Redox electrodeposition polymers: adaptation of the redox potential of polymer-bound Os complexes for bioanalytical applications

Abstract

The design of polymers carrying suitable ligands for coordinating Os complexes in ligand exchange reactions against labile chloro ligands is a strategy for the synthesis of redox polymers with bound Os centers which exhibit a wide variation in their redox potential. This strategy is applied to polymers with an additional variation of the properties of the polymer backbone with respect to pH-dependent solubility, monomer composition, hydrophilicity etc. A library of Os-complex-modified electrodeposition polymers was synthesized and initially tested with respect to their electron-transfer ability in combination with enzymes such as glucose oxidase, cellobiose dehydrogenase, and PQQ-dependent glucose dehydrogenase entrapped during the pH-induced deposition process. The different polymer-bound Os complexes in a library containing 50 different redox polymers allowed the statistical evaluation of the impact of an individual ligand to the overall redox potential of an Os complex. Using a simple linear regression algorithm prediction of the redox potential of Os complexes becomes feasible. Thus, a redox polymer can now be designed to optimally interact in electron-transfer reactions with a selected enzyme.

The Thermophilic CotA Laccase from Bacillus subtilis: Bioelectrocatalytic Evaluation of O2 Reduction in the Direct and Mediated Electron Transfer Regime

“…A second approach to immobilize the enzyme on the electrode surface with a loading exceeding one monolayer is the entrapment of enzymes within an Os-complex modified electrodeposition polymer [33,40,41]. Anodic acrylate-based redox polymers containing carboxylic groups can be immobilized together with enzymes on electrodes by modulation of the pH-value in close proximity to the surface.…”

“…Osmium-bis-N,N-(2,2'-bipyridil)-dichloride, 2-(2-pyridin-2-yl-1H-imidazol-1-yl)ethyl acrylate and 4-pyridyl-propyl methacrylate were synthesized following previously described procedures [29][30][31]. Syntheses of Os-complex modified polymers were carried out by a free-radical polymerization followed by a ligand-exchange reaction between Osmium-bis-(2,2'-bipyridil)-dichloride and functional groups of the copolymer similar to [32,33].…”

Electron Transfer between Genetically Modified Hansenula polymorpha Yeast Cells and Electrode Surfaces via Os-complex modified Redox Polymers

“…The realization of the required locally high concentration of Os complexes became possible by means of a customized synthesis of the Os-complex modified redox polymers. [44][45] The ability of four different sensor architectures, namely, 1) genetically modified yeast cells integrated into an Os-complex modified redox polymer (GM-HP-OsRP), 2) wild-type yeast cells integrated into an Os-complex modified redox polymer (WT-HP-OsRP), 3) genetically modified yeast cells entrapped behind a dialysis membrane (GM-HP-DM), and iv) wild-type yeast cells entrapped behind a dialysis membrane (WT-HP-DM), was investigated with respect to their response to an exposure to l-lactate. Chronoamperometric measurements were performed with stepwise increments of the l-lactate concentration at a working potential above the formal potential of the polymer-bound Os complexes.…”

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

“…Despite the fact that a wide range of redox potentials was achieved by changing the coordination sphere of the polymer-bound Os-complexes electrode modification was only possible by drop-or dip-coating. Electrochemically induced electrode modification procedures such as deposition of redox-mediator modified conducting polymers [19][20][21] or Os-complex modified electrodeposition paints (EDPs) [22][23][24][25][26] have inherent advantages due to the improved control and reproducibility of the formed polymer layer. Os-complex modified EDPs have been successfully applied for the construction of cellobiose dehydrogenase-based bioanodes 27,28 and laccase-based biocathodes.…”