate ratios tested), accuracy and stability (ca. twenty days) for quantification of five carbamates widely applied on tomato and potato crops. The attained detection limits ranged between 5.2×10(-9)molL(-1) (0.002mgkg(-1) w/w for ziram) and 1.0×10(-7)molL(-1) (0.022mgkg(-1) w/w for carbofuran). Recovery values for the two tested spiking levels ranged from 90.2±0.1 (carbofuran) to 101.1±0.3% (ziram) for tomato and from 91.0±0.1% (formetanate) to 100.8±0.1% (ziram) for potato samples. The proposed methodology is appropriate to enable testing pesticide levels in food samples to fit with regulations and food inspections.
authors.affiliation: REQUIMTE, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua Dr. Bernardino de Almeida 431, 4200-072 Porto, Portugal.
authors.forename: Thiago M B F
authors.initials: TM
authors.lastname: Oliveira
authors.forename: M
authors.initials: M
authors.lastname: Fátima Barroso
authors.forename: Simone
authors.initials: S
authors.lastname: Morais
authors.forename: Mariana
authors.initials: M
authors.lastname: Araújo
authors.forename: Cristina
authors.initials: C
authors.lastname: Freire
authors.forename: Pedro
authors.initials: P
authors.lastname: de Lima-Neto
authors.forename: Adriana N
authors.initials: AN
authors.lastname: Correia
authors.forename: Maria B P P
authors.initials: MB
authors.lastname: Oliveira
authors.forename: Cristina
authors.initials: C
authors.lastname: Delerue-Matos
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D002219:Carbamates / Q000302:isolation & purification*; D002244:Carbon / Q000737:chemistry; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D005295:Ferrocyanides / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D042845:Laccase / Q000737:chemistry; D057230:Limit of Detection; D010575:Pesticides / Q000302:isolation & purification*; D056951:Photoelectron Spectroscopy
chemical_list: D002219:Carbamates; D004800:Enzymes, Immobilized; D005295:Ferrocyanides; D010575:Pesticides; D002244:Carbon; D006108:Graphite; D042845:Laccase; C000170:ferric ferrocyanide