title: Biosensor based on atemoya peroxidase immobilised on modified nanoclay for glyphosate biomonitoring.
abstract: A biosensor based on atemoya peroxidase immobilised on modified nanoclay was developed for the determination of glyphosate by the enzyme inhibition method. The inhibitor effect of the biocide results in a decrease in the current response of the hydroquinone that was used as a phenolic substrate to obtain the base signal. The biosensor was constructed using graphite powder, multiwalled carbon nanotubes, peroxidase immobilised on nanoclay and mineral oil. Square-wave voltammetry was utilised for the optimisation and application of the biosensor, and several parameters were investigated to determine the optimum experimental conditions. The best performance was obtained using a 0.1 mol L(-1) phosphate buffer solution (pH 7.0), 1.9×10(-4) mol L(-1) hydrogen peroxide, a frequency of 30 Hz, a pulse amplitude of 50 mV and a scan increment of 4 mV. The glyphosate concentration response was linear between 0.10 and 4.55 mg L(-1) with a detection limit of 30 μg L(-1). The average recovery of glyphosate from spiked water samples ranged from 94.9 to 108.9%. The biosensor remained stable for a period of eight weeks.
authors.affiliation: Departamento de Química, Grupo de Eletroquímica e Novos Materiais, Universidade Federal de Mato Grosso, 78060-900, Cuiabá, MT, Brazil.
authors.forename: Grasielli C
authors.initials: GC
authors.lastname: Oliveira
authors.forename: Sally K
authors.initials: SK
authors.lastname: Moccelini
authors.forename: Marilza
authors.initials: M
authors.lastname: Castilho
authors.forename: Ailton J
authors.initials: AJ
authors.lastname: Terezo
authors.forename: Juliana
authors.initials: J
authors.lastname: Possavatz
authors.forename: Márcia R L
authors.initials: MR
authors.lastname: Magalhães
authors.forename: Eliana F G C
authors.initials: EF
authors.lastname: Dores
mesh_terms: D000538:Aluminum Silicates; D029061:Annonaceae / Q000737:chemistry* / Q000201:enzymology; D015374:Biosensing Techniques; D002021:Buffers; D000077215:Clay; D055664:Electrochemical Techniques; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000737:chemistry; D005998:Glycine / Q000031:analogs & derivatives* / Q000032:analysis; D006108:Graphite; D006540:Herbicides / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones / Q000737:chemistry; D057230:Limit of Detection; D008899:Mineral Oil; D037742:Nanotubes, Carbon; D009195:Peroxidase / Q000737:chemistry*; D010710:Phosphates; D010940:Plant Proteins / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D000097797:Glyphosate
chemical_list: D000538:Aluminum Silicates; D002021:Buffers; D000077215:Clay; D004800:Enzymes, Immobilized; D005998:Glycine; D006108:Graphite; D006540:Herbicides; D006873:Hydroquinones; D008899:Mineral Oil; D037742:Nanotubes, Carbon; D009195:Peroxidase; D010710:Phosphates; D010940:Plant Proteins; D014874:Water Pollutants, Chemical; D000097797:Glyphosate; C031927:hydroquinone