Glucose oxidase ferrocene tethered

A further approach to electrically wire redox enzymes by means of supramolecular structures that include CNTs as conductive elements involved the wrapping of CNTs with water-soluble polymers, for example, polyethylene imine or polyacrylic acid.54 The polymer coating enhanced the solubility of the CNTs in aqueous media, and facilitated the covalent linkage of the enzymes to the functionalized CNTs (Fig. 12.9c). The polyethylene imine-coated CNTs were covalently modified with electroactive ferrocene units, and the enzyme glucose oxidase (GOx) was covalently linked to the polymer coating. The ferrocene relay units were electrically contacted with the electrode by means of the CNTs, and the oxidized relay mediated the electron transfer from the enzyme-active center to the electrode, a process that activated the bioelectrocatalytic functions of GOx. Similar results were observed upon tethering the ferrocene units to polyacrylic acid-coated CNTs, and the covalent attachment of GOx to the modifying polymer. 

Scheme 11 Photochemical control of electrical contact between a ferrocene-tethered glucose oxidase and the electrode using a thiolated nitrospiropyran as a command interface.

Figure 7. Cyclic voltammograms of a bare Au electrode in the presence of glucose oxidase with ferrocene units covalently tethered to lysine residues (cf. Figure 5D)...

The association of the DNP-Ab to the antigen-monolayer-functionalized electrode leads to the electrical insulation of the electrode support and to the introduction of an electron barrier at the electrode surface. Thus, in the presence of an electrically wired enzyme (e.g., ferrocene-tethered glucose oxidase), the bioelectrocatalytic current is inhibited upon the formation of... 

The electrostatic control of the electrical contact between redox-proteins and electrodes by means of command interfaces was further demonstrated by the photochemical switching of the bioelectrocatalytic properties of glucose oxidase (Figure 7.22). Ferrocene units were tethered to the protein backbone of glucose oxidase to yield an electrically wired enzyme that is activated for the bioelectrocatalyzed oxidation of glucose. The enzyme is negatively charged at neutral pH values (pIc,o 4.2 ) and, hence, could be... 

---