title: Microchannel conductivity measurements in microchip for on line monitoring of dephosphorylation rates of organic phosphates using paramagnetic-beads linked alkaline phosphatase.
abstract: This paper presents the use of polymer coated microelectrodes for the realtime conductivity monitoring in a microchannel photoablated through the polymer without contact. Based on this strategy, a small conductometry sensor has been developed to record in time conductivity variation when an enzymatic reaction occurs through the channel. The rate constant determination, k2, for the dephosphorylation of organic phosphate-alkaline phosphatase-superparamagnetic beads complex using chemically different substrates such as adenosine monoesterphosphate, adenosine diphosphate and adenosine triphosphate was taken as an example to demonstrate selectivity and sensivity of the detection scheme. The k2 value measured for each adenosine phosphate decreases from 39 to 30 s(-1) in proportion with the number (3, 2 and 1) of attached phosphate moiety, thus emphasizing the steric hindrance effect on kinetics.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8235, Laboratoire Interfaces et Systèmes Electrochimiques, F-75005 Paris, France.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Kechadi
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7622, Laboratoire Biologie des Semences, 4 Place Jussieu, F-75005 Paris, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Sotta
authors.affiliation: CNRS, UMR 8235, LISE, F-75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR 8235, Laboratoire Interfaces et Systèmes Electrochimiques, F-75005 Paris, France. Electronic address: jean.gamby@upmc.fr.
authors.forename: Jean
authors.initials: J
authors.lastname: Gamby
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry*; D000249:Adenosine Monophosphate / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry*; D000469:Alkaline Phosphatase / Q000737:chemistry*; D003217:Conductometry / Q000379:methods*; D004553:Electric Conductivity; D004800:Enzymes, Immobilized / Q000737:chemistry; D006868:Hydrolysis; D007700:Kinetics; D059346:Magnets; D008839:Microelectrodes; D046210:Microfluidic Analytical Techniques; D010710:Phosphates / Q000032:analysis*; D012996:Solutions
chemical_list: D004800:Enzymes, Immobilized; D010710:Phosphates; D012996:Solutions; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000469:Alkaline Phosphatase
keywords: Admittance; Conductometry; Dephosphorylation; Enzyme; Microchip