@misc{DrexlerShishkanovaLangeetal., author = {Drexler, Christoph and Shishkanova, Tatiana V. and Lange, Christoph and Danilov, Sergey N. and Weiss, Dieter and Ganichev, Sergey D. and Mirsky, Vladimir M.}, title = {Terahertz split-ring metamaterials as transducers for chemical sensors based on conducting polymers: a feasibility study with sensing of acidic and basic gases using polyaniline chemosensitive layer}, series = {Microchimica Acta}, volume = {181}, journal = {Microchimica Acta}, issn = {1436-5073}, doi = {10.5283/epub.31493}, pages = {1857 -- 1862}, abstract = {We report on the first application of terahertz metamaterials acting as transducers for chemical sensors based on conducting polymers. In our feasibility study aimed at sensing of gaseous hydrochloric and ammonia, a two-dimensional sensor metamaterial consisting of an array of split-ring resonators on the surface of undoped silicon wafer was prepared. The surface of the resonator was coated with a 150-μm layer of polyaniline. Binding of hydrogen chloride to polyaniline leads to distinct changes in the resonance frequency of the metamaterial. Measurements can be performed both in the reflection and transmission mode. A numerical simulation of the response revealed an increase of both the real and the imaginary components of the dielectric function of the polyaniline film. These changes are attributed to the transition from emaraldine base to emeraldine salt. The results demonstrate a new approach for formation of highly sensitive transducers for chemical sensors.}, language = {en} } @misc{DelaneyZiminRahmetal., author = {Delaney, Tetyana L. and Zimin, Denys and Rahm, Michael and Weiss, Dieter and Wolfbeis, Otto S. and Mirsky, Vladimir M.}, title = {Capacitive detection in ultrathin chemosensors prepared by molecularly imprinted grafting photopolymerization}, series = {Analytical Chemistry}, volume = {79}, journal = {Analytical Chemistry}, number = {8}, issn = {0003-2700}, doi = {10.1021/ac062143v}, pages = {3220 -- 3225}, abstract = {The usual applications of capacitive detection in chemo- and biosensors are based on changes in effective thickness of insulating layers due to adsorption of analyte onto receptors. Ultrathin chemosensors based on molecularly imprinted polymerization enable a realization of another capacitive approach that exploits changes in electrical capacitance due to modification of the dielectric constant of the polymer. Such chemosensors were prepared by photografted molecularly imprinted polymerization on the surface of gold electrodes. An adsorbed layer of hydrophobic photoinitiator (benzophenone) provided grafted polymerization on the surface of the alkanethiol-modified gold electrode. The chemosensors were characterized by cyclic voltammetry, impedance spectroscopy, and scanning electron and atomic force microscopy. Binding of analyte was detected by measurements of electrical capacitance. The results indicate a decrease of the dielectric constant of the polymer layer due to analyte binding up to 20\%.}, language = {en} } @misc{HirschZharnikovShaporenkoetal., author = {Hirsch, Thomas and Zharnikov, Michael and Shaporenko, Andrey and Stahl, Joachim and Weiss, Dieter and Wolfbeis, Otto S. and Mirsky, Vladimir M.}, title = {Size-controlled electrochemical synthesis of metallic nanoparticles on molecular templates}, series = {Angewandte Chemie International Edition}, volume = {44}, journal = {Angewandte Chemie International Edition}, number = {41}, issn = {1521-3773}, doi = {10.1002/anie.200500912}, pages = {6775 -- 6778}, abstract = {Reduction on the spot: Planarly adsorbed thiolated porphyrin molecules (purple) incorporated in an insulating alkanethiol monolayer (blue) function as nanoelectrodes for the local reduction of metals (gray). This approach was applied for the in situ synthesis of nanoparticles of a predetermined size.}, language = {en} } @misc{HaoRahmWeissetal., author = {Hao, Qingli and Rahm, Michael and Weiss, Dieter and Mirsky, Vladimir M.}, title = {Morphology of electropolymerized poly (N-methylaniline) films}, series = {Microchimica Acta}, volume = {143}, journal = {Microchimica Acta}, number = {2}, issn = {0026-3672}, doi = {10.1007/s00604-003-0063-8}, pages = {147 -- 153}, abstract = {The influence of polymerization conditionson the morphology of thin films of poly-(N-methylani-line) (PNMA) was studied. The films were prepared byelectropolymerization on gold and platinum electrodesand studied by optical and electron microscopy. It wasdemonstrated that the film morphology does notdepend on the polymerization rate or on the electrodemetal.However,itissensitivetothekindofcounterionofPNMA.Thepolymerscontainingacetate orchloridedo not form stable films. Polymer films containingphosphate or sulfate display inhomogeneous struc-tures. A formation of sprouts and ''nanotubes'' wasobserved for PNMA sulfate. The films formed byPNMA perchlorate are smooth and transparent(glass-likestructure).Asublayerof4-aminothiophenolincreases the adhesion of polymers to the gold surface.}, language = {en} }