High-performance amperometric biosensors and biofuel cell based on chitosan-strengthened cast thin films of chemically synthesized catecholamine polymers with glucose oxidase effectively entrapped

Rapid oxidation of dopamine (DA) or l-noradrenaline (NA) by K3Fe(CN)6 yields poly(DA) (PDAC) or poly(NA) (PNAC) with glucose oxidase (GOx) effectively entrapped, and such an enzyme-entrapped catecholamine polymer is cast on an Au electrode followed by chitosan (CS) strengthening for biosensing and fabrication of a biofuel cell (BFC). The optimized glucose biosensor of CS/PDAC–GOx/Au displays an extremely high sensitivity up to 135 μA mM−1 cm–2, a very low limit of detection of 0.07 μM, a response time of <3 s, good suppression of interferents, striking thermostability (lifetime of 3 weeks at 60 °C and over 2 months at 30 °C), and high resistance to urea denaturation. The biosensor also works well in the second generation biosensing mode with p-benzoquinone (BQ) or ferrocene monocarboxylic acid (Fc) as an artificial mediator, with greatly broadened linear detection ranges (2.0 μM–48.0 mM for BQ and 2.0 μM–16.0 mM for Fc) and up to mA cm−2-scale glucose-saturated current density. The good permeability of artificial mediators across the enzyme film enables the quantification of the surface concentration of immobilized GOx on the basis of a reported kinetic model, and UV–Vis spectrophotometry is used to measure the enzymatic activity, revealing high enzymatic activity/load at CS/PDAC–GOx/Au. A BFC is also successfully fabricated with a bioanode of CS/PDAC–GOx/Au in phosphate buffer solution containing 100 mM glucose and 4.0 mM BQ and a carbon cathode in Nafion-membrane-isolated acidic KMnO4, and its maximum power density of 1.62 mW cm−2 is superior to those of most BFC hitherto reported.