title: Photo-electrochemical Bioanalysis of Guanosine Monophosphate Using Coupled Enzymatic Reactions at a CdS/ZnS Quantum Dot Electrode.
abstract: A photo-electrochemical sensor for the specific detection of guanosine monophosphate (GMP) is demonstrated, based on three enzymes combined in a coupled reaction assay. The first reaction involves the adenosine triphosphate (ATP)-dependent conversion of GMP to guanosine diphosphate (GDP) by guanylate kinase, which warrants substrate specificity. The reaction products ADP and GDPare co-substrates for the enzymatic conversion of phosphoenolpyruvate to pyruvate in a second reaction mediated by pyruvate kinase. Pyruvate in turn is the co-substrate for lactate dehydrogenase that generates lactate via oxidation of nicotinamide adenine dinucleotide (reduced form) NADH to NAD(+). This third enzymatic reaction is electrochemically detected. For this purpose a CdS/ZnS quantum dot (QD) electrode is illuminated and the photocurrent response under fixed potential conditions is evaluated. The sequential enzyme reactions are first evaluated in solution. Subsequently, a sensor for GMP is constructed using polyelectrolytes for enzyme immobilization.
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032, Marburg, Germany.
authors.forename: Nadeem
authors.initials: N
authors.lastname: Sabir
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077, Göttingen, Germany.
authors.forename: Nazimuddin
authors.initials: N
authors.lastname: Khan
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032, Marburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Völkner
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032, Marburg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Widdascheck
authors.affiliation: CIC biomaGUNE, Parque Tecnológico de San Sebastián, P° Miramón 182 - Ed. Empresarial C, 20009, San Sebastian, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: del Pino
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032, Marburg, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Witte
authors.affiliation: Biosystems Technology, Institute of Applied Life Sciences, Technical University Wildau, Hochschulring 1, D-15745, Wildau, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Riedel
authors.affiliation: Biosystems Technology, Institute of Applied Life Sciences, Technical University Wildau, Hochschulring 1, D-15745, Wildau, Germany.
authors.forename: Fred
authors.initials: F
authors.lastname: Lisdat
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077, Göttingen, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Konrad
authors.affiliation: Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032, Marburg, Germany.|CIC biomaGUNE, Parque Tecnológico de San Sebastián, P° Miramón 182 - Ed. Empresarial C, 20009, San Sebastian, Spain.
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Parak
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D019187:Cadmium Compounds / Q000737:chemistry; D003217:Conductometry / Q000295:instrumentation*; D004800:Enzymes, Immobilized; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006157:Guanosine Monophosphate / Q000032:analysis*; D007770:L-Lactate Dehydrogenase / Q000737:chemistry*; D008839:Microelectrodes; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D004800:Enzymes, Immobilized; D018036:Selenium Compounds; D017967:Zinc Compounds; D006157:Guanosine Monophosphate; C058667:cadmium selenide; D007770:L-Lactate Dehydrogenase; C044696:zinc selenide
keywords: bioanalysis; electrodes; enzymes; guanosine monophosphate; photoelectrochemistry; quantum dots