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 example, so as to obtain up to 10 active successive monolayers. A slight modification of the technique allows the deactivation of any number of enzyme layers adjacent to the electrode and the deposition on top of the inactivated film of any number of active monolayers. Using these structures and varying the rate of the enzymatic reaction makes it possible to observe the interference of mediator mass transport in the control of the current responses together with the enzymatic reaction. The fact that the thickness of the enzyme monolayers derived from these experiments is the same with all of these film structures demonstrates their high degree of spatial order. The value thus found, 470 Angstrom, as well as the value of mediator partition coefficients close to one and of the diffusion coefficients close to their value in solution indicate the low compactness of the enzyme films. The study also provides a starting point for modulating layer by layer the activity of the enzyme film.