title: A ready-to-use fluorimetric biosensor for superoxide radical using superoxide dismutase and peroxidase immobilized in sol-gel glasses.
abstract: In this work, a highly sensitive fluorescent biosensor for quantitative superoxide radical detection, based on the coupled reaction superoxide dismutase-peroxidase enzymes and the use of the probe Amplex red, is described. Superoxide anion radical was produced via oxidation of xanthine by xanthine oxidase. Dismutation of superoxide was catalyzed by superoxide dismutase, generating hydrogen peroxide, which reacted stoichiometrically with the nonfluorescent Amplex red, in the presence of peroxidase, yielding the red-fluorescent oxidation product resorufin. The coupled superoxide dismutase-peroxidase system was immobilized in a single sol-gel matrix. The enzymatic activity of the encapsulated superoxide dismutase-peroxidase system was nearly identical to that of one of the soluble enzymes, indicating that sol-gel encapsulation preserved the hierarchy of the enzyme's activity. Specificity and reusability of the encapsulated system for up to four cycles were also demonstrated. The fluorescent biosensor was able to detect concentrations of superoxide as low as 20 nM in phospholipid model membranes composed of saturated or unsaturated phospholipids. These facts make this biosensor a simple, reliable, and highly sensitive method with a potential use in biological systems, food, and drinks.
authors.affiliation: Instituto de Biología Molecular y Celular, Universidad Miguel Hernandez, Elche E-03202, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Pastor
authors.forename: Rocío
authors.initials: R
authors.lastname: Esquembre
authors.forename: Vicente
authors.initials: V
authors.lastname: Micol
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mallavia
authors.forename: C Reyes
authors.initials: CR
authors.lastname: Mateo
mesh_terms: D000838:Anions / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D002138:Calibration; D004134:Dimyristoylphosphatidylcholine / Q000032:analysis / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000737:chemistry; D005470:Fluorometry / Q000295:instrumentation / Q000379:methods*; D005782:Gels / Q000737:chemistry; D005898:Glass; D006735:Horseradish Peroxidase / Q000378:metabolism*; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry; D015394:Molecular Structure; D010078:Oxazines / Q000737:chemistry; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry; D013057:Spectrum Analysis; D013482:Superoxide Dismutase / Q000378:metabolism*; D013481:Superoxides / Q000032:analysis*; D019820:Xanthine
chemical_list: D000838:Anions; D004800:Enzymes, Immobilized; D005456:Fluorescent Dyes; D005782:Gels; D008081:Liposomes; D010078:Oxazines; D012996:Solutions; D013481:Superoxides; C470430:Amplex Red; D019820:Xanthine; D006735:Horseradish Peroxidase; D013482:Superoxide Dismutase; D004134:Dimyristoylphosphatidylcholine