title: Biosensor based on laccase and an ionic liquid for determination of rosmarinic acid in plant extracts.
abstract: Novel biosensors based on laccase from Aspergillus oryzae and the ionic liquids (ILs) 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMIPF(6)) and 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIBF(4)) were constructed for determination of rosmarinic acid by square-wave voltammetry. The laccase catalyzes the oxidation of rosmarinic acid to the corresponding o-quinone, which is electrochemically reduced back to rosmarinic acid at +0.2V vs. Ag/AgCl. The biosensor based on BMIPF(6) showed a better performance than that based on BMIBF(4). The best performance was obtained with 50:20:15:15% (w/w/w/w) of the graphite powder:laccase:Nujol:BMIPF(6) composition in 0.1mol L(-1) acetate buffer solution (pH 5.0). The rosmarinic acid concentration was linear in the range of 9.99 x 10(-7) to 6.54 x 10(-5)mol L(-1) (r=0.9996) with a detection limit of 1.88 x 10(-7)mol L(-1). The recovery study for rosmarinic acid in plant extract samples gave values from 96.1 to 105.0% and the concentrations determined were in agreement with those obtained using capillary electrophoresis at the 95% confidence level. The BMIPF(6)-biosensor demonstrated long-term stability (300 days; 920 determinations) and reproducibility, with a relative standard deviation of 0.56%.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Franzoi
authors.forename: Jairton
authors.initials: J
authors.lastname: Dupont
authors.forename: Almir
authors.initials: A
authors.lastname: Spinelli
authors.forename: Iolanda Cruz
authors.initials: IC
authors.lastname: Vieira
mesh_terms: D001236:Aspergillus oryzae / Q000378:metabolism; D015374:Biosensing Techniques; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002934:Cinnamates / Q000032:analysis*; D053630:Depsides / Q000032:analysis*; D004563:Electrochemistry / Q000379:methods; D019075:Electrophoresis, Capillary / Q000379:methods; D006108:Graphite; D006863:Hydrogen-Ion Concentration; D052578:Ionic Liquids / Q000032:analysis*; D007477:Ions; D042845:Laccase / Q000032:analysis*; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry; D010936:Plant Extracts / Q000032:analysis*; D011809:Quinones / Q000032:analysis; D000097123:Rosmarinic Acid
chemical_list: D002934:Cinnamates; D053630:Depsides; D006108:Graphite; D052578:Ionic Liquids; D007477:Ions; D042845:Laccase; D010100:Oxygen; D010936:Plant Extracts; D011809:Quinones; D000097123:Rosmarinic Acid