@article{Yarman2018, author = {Yarman, Aysu}, title = {Electrosynthesized Molecularly Imprinted Polymer for Laccase Using the Inactivated Enzyme as the Target}, series = {Bulletin of the Korean chemical society}, volume = {39}, journal = {Bulletin of the Korean chemical society}, number = {4}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1229-5949}, doi = {10.1002/bkcs.11413}, pages = {483 -- 488}, year = {2018}, abstract = {The first molecularly imprinted polymer (MIP) for the recognition of the copper-enzyme laccase was successfully prepared by electropolymerizing scopoletin in the presence of alkaline-inactivated enzyme. Laccase-MIP and the control polymer without laccase (nonimprinted polymer, NIP) were characterized by voltammetry using the redox marker ferricyanide. After electropolymerization, the signals for ferricyanide for both the MIP and the NIP were almost completely suppressed and increased after removal of the target from the polymer layer. Rebinding of both inactivated and active laccase decreased the ferricyanide peak currents to almost equal extent. The relative decrease of signal suppression approached saturation above 10 nM. Furthermore, the surface activity of rebound laccase toward the oxidation of catechol was investigated. The surface activity approached saturation above 10 nM, a value close to the value of the measurements with ferricyanide. Interaction of NIP with laccase brought about a six times smaller signal of catechol oxidation.}, language = {en} } @article{JetzschmannYarmanRustametal.2018, author = {Jetzschmann, Katharina J. and Yarman, Aysu and Rustam, L. and Kielb, P. and Urlacher, V. B. and Fischer, A. and Weidinger, I. M. and Wollenberger, Ulla and Scheller, Frieder W.}, title = {Molecular LEGO by domain-imprinting of cytochrome P450 BM3}, series = {Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces}, volume = {164}, journal = {Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0927-7765}, doi = {10.1016/j.colsurfb.2018.01.047}, pages = {240 -- 246}, year = {2018}, abstract = {Hypothesis: Electrosynthesis of the MIP nano-film after binding of the separated domains or holocytochrome BM3 via an engineered anchor should result in domain-specific cavities in the polymer layer. Experiments: Both the two domains and the holo P450 BM3 have been bound prior polymer deposition via a N-terminal engineered his6-anchor to the electrode surface. Each step of MIP preparation was characterized by cyclic voltammetry of the redox-marker ferricyanide. Rebinding after template removal was evaluated by quantifying the suppression of the diffusive permeability of the signal for ferricyanide and by the NADH-dependent reduction of cytochrome c by the reductase domain (BMR). Findings: The working hypothesis is verified by the discrimination of the two domains by the respective MIPs: The holoenzyme P450 BM3 was ca. 5.5 times more effectively recognized by the film imprinted with the oxidase domain (BMO) as compared to the BMR-MIP or the non-imprinted polymer (NIP). Obviously, a cavity is formed during the imprinting process around the hiss-tag-anchored BMR which cannot accommodate the broader BMO or the P450 BM3. The affinity of the MIP towards P450 BM3 is comparable with that to the monomer in solution. The hiss-tagged P450 BM3 binds (30 percent) stronger which shows the additive effect of the interaction with the MIP and the binding to the electrode.}, language = {en} } @article{Yarman2017, author = {Yarman, Aysu}, title = {Development of a molecularly imprinted polymer-based electrochemical sensor for tyrosinase}, series = {Turkish journal of chemistry}, volume = {42}, journal = {Turkish journal of chemistry}, number = {2}, publisher = {T{\"u}rkiye Bilimsel ve Teknik Ara{\c{s}}t{\i}rma Kurumu}, address = {Ankara}, issn = {1300-0527}, doi = {10.3906/kim-1708-68}, pages = {346 -- 354}, year = {2017}, abstract = {For the first time a molecularly imprinted polymer (MIP)-based sensor for tyrosinase is described. This sensor is based on the electropolymerization of scopoletin or o-phenylenediamine in the presence of tyrosinase from mushrooms, which has a high homology to the human enzyme. The template was removed either by treatment with proteinase Kor by alkaline treatment. The measuring signal was generated either by measuring the formation of a product by the target enzyme or by evaluation of the permeability of the redox marker ferricyanide. The o-phenylenediamine-based MIP sensor has a linear measuring range up to 50 nM of tyrosinase with a limit of detection of 3.97 nM (R 2 = 0.994) and shows good discrimination towards other proteins, e.g., bovine serum albumin and cytochrome c.}, language = {en} } @article{YarmanScheller2016, author = {Yarman, Aysu and Scheller, Frieder W.}, title = {MIP-esterase/Tyrosinase Combinations for Paracetamol and Phenacetin}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {28}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1040-0397}, doi = {10.1002/elan.201600042}, pages = {2222 -- 2227}, year = {2016}, abstract = {A new electrochemical MIP sensor for the most frequently used drug paracetamol (PAR) was prepared by electropolymerization of mixtures containing the template molecule and the functional monomers ophenylenediamine, resorcinol and aniline. The imprinting factor of 12 reflects the effective target binding to the MIP as compared with the non-imprinted electropolymer. Combination of the MIP with a nonspecific esterase allows the measurement of phenacetin - another analgesic drug. In the second approach the PAR containing sample solution was pretreated with tyrosinase in order to prevent electrochemical interferences by ascorbic acid and uric acid. Interference-free indication at a very low electrode potential without fouling of the electrode surface was achieved with the o-phenylenediamine: resorcinol-based MIP.}, language = {en} } @article{SchellerYarmanBachmannetal.2014, author = {Scheller, Frieder W. and Yarman, Aysu and Bachmann, Till and Hirsch, Thomas and Kubick, Stefan and Renneberg, Reinhard and Schumacher, Soeren and Wollenberger, Ursula and Teller, Carsten and Bier, Frank Fabian}, title = {Future of biosensors: a personal view}, series = {Advances in biochemical engineering, biotechnology}, volume = {140}, journal = {Advances in biochemical engineering, biotechnology}, editor = {Gu, MB and Kim, HS}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-642-54143-8; 978-3-642-54142-1}, issn = {0724-6145}, doi = {10.1007/10_2013_251}, pages = {1 -- 28}, year = {2014}, abstract = {Biosensors representing the technological counterpart of living senses have found routine application in amperometric enzyme electrodes for decentralized blood glucose measurement, interaction analysis by surface plasmon resonance in drug development, and to some extent DNA chips for expression analysis and enzyme polymorphisms. These technologies have already reached a highly advanced level and need minor improvement at most. The dream of the "100-dollar' personal genome may come true in the next few years provided that the technological hurdles of nanopore technology or of polymerase-based single molecule sequencing can be overcome. Tailor-made recognition elements for biosensors including membrane-bound enzymes and receptors will be prepared by cell-free protein synthesis. As alternatives for biological recognition elements, molecularly imprinted polymers (MIPs) have been created. They have the potential to substitute antibodies in biosensors and biochips for the measurement of low-molecular-weight substances, proteins, viruses, and living cells. They are more stable than proteins and can be produced in large amounts by chemical synthesis. Integration of nanomaterials, especially of graphene, could lead to new miniaturized biosensors with high sensitivity and ultrafast response. In the future individual therapy will include genetic profiling of isoenzymes and polymorphic forms of drug-metabolizing enzymes especially of the cytochrome P450 family. For defining the pharmacokinetics including the clearance of a given genotype enzyme electrodes will be a useful tool. For decentralized online patient control or the integration into everyday "consumables' such as drinking water, foods, hygienic articles, clothing, or for control of air conditioners in buildings and cars and swimming pools, a new generation of "autonomous' biosensors will emerge.}, language = {en} }