PQQ-sGDH Bioelectrodes Based on Os-Complex Modified Electrodeposition Polymers and Carbon Nanotubes

Abstract

Graphite electrodes were modified with specifically designed Os-complex modified electrodeposition polymers exhibiting a formal potential of the polymer-bound complex of about 0 to 20 mV (vs. Ag/AgCl/3 M KCl) which is only about 100 mV anodic of the formal potential of pyrroloquinoline quinone (PQQ) in PQQ-dependent glucose dehydrogenase (PQQ-GDH). The efficiency of wiring the polymer-entrapped PQQ-GDH was dependent on the nature of the polymer backbone, the crosslinking with bifunctional crosslinkers and the co-entrapment of multi-walled carbon nanotubes. Due to the limited long-term stability a new polymer synthesis strategy was adapted using the same Os-complex but providing enhanced crosslinking capabilities by introducing epoxide functions at the polymer backbone. Related bioelectrodes showed enhanced glucose-dependent current and a stability of at least 3 days of continuous operation.

Review of Electrochemically Triggered Macromolecular Film Buildup Processes and Their Biomedical Applications

“…In order to improve the electron transfer, osmium functionalized polymers, redox polymers, were co-deposited with several enzymes, such as quinohemoprotein alcohol dehydrogenase, 48 AOX/HRP bi-enzyme system, 52,56 GOX, 54,[58][59] Laccase, [59][60] cellobiose dehydrogenase, 58 pyrroloquinoline quinone-dependent glucose dehydrogenase. 58,[61][62] In this last case, mediated electron transfer is obtained by electron hopping through consecutive oxidation/reduction reactions of osmium moieties ( Figure 5). Recently,…”

“…Generally, direct electron transfer between the enzyme and the electrode is most of the time prevented due to the deeply buried prosthetic group in the enzyme. To improve the electron transfer, osmium functionalized polymers, redox polymers, were codeposited with several enzymes, such as quinohemoprotein alcohol dehydrogenase, AOX/HRP bienzyme system, , GOX, ,, laccase, , cellobiose dehydrogenase and pyrroloquinoline quinone-dependent glucose dehydrogenase. ,, In this last case, mediated electron transfer is obtained by electron hopping through consecutive oxidation/reduction reactions of osmium moieties (Figure ). Recently, Plamper published a review that categorizes the different basic mechanisms for electrochemical switching of redox-active polymers, leading to conformational and solubility changes …”