@article{PengYarmanJetzschmannetal.2016, author = {Peng, Lei and Yarman, Aysu and Jetzschmann, Katharina J. and Jeoung, Jae-Hun and Schad, Daniel and Dobbek, Holger and Wollenberger, Ursula and Scheller, Frieder W.}, title = {Molecularly Imprinted Electropolymer for a Hexameric Heme Protein with Direct Electron Transfer and Peroxide Electrocatalysis}, series = {SENSORS}, volume = {16}, journal = {SENSORS}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s16030272}, pages = {1343 -- 1364}, year = {2016}, abstract = {For the first time a molecularly imprinted polymer (MIP) with direct electron transfer (DET) and bioelectrocatalytic activity of the target protein is presented. Thin films of MIPs for the recognition of a hexameric tyrosine-coordinated heme protein (HTHP) have been prepared by electropolymerization of scopoletin after oriented assembly of HTHP on a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold electrodes. Cavities which should resemble the shape and size of HTHP were formed by template removal. Rebinding of the target protein sums up the recognition by non-covalent interactions between the protein and the MIP with the electrostatic attraction of the protein by the SAM. HTHP bound to the MIP exhibits quasi-reversible DET which is reflected by a pair of well pronounced redox peaks in the cyclic voltammograms (CVs) with a formal potential of -184.4 +/- 13.7 mV vs. Ag/AgCl (1 M KCl) at pH 8.0 and it was able to catalyze the cathodic reduction of peroxide. At saturation the MIP films show a 12-fold higher electroactive surface concentration of HTHP than the non-imprinted polymer (NIP).}, language = {en} } @article{TangWerchmeisterPredaetal.2019, author = {Tang, Jing and Werchmeister, Rebecka Maria Larsen and Preda, Loredana and Huang, Wei and Zheng, Zhiyong and Leimk{\"u}hler, Silke and Wollenberger, Ulla and Xiao, Xinxin and Engelbrekt, Christian and Ulstrup, Jens and Zhang, Jingdong}, title = {Three-dimensional sulfite oxidase bioanodes based on graphene functionalized carbon paper for sulfite/O-2 biofuel cells}, series = {ACS catalysis}, volume = {9}, journal = {ACS catalysis}, number = {7}, publisher = {American Chemical Society}, address = {Washington}, issn = {2155-5435}, doi = {10.1021/acscatal.9b01715}, pages = {6543 -- 6554}, year = {2019}, abstract = {We have developed a three-dimensional (3D) graphene electrode suitable for the immobilization of human sulfite oxidase (hSO), which catalyzes the electrochemical oxidation of sulfite via direct electron transfer (DET). The electrode is fabricated by drop-casting graphene-polyethylenimine (G-P) composites on carbon papers (CPs) precoated with graphene oxide (GO). The negatively charged hSO can be adsorbed electrostatically on the positively charged matrix (G-P) on CP electrodes coated with GO (CPG), with a proper orientation for accelerated DET. Notably, further electrochemical reduction of G-P on CPG electrodes leads to a 9-fold increase of the saturation catalytic current density (j(m)) for sulfite oxidation reaching 24.4 +/- 0.3 mu A to cm(-2), the highest value among reported DET-based hSO bioelectrodes. The increased electron transfer rate plays a dominating role in the enhancement of direct enzymatic current because of the improved electric contact of hSO with the electrode, The optimized hSO bioelectrode shows a significant catalytic rate (k(cat): 25.6 +/- 0.3 s(-1)) and efficiency (k(cat)/K-m: 0.231 +/- 0.003 s(-1) mu M-1) compared to the reported hSO bioelectrodes. The assembly of the hSO bioanode and a commercial platinum biocathode allows the construction of sulfite/O-2 enzymatic biofuel cells (EBFCs) with flowing fuels. The optimized EBFC displays an open-circuit voltage (OCV) of 0.64 +/- 0.01 V and a maximum power density of 61 +/- 6 mu W cm(-2) (122 +/- 12 mW m(-3)) at 30 degrees C, which exceeds the best reported value by more than 6 times.}, language = {en} } @article{JetzschmannTankJagerszkietal.2019, author = {Jetzschmann, Katharina J. and Tank, Steffen and Jagerszki, Gyula and Gyurcsanyi, Robert E. and Wollenberger, Ulla and Scheller, Frieder W.}, title = {Bio-Electrosynthesis of Vectorially Imprinted Polymer Nanofilms for Cytochrome P450cam}, series = {ChemElectroChem}, volume = {6}, journal = {ChemElectroChem}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2196-0216}, doi = {10.1002/celc.201801851}, pages = {1818 -- 1823}, year = {2019}, abstract = {A new approach for synthesizing a vectorially imprinted polymer (VIP) is presented for the microbial cytochrome P450cam enzyme. A surface attached binding motif of a natural reaction partner of the target protein, putidaredoxin (Pdx), is the anchor to the underlying transducer. The 15 amino acid peptide anchor, which stems from the largest continuous amino acid chain within the binding site of Pdx was modified: (i) internal cysteines were replaced by serines to prevent disulfide bond formation; (ii) 2 ethylene glycol units were attached to the N-terminus as a spacer region; and (iii) an N-terminal cysteine was added to allow the immobilization on the gold electrode surface. Immobilization on GCE was achieved via an N-(1-pyrenyl)maleimide (NPM) cross-linker. In this way oriented immobilization of P450cam was accomplished by binding it to a peptide-modified gold or glassy carbon electrode (GCE) prior to the electrosynthesis of a polymer nanofilm around the immobilized target. This VIP nanofilm enabled reversible oriented docking of P450cam as it is indicated by the catalytic oxygen reduction via direct electron transfer between the enzyme and the underlying electrode. Catalysis of oxygen reduction by P450cam bound to the VIP-modified GCE was used to measure rebinding to the VIP. The mild coupling of an oxidoreductase with the electrode may be appropriate for realizing electrode-driven substrate conversion by instable P450 enzymes without the need of NADPH co-factor.}, language = {en} }