@article{SarauliBorowskiPetersetal.2016, author = {Sarauli, David and Borowski, Anja and Peters, Kristina and Schulz, Burkhard and Fattakhova-Rohlfing, Dina and Leimk{\"u}hler, Silke and Lisdat, Fred}, title = {Investigation of the pH-Dependent Impact of Sulfonated Polyaniline on Bioelectrocatalytic Activity of Xanthine Dehydrogenase}, series = {ACS catalysis}, volume = {6}, journal = {ACS catalysis}, publisher = {American Chemical Society}, address = {Washington}, issn = {2155-5435}, doi = {10.1021/acscatal.6b02011}, pages = {7152 -- 7159}, year = {2016}, abstract = {We report on the pH-dependent bioelectrocatalytic activity of the redox enzyme xanthine dehydrogenase (XDH) in the presence of sulfonated polyaniline PMSA1 (poly(2-methoxyaniline-5-sulfonic acid)-co-aniline). Ultraviolet-visible (UV-vis) spectroscopic measurements with both components in solution reveal electron transfer from the hypoxanthine (HX)-reduced enzyme to the polymer. The enzyme shows bioelectrocatalytic activity on indium tin oxide (ITO) electrodes, when the polymer is present. Depending on solution pH, different processes can be identified. It can be demonstrated that not only product-based communication with the electrode but also efficient polymer-supported bioelectrocatalysis occur. Interestingly, substrate dependent catalytic currents can be obtained in acidic and neutral solutions, although the highest activity of XDH with natural reaction partners is in the alkaline region. Furthermore, operation of the enzyme electrode without addition of the natural cofactor of XDH is feasible. Finally, macroporous ITO electrodes have been used as an immobilization platform for the fabrication of HX-sensitive electrodes. The study shows that the efficient polymer/enzyme interaction can be advantageously combined with the open structure of an electrode material of controlled pore size, resulting in good processability, stability, and defined signal transfer in the presence of a substrate.}, language = {en} } @article{SarauliXuDietzeletal.2012, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Stiba, Konstanze and Leimk{\"u}hler, Silke and Schulz, Burkhard and Lisdat, Fred}, title = {Thin films of substituted polyanilines interactions with biomolecular systems}, series = {Soft matter}, volume = {8}, journal = {Soft matter}, number = {14}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c2sm07261k}, pages = {3848 -- 3855}, year = {2012}, abstract = {We use substituted polyanilines for the construction of new polymer electrodes for interaction studies with the redox protein cytochrome c (cyt c) and the enzyme sulfite oxidase (SO). For these purposes four different polyaniline copolymers are chemically synthesized. Three of them are copolymers, containing 2-methoxyaniline-5-sulfonic acid with variable ratios of aniline; the fourth copolymer consists of 3-amino-benzoic acid and aniline. The results show that all polymers are suitable for being immobilized as thin stable films on gold wire and indium tin oxide (ITO) electrode surfaces from DMSO solution. This can be demonstrated by cyclic voltammetry and UV-Vis spectroscopy measurements. Moreover, cyt c can be electrochemically detected not only in solution, but also immobilized on top of the polymer films. Furthermore, the appearance of a significant catalytic current has been demonstrated for the sulfonated polyanilines, when the polymer-coated protein electrode is being measured upon addition of sulfite oxidase, confirming the establishment of a bioanalytical signal chain. Best results have been obtained for the polymer with highest sulfonation grade. The redox switching of the polymer by the enzymatic reaction can also be analyzed by following the spectral properties of the polymer electrode.}, language = {en} }