title: Quantum-dot-modified electrode in combination with NADH-dependent dehydrogenase reactions for substrate analysis.
abstract: A quantum dot-electrode system was developed which allows the sensitive detection of NADH (nicotinamide adenine dinucleotide). The colloidal semiconductive CdSe/ZnS nanocrystals (quantum dots) are attached to gold by chemisorption via a dithiol compound. The current signal can be triggered by illumination of the quantum-dot-modified electrode surface. Because of photoexcitation, electron-hole pairs are generated in the quantum dots, which can be detected as anodic or cathodic photocurrent. The immobilization of the nanocrystals is verified by amperometric photocurrent and quartz crystal microbalance (QCM) measurements. This study shows that CdSe/ZnS quantum dot-modified electrodes allow concentration dependent NADH detection in the range of 20 microM to 2 mM already at rather low potentials (around 0 V vs. Ag/AgCl, 1 M KCl). Therefore such electrodes can be used in combination with NADH-producing enzyme reactions for the light-triggered analysis of the respective substrates of the biocatalyst. It can be shown that glucose detection is feasible with such an electrode system and photocurrent measurements.
authors.affiliation: Biosystems Technology, University of Applied Sciences Wildau, Bahnhofstrasse 1, 15745 Wildau, Germany.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Schubert
authors.forename: Waqas
authors.initials: W
authors.lastname: Khalid
authors.forename: Zhao
authors.initials: Z
authors.lastname: Yue
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Parak
authors.forename: Fred
authors.initials: F
authors.lastname: Lisdat
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D004566:Electrodes; D009245:NADH Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D036103:Nanotechnology; D010777:Photochemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D019287:Zinc Sulfate / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D019287:Zinc Sulfate; C058667:cadmium selenide; D009245:NADH Dehydrogenase