title: Enzyme-induced modulation of the emission of upconverting nanoparticles: towards a new sensing scheme for glucose.
abstract: A new approach for the design of a fluorometric biosensor for continuous monitoring of glucose levels in biological samples based on near-infrared (NIR) excitation is described. The sensor combines the fluorescence of the enzyme glucose oxidase (GOx) chemically modified with a fluorescein derivative (FS) and the luminescent properties of upconverting luminescent nanoparticles (UCLNPs). Both, the chemically modified enzyme (GOx-FS) and the UCLNPs are immobilized in a poly(acrylamide) film as a physical support. The excitation of the UCLNPs with NIR light is of major advantage, since fluorescence background from the matrix is minimized. The upconverted luminescence is used to excite GOx-FS, which undergoes a change in the fluorescence intensity during the enzymatic reaction with glucose. The sensor comprises sufficient stability and covers the physiological range of glucose levels in blood. Furthermore, in a proof of principle experiment, the sensor system responds linearly to glucose concentrations in the range from 3.3 to 16.6 mM in flow injection analysis mode.
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg, Germany; Group of Chemical Technology for Separation and Detection, Instituto de Carboquímica - CSIC, 50018 Zaragoza, Spain; Analytical Biosensors Group (GBA), Analytical Chemistry Department, Faculty of Science, Aragon Institute of Nanoscience (INA), University of Zaragoza, 50018 Zaragoza, Spain.
authors.forename: Melisa
authors.initials: M
authors.lastname: del Barrio
authors.affiliation: Analytical Biosensors Group (GBA), Analytical Chemistry Department, Faculty of Science, Aragon Institute of Nanoscience (INA), University of Zaragoza, 50018 Zaragoza, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: de Marcos
authors.affiliation: Group of Chemical Technology for Separation and Detection, Instituto de Carboquímica - CSIC, 50018 Zaragoza, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Cebolla
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Heiland
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wilhelm
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hirsch
authors.affiliation: Analytical Biosensors Group (GBA), Analytical Chemistry Department, Faculty of Science, Aragon Institute of Nanoscience (INA), University of Zaragoza, 50018 Zaragoza, Spain. Electronic address: jgalban@unizar.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Galbán
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D001234:Aspergillus niger / Q000201:enzymology; D015374:Biosensing Techniques / Q000295:instrumentation*; D001786:Blood Glucose / Q000032:analysis; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000378:metabolism; D004867:Equipment Design; D017022:Flow Injection Analysis; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000378:metabolism; D006801:Humans; D057230:Limit of Detection; D049449:Luminescence; D049408:Luminescent Agents / Q000737:chemistry*; D008163:Luminescent Measurements / Q000295:instrumentation; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D001786:Blood Glucose; D004800:Enzymes, Immobilized; D005947:Glucose; D005949:Glucose Oxidase; D049408:Luminescent Agents; D000099166:Polyacrylamides
keywords: Glucose biosensor; Glucose oxidase; Near-infrared excitation; Upconverting nanoparticles