CATALYSIS AND MASS-TRANSPORT IN SPATIALLY ORDERED ENZYME ASSEMBLIES ON ELECTRODES

The antigen-antibody immobilization technique has been extended, with glucose oxidase and glassy carbon electrodes as an illustrating exampl e, so as to obtain up to 10 active successive monolayers. A slight mod ification of the technique allows the deactivation of any number of en zyme layers adjacent to the electrode and the deposition on top of the inactivated film of any number of active monolayers. Using these stru ctures and varying the rate of the enzymatic reaction makes it possibl e to observe the interference of mediator mass transport in the contro l of the current responses together with the enzymatic reaction. The f act that the thickness of the enzyme monolayers derived from these exp eriments is the same with all of these film structures demonstrates th eir high degree of spatial order. The value thus found, 470 Angstrom, as well as the value of mediator partition coefficients close to one a nd of the diffusion coefficients close to their value in solution indi cate the low compactness of the enzyme films. The study also provides a starting point for modulating layer by layer the activity of the enz yme film.