title: Light triggered detection of aminophenyl phosphate with a quantum dot based enzyme electrode.
abstract: An electrochemical sensor for p-aminophenyl phosphate (pAPP) is reported. It is based on the electrochemical conversion of 4-aminophenol (4AP) at a quantum dot (QD) modified electrode under illumination. Without illumination no electron transfer and thus no oxidation of 4AP can occur. pAPP as substrate is converted by the enzyme alkaline phosphatase (ALP) to generate 4AP as a product. The QDs are coupled via 1,4-benzenedithiol (BDT) linkage to the surface of a gold electrode and thus allow potential-controlled photocurrent generation. The photocurrent is modified by the enzyme reaction providing access to the substrate detection. In order to develop a photobioelectrochemical sensor the enzyme is immobilized on top of the photo-switchable layer of the QDs. Immobilization of ALP is required for the potential possibility of spatially resolved measurements. Geometries with immobilized ALP are compared versus having the ALP in solution. Data indicate that functional immobilization with layer-by-layer assembly is possible. Enzymatic activity of ALP and thus the photocurrent can be described by Michaelis- Menten kinetics. pAPP is detected as proof of principle investigation within the range of 25 μM-1 mM.
authors: Fachbereich Physik and WZMW, Philipps Universität Marburg, Germany.
authors: Waqas
authors: W
authors: Khalid
authors: Gero
authors: G
authors: Göbel
authors: Dominik
authors: D
authors: Hühn
authors: Jose-Maria
authors: JM
authors: Montenegro
authors: Pilar
authors: P
authors: Rivera-Gil
authors: Fred
authors: F
authors: Lisdat
authors: Wolfgang J
authors: WJ
authors: Parak
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000627:Aminophenols / Q000737:chemistry / Q000378:metabolism*; D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006868:Hydrolysis; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D045663:Quantum Dots
chemical_list: D000627:Aminophenols; D006046:Gold; D000469:Alkaline Phosphatase; C026729:4-aminophenol