A kinetic study of an amperometric enzyme electrode based on immobilised cytochrome C peroxidase

Electrochemical immobilization of enzymes. 3. Immobilization of glucose oxidase in thin films of electrochemically polymerized phenols

“…In order to allow adsorption of the enzyme onto the electrode surface, vide infra, the electrode was allowed to stand at open circuit in the deposition solution for 15 min before commencing potential cycling. After the deposition of the film the electrode was washed by rotating at 9 Hz in the background buffer for 15 min to remove any weakly adsorbed enzyme. The electrode was then transferred to a cell containing a measured volume of the buffer solution presaturated with oxygen at the desired concentration.…”

“…Furthermore we assume that there is no B in the bulk solution. This problem is then a special case of the more general problem of coupled diffusion and reaction in an immobilized enzyme layer (9,32,33). If we assume that the polymer film is sufficiently thin that there is no concentration polarization of either S or A within the film, then, in the steady state, we can write .…”

“…The immobilization of enzymes at electrode surfaces has been much used to construct both amperometric and potentiometric enzyme electrodes (4). Many of these have used conventional immobilization techniques to localize the enzyme at the electrode surface; examples include the physical entrapment of the enzyme behind a dialysis membrane (5,6), the covalent attachment of the enzyme to the electrode surface (7,8) or to a polymeric support (9), or the cross-linking of the enzyme in a protein matrix using glutaraldehyde (10,11). Frequently, these approaches have been combined with the use of a discrete macroscopic membrane to reduce electrode fouling and to alleviate problems of interference caused by electroactive species present in the sample (12).…”

Evidence for the functional mechanism of a polypyrrole glucose oxidase electrode

“…By using equimolar concentrations of apo-GOD and native GOD in the initial growth solution, it is very likely that the amount of active GOD entrapped within the film was also halved, since the apo and the native forms of the enzymes would have been incorporated into the Ppy films in equal amounts. It is interesting to note from these experiments that, by reducing the amount of active en- reported [3,4,8], that when there is a reaction layer at the outside edge of a membrane or a film, the amperometric response is proportional to the square root of the enzyme concentration. Y GOD alone gave no response on exposure to glucose solutions over the range of 1 to 30 mmol dm-3 ( Figure 3 d ) ) .…”

Modified Electrodes with Synthetic Biocatalytic Membranes

“…This required immobilization of biologically active molecules or clusters on the electrode surfaces. Studies show that immobilization of an enzyme by physical entrapment behind a dialysis membrane (6, 7), by covalent attachment to an electrode surface (8, 9), by polymeric support (10), or by cross‐linking in a protein matrix (11) can increase the rigidity of the enzyme molecule, consequently improving its stability.…”