title: Piezoelectric affinity sensors for cocaine and cholinesterase inhibitors.
abstract: We report here the development of piezoelectric affinity sensors for cocaine and cholinesterase inhibitors based on the formation of affinity complexes between an immobilized cocaine derivative and an anti-cocaine antibody or cholinesterase. For both binding reactions benzoylecgonine-1,8-diamino-3,4-dioxaoctane (BZE-DADOO) was immobilized on the surface of the sensor. For immobilization, pre-conjugated BZE-DADOO with 11-mercaptomonoundecanoic acid (MUA) via 2-(5-norbornen-2,3-dicarboximide)-1,1,3,3-tetramethyluronium-tetrafluoroborate (TNTU) allowed the formation of a chemisorbed monolayer on the piezosensor surface. The detection of cocaine was based on a competitive assay. The change of frequency measured after 300s of the binding reaction was used as the signal. The maximum binding of the antibody resulted in a frequency decrease of 35Hz (with an imprecision 3%, n = 3) while the presence of 100pmoll(-1) cocaine decreased the binding by 11%. The limit of detection was consequently below 100pmoll(-1) for cocaine. The total time of one analysis was 15min. This BZE-DADOO-modified sensor was adapted for the detection of organophosphates. BZE-DADOO - a competitive inhibitor - served as binding element for cholinesterase in a competitive assay.
authors.affiliation: Department of Analytical Biochemistry, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Golm, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Halámek
authors.forename: Alexander
authors.initials: A
authors.lastname: Makower
authors.forename: Kristina
authors.initials: K
authors.lastname: Knösche
authors.forename: Petr
authors.initials: P
authors.lastname: Skládal
authors.forename: Frieder W
authors.initials: FW
authors.lastname: Scheller