Wiring efficiency in layer-by-layer (PAA-Os)n(GOx)n self-assembled glucose biosensors

EJ. CALVO; C DANILOWICZ; E FORZANI; A WOLOSIUK; MARCELO JAVIER OTERO

San Francisco

Congreso; Joint International Meeting of ISE and the Electrochemical Society; 2001

Electrochemical Society

Supramolecular structures comprised of glucose oxidase and a poly-cation based on Os complex derivatised poly(allylamine) (PAA-Os) have been constructed by alternate electrostatic adsorption in a layer-by-layer self-assembly process. The resulting modified electrodes were tested as reagentless glucose biosensors. The enzyme kinetic parameters and the surface concentration of ¡§wired¡¨ enzyme (ƒ·enz(wired)) have been obtained by analysis of the catalytic current dependence on glucose concentrations: k[Os], assuming kcat and KM values for the ping-pong mechanism of glucose oxidase. The osmium volumen concentration has been obtained by integration of the redox charge in the absence of glucose and the ellipsometric thickness of these multilayers. The total enzyme surface concentration was measured with a quartz crystal microbalance in each adsoption step. The amperometric response of the reagentless biosensors has been analysed in terms of the fraction of ¡§wired¡¨ enzyme and the bimolecular rate constant for FADH2 oxidation by the redox polymer for the different multilayers.