title: A reagentless optical biosensor based on the intrinsic absorption properties of peroxidase.
abstract: During the reversible reaction between peroxidase (HRP) and H(2)O(2), several peroxidase intermediate species, showing different molecular absorption spectra, are formed which can be used for H(2)O(2) determination; when H(2)O(2) is generated in a previous enzymatic reaction, the substrate involved in this reaction can also be determined. On this basis, a new family of fully reversible reagentless optical biosensors containing HRP is presented; glucose determination is used as a model. The biosensor (which can be used for at least 6 months and/or more than 750 measurements) is prepared by HRP and glucose oxidase entrapment in a polyacrylamide gel matrix. A mathematical model (in which optical, kinetic and transport aspects are considered) relating the measured absorbance with the substrate concentration is also presented together with a simple methodology for characterization of this kind of biosensor. Regarding the optical model, the Kubelka-Mulk theory of reflectance does not give good results and the biosensors are better described by the Rayleigh theory of polymer solutions. Under working conditions, linear response ranges from 1.5x10(-6) to 3.0x10(-4)M glucose and CV was about 4%. This biosensor has been applied for glucose determination in fruit juices and synthetic serum samples without sample pretreatment.
authors.affiliation: Analytical Biosensors Group, Institute of Nanotechnology of Aragón, Analytical Chemistry Department, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Sanz
authors.forename: Susana
authors.initials: S
authors.lastname: de Marcos
authors.forename: Javier
authors.initials: J
authors.lastname: Galbán
mesh_terms: D000042:Absorption; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D001786:Blood Glucose / Q000032:analysis*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005949:Glucose Oxidase / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000032:analysis*; D007202:Indicators and Reagents; D008956:Models, Chemical; D055095:Optics and Photonics / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods
chemical_list: D001786:Blood Glucose; D007202:Indicators and Reagents; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D006735:Horseradish Peroxidase