title: Light-controlled bioelectrochemical sensor based on CdSe/ZnS quantum dots.
abstract: This study reports on the oxygen sensitivity of quantum dot electrodes modified with CdSe/ZnS nanocrystals. The photocurrent behavior is analyzed for dependence on pH and applied potential by potentiostatic and potentiodynamic measurements. On the basis of the influence of the oxygen content in solution on the photocurrent generation, the enzymatic activity of glucose oxidase is evaluated in solution. In order to construct a photobioelectrochemical sensor which can be read out by illuminating the respective electrode area, two different immobilization methods for the fixation of the biocatalyst have been investigated. Both covalent cross-linking and layer-by-layer deposition of GOD by means of the polyelectrolyte polyallylamine hydrochloride show that a sensor construction is possible. The sensing properties of this type of electrode are drastically influenced by the amount and density of the enzyme on top of the quantum dot layer, which can be advantageously adjusted by the layer-by-layer technique. By depositing four bilayers [GOD/PAH](4) on the CdSe/ZnS electrode, a fast-responding sensor for the concentration range of 0.1-5 mM glucose can be prepared. This study opens the door to multianalyte detection with a nonstructured sensing electrode, localized enzymes, and spatial read-out by light.
authors.affiliation: Biosystems Technology, Technical University Wildau, 15745 Wildau, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Tanne
authors.forename: D
authors.initials: D
authors.lastname: Schäfer
authors.forename: W
authors.initials: W
authors.lastname: Khalid
authors.forename: W J
authors.initials: WJ
authors.lastname: Parak
authors.forename: F
authors.initials: F
authors.lastname: Lisdat
mesh_terms: D015374:Biosensing Techniques; D019187:Cadmium Compounds / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D005947:Glucose / Q000032:analysis; D005949:Glucose Oxidase / Q000737:chemistry / Q000378:metabolism; D055767:Immobilized Proteins / Q000737:chemistry / Q000378:metabolism; D008027:Light; D010100:Oxygen / Q000737:chemistry; D011073:Polyamines / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D055767:Immobilized Proteins; D011073:Polyamines; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C063994:polyallylamine; C058667:cadmium selenide; D005949:Glucose Oxidase; D005947:Glucose; C031238:zinc sulfide; D010100:Oxygen