Figure 3.

(A) An enzyme physically entrapped in a polymer operating as a redox matrix providing the enzyme electrical wiring by electron hopping through redox sites finally reaching an electrode conducting support. The redox-mediator sites are represented with [Os-(2,2′-bipyridine)₂]^2+/3+-complex pendant at poly(vinylpyridine) matrix. (B) A similar system where the enzyme is covalently bound to the redox polymer. The systems have been pioneered by Prof. Adam Heller. They are exemplified with an enzyme oxidizing a substrate and generating anodic current mediated by the redox polymer irrespective of the enzyme orientation. (C) A cyclic voltammogram, showing a 400 μA cm⁻² glucose diffusion limited current density reached at 40 mM glucose concentration with the wired-enzyme shown schematically in (B). The scan rate is 5 mV/s. (D) Prof. Adam Heller – the pioneer in the enzyme wiring according to many various approaches, particularly including systems exemplified in (A,B). (Part C was adopted from [44]; (D) the photo was adopted from Wikipedia, public domain).