@article{MikatFrancoRegensteinetal.2000, author = {Mikat, J{\"u}rgen E. R. and Franco, Olga and Regenstein, Wolfgang and Reck, G{\"u}nter and Knochenhauer, Gerald and Schulz, Burkhard and Orgzall, Ingo}, title = {1,3,4-oxadiazole crystals under high pressure-phase transitions and properties}, year = {2000}, language = {en} } @article{SarauliPetersXuetal.2014, author = {Sarauli, David and Peters, Kristina and Xu, Chenggang and Schulz, Burkhard and Fattakhova-Rohlfing, Dina and Lisdat, Fred}, title = {3D-Electrode architectures for enhanced direct bioelectrocatalysis of pyrroloquinoline quinone-dependent glucose dehydrogenase}, series = {ACS applied materials \& interfaces}, volume = {6}, journal = {ACS applied materials \& interfaces}, number = {20}, publisher = {American Chemical Society}, address = {Washington}, issn = {1944-8244}, doi = {10.1021/am5046026}, pages = {17887 -- 17893}, year = {2014}, abstract = {We report on the fabrication of a complex electrode architecture for efficient direct bioelectrocatalysis. In the developed procedure, the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase entrapped in a sulfonated polyaniline [poly(2-methoxyaniline-5-sulfonic acid)-co-aniline] was immobilized on macroporous indium tin oxide (macroITO) electrodes. The use of the 3D-conducting scaffold with a large surface area in combination with the conductive polymer enables immobilization of large amounts of enzyme and its efficient communication with the electrode, leading to enhanced direct bioelectrocatalysis. In the presence of glucose, the fabricated bioelectrodes show an exceptionally high direct bioelectrocatalytical response without any additional mediator. The catalytic current is increased more than 200-fold compared to planar ITO electrodes. Together with a high long-term stability (the current response is maintained for >90\% of the initial value even after 2 weeks of storage), the transparent 3D macroITO structure with a conductive polymer represents a valuable basis for the construction of highly efficient bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.}, language = {en} } @misc{SarauliXuDietzeletal.2014, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-98744}, year = {2014}, abstract = {A feasible approach to construct multilayer films of sulfonated polyanilines - PMSA1 and PABMSA1 - containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60\% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.}, language = {en} } @article{SarauliXuDietzeletal.2014, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase: tunable direct bioelectrocatalysis}, series = {Journal of materials chemistry : B, Materials for biology and medicine}, volume = {2}, journal = {Journal of materials chemistry : B, Materials for biology and medicine}, number = {21}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-750X}, doi = {10.1039/c4tb00336e}, pages = {3196 -- 3203}, year = {2014}, abstract = {A feasible approach to construct multilayer films of sulfonated polyanilines - PMSA1 and PABMSA1 containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60\% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.}, language = {en} } @article{RottkeSchulzRichauetal.2016, author = {Rottke, Falko O. and Schulz, Burkhard and Richau, Klaus and Kratz, Karl and Lendlein, Andreas}, title = {An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers}, series = {Beilstein journal of nanotechnology}, volume = {7}, journal = {Beilstein journal of nanotechnology}, publisher = {Beilstein-Institut zur F{\~A}\Prderung der Chemischen Wissenschaften}, address = {Frankfurt, Main}, issn = {2190-4286}, doi = {10.3762/bjnano.7.107}, pages = {1156 -- 1165}, year = {2016}, abstract = {The applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air-water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(omega-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness, R-q. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified.}, language = {en} } @article{BauerSchulzBrehmeretal.1995, author = {Bauer, J. and Schulz, Burkhard and Brehmer, Ludwig and B{\"o}tcher, M. and Jagdhold, U. and H{\"o}ppner, K. and Kulesch, A. and Dietzel, Birgit}, title = {Anwendung von Langmuir-Blodgett-Schichten als Resist f{\"u}r die Niederspannungs-Elektronenstrahl-Lithografie}, year = {1995}, language = {de} } @article{SchulzBrumaBrehmer1997, author = {Schulz, Burkhard and Bruma, Maria and Brehmer, Ludwig}, title = {Aromatic poly(1,3,4-oxadiazole)s as advanced materials}, year = {1997}, abstract = {Poly(1,3,4-oxadiazole)s have been the focus of considerable interest with regard to the- production of high- performance materials, particularly owing to their high thermal stability in oxidative atmosphere and specific properties determined by the structure of 1,3,4-oxadiazole ring, which, from the spectral and electronic points of view, is similar to a p-phenylene structure.[1] Besides their excellent resistance to high temperature, polyoxadiazoles have many desirable characteristics, such as good hydrolytic stability, high glass transition temperatures, low dielectric constants, and tough mechanical properties. Some polyoxadiazoles have semiconductive properties, other structures can be electrochemically doped and thus made conductive, and other have liquid-crystalline properties, which make them very attractive for a wide range of high-performance applications. They exhibit excellent fiber- and film-forming capabilities, thus being considered for use as heat-resistant reinforcing fibers for advanced composite materials, highly resistant fabrics for the filtration of hot gases, special membranes for gas separation or reverse osmosis, precursors for highly oriented graphite fibers, films, and blocks to be used in the construction of electronic instruments based on X-rays, neutron beams, or a-particles, or in the construction of nuclear reactor walls. Since they were first reported in 1961,[2] a wide variety of polymers containing 1,3,4-oxadiazole rings have been synthesized, and their preparation, characterization, and physico-mechanical properties have been periodically reviewed .[3-8] This article will present a general overview of this class of polymers and will refer to the work carried out by different researchers in the last ten years with the emphasis on the potential uses of such polymers as advanced materials.}, language = {en} } @article{BrumaSchulzKoepnicketal.1998, author = {Bruma, Maria and Schulz, Burkhard and K{\"o}pnick, Thomas and Stiller, Burkhard and Hamciuc, Elena and Mercer, Frank W. and Cassidy, Peter}, title = {Aromatic polyamides with hexafluoroisopropylidene groups and study of the thin}, year = {1998}, language = {en} } @article{SchulzDietzelOrgzalletal.2009, author = {Schulz, Burkhard and Dietzel, Birgit and Orgzall, Ingo and Diez, Isabel and Xu, Chenggang}, title = {Aspects of morphology control during the oxidative synthesis of electrically conducting polymers}, issn = {0954-0083}, doi = {10.1177/0954008309339933}, year = {2009}, abstract = {The formation of micro- and nanostructures during the oxidative polymerization of polypyrrole and polyaniline is investigated using different sulfonic acid dopants. Rod- or tube-like structures are found in polypyrrole as well as in polyaniline without addition of further compounds to the initial reaction mixture of monomer, dopant and oxidant. In these cases, always a crystalline precursor complex composed of a dopand molecule and the pure monomer (aniline) or a trimeric moiety (pyrrole) serves as in-situ template. In most cases the surface of the growing polymer is covered by secondary structures with much smaller sizes so that a hierarchical order of structures at different length scales results. Corresponding model considerations for the polymerization process are outlined. Additionally, unusual structures like platelets, frames, rings, or ribbons are observed in the polypyrrole synthesis in the presence of fluorosurfactants.}, language = {en} } @article{SchulzStillerZetzscheetal.1995, author = {Schulz, Burkhard and Stiller, Burkhard and Zetzsche, Thomas and Knochenhauer, Gerald and Dietel, Reinhard and Brehmer, Ludwig}, title = {Characterization of 2,5-di(p-tolyl-1,3,4- oxadiazole) crystals by IR-spectroscopy and atomic force microscopy}, year = {1995}, language = {en} } @article{SchulzStillerZetzscheetal.1997, author = {Schulz, Burkhard and Stiller, Burkhard and Zetzsche, Thomas and Knochenhauer, Gerald and Brehmer, Ludwig}, title = {Characterization of crystals based on 1,3,4-oxadiazoles by atomic force microscopy}, year = {1997}, abstract = {The surface structures of crystals based on aromatic oxadiazoles were investigated by AFM. The crystal structure for 2,5-di(p-tolyl)-1,3,4-oxadiazole (DTO) differs from that of 2,5-di (4-methoxycarbonyl-phenyl)-1,3,4- oxadiazole (DMPO). In DMPO all molecules show parallel orientation to the surface in such a way that the surface is formed as well as by the nitrogen atoms of the heterocyclic rings and the methyl groups of the ester substituents. By contrast, the oxadiazole molecules in DTO crystals are oriented perpendicular to the crystal surface. The experimental data are interpreted by molecular modelling. It is shown that there is a difference between molecular structure of the surface, as detected by AFM, and the bulk structure determined by X-ray diffraction.}, language = {en} } @article{SchoeneSchulzRichauetal.2014, author = {Sch{\"o}ne, Anne-Christin and Schulz, Burkhard and Richau, Klaus and Kratz, Karl and Lendlein, Andreas}, title = {Characterization of Langmuir films prepared from copolyesterurethanes based on oligo(omega-pentadecalactone) and oligo(epsilon-caprolactone)segments}, series = {Macromolecular chemistry and physics}, volume = {215}, journal = {Macromolecular chemistry and physics}, number = {24}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1352}, doi = {10.1002/macp.201400377}, pages = {2437 -- 2445}, year = {2014}, abstract = {A series of multiblock copolymers (PDLCL) synthesized from oligo(omega-pentadecalactone) diol (OPDL) and oligo(epsilon-caprolactone) diol (OCL), which are linked by 2,2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI), is investigated by the Langmuir monolayer technique at the air-water interface. Brewster angle microscopy (BAM) and spectroscopic ellipsometry are employed to characterize the polymer film morphologies in situ. PDLCL containing >= 40 wt\% OCL segments form homogeneous Langmuir monofilms after spreading. The film elasticity modulus decreases with increasing amounts of OPDL segments in the copolymer. In contrast, the OCL-free polyesterurethane OPDL-TMDI cannot be spread to monomolecular films on the water surface properly, and movable slabs are observed by BAM even at low surface pressures. The results of the in situ morphological characterization clearly show that essential information concerning the reliability of Langmuir monolayer degradation (LMD) experiments cannot be obtained from the evaluation of the pi-A isotherms only. Consequently, in situ morphological characterization turns out to be indispensable for characterization of Langmuir layers before LMD experiments.}, language = {en} } @article{BhuvaneshMachatschekLysyakovaetal.2019, author = {Bhuvanesh, Thanga and Machatschek, Rainhard Gabriel and Lysyakova, Liudmila and Kratz, Karl and Schulz, Burkhard and Ma, Nan and Lendlein, Andreas}, title = {Collagen type-IV Langmuir and Langmuir-Schafer layers as model biointerfaces to direct stem cell adhesion}, series = {Biomedical materials : materials for tissue engineering and regenerative medicine}, volume = {14}, journal = {Biomedical materials : materials for tissue engineering and regenerative medicine}, number = {2}, publisher = {Inst. of Physics Publ.}, address = {Bristol}, issn = {1748-6041}, doi = {10.1088/1748-605X/aaf464}, pages = {17}, year = {2019}, abstract = {In biomaterial development, the design of material surfaces that mimic the extra-cellular matrix (ECM) in order to achieve favorable cellular instruction is rather challenging. Collagen-type IV (Col-IV), the major scaffolding component of Basement Membranes (BM), a specialized ECM with multiple biological functions, has the propensity to form networks by self-assembly and supports adhesion of cells such as endothelial cells or stem cells. The preparation of biomimetic Col-IV network-like layers to direct cell responses is difficult. We hypothesize that the morphology of the layer, and especially the density of the available adhesion sites, regulates the cellular adhesion to the layer. The Langmuir monolayer technique allows for preparation of thin layers with precisely controlled packing density at the air-water (A-W) interface. Transferring these layers onto cell culture substrates using the Langmuir-Schafer (LS) technique should therefore provide a pathway for preparation of BM mimicking layers with controlled cell adherence properties. In situ characterization using ellipsometry and polarization modulation-infrared reflection absorption spectroscopy of Col-IV layer during compression at the A-W interface reveal that there is linear increase of surface molecule concentration with negligible orientational changes up to a surface pressure of 25 mN m(-1). Smooth and homogeneous Col-IV network-like layers are successfully transferred by LS method at 15 mN m(-1) onto poly(ethylene terephthalate) (PET), which is a common substrate for cell culture. In contrast, the organization of Col-IV on PET prepared by the traditionally employed solution deposition method results in rather inhomogeneous layers with the appearance of aggregates and multilayers. Progressive increase in the number of early adherent mesenchymal stem cells (MSCs) after 24 h by controlling the areal Col-IV density by LS transfer at 10, 15 and 20 mN m(-1) on PET is shown. The LS method offers the possibility to control protein characteristics on biomaterial surfaces such as molecular density and thereby, modulate cell responses.}, language = {en} } @article{HoffmannDietzelSchulzetal.2011, author = {Hoffmann, Katrin and Dietzel, Birgit and Schulz, Burkhard and Reck, Guenter and Hoffmann, Angelika and Orgzall, Ingo and Resch-Genger, Ute and Emmerling, Franziska}, title = {Combined structural and fluorescence studies of methyl-substituted 2,5-diphenyl-1,3,4-oxadiazoles - Relation between electronic properties and packing motifs}, series = {Journal of molecular structure}, volume = {988}, journal = {Journal of molecular structure}, number = {1-3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2010.11.071}, pages = {35 -- 46}, year = {2011}, abstract = {Prerequisite for the rational design of functional organic materials with tailor-made electronic properties is the knowledge of the structure-property relationship for the specific class of molecules under consideration. This encouraged us to systematically study the influence of the molecular structure and substitution pattern of aromatically substituted 1,3,4-oxadiazoles on the electronic properties and packing motifs of these molecules and on the interplay of these factors. For this purpose, seven diphenyl-oxadiazoles equipped with methyl substituents in the ortho- and meta-position(s) were synthesized and characterized. Absorption and fluorescence spectra in solution served here as tools to monitor substitution-induced changes in the electronic properties of the individual molecules whereas X-ray and optical measurements in the solid state provided information on the interplay of electronic and packing effects. In solution, the spectral position of the absorption maximum, the size of Stokes shift, and the fluorescence quantum yield are considerably affected by ortho-substitution in three or four ortho-positions. This results in blue shifted absorption bands, increased Stokes shifts, and reduced fluorescence quantum yields whereas the spectral position and vibrational structure of the emission bands remain more or less unaffected. In the crystalline state, however, the spectral position and shape of the emission bands display a strong dependence on the molecular structure and/or packing motifs that seem to control the amount of dye-dye-interactions. These observations reveal the limited value of commonly reported absorption and fluorescence measurements in solution for a straightforward comparison of spectroscopic results with single X-ray crystallography. This underlines the importance of solid state spectroscopic studies for a better understanding of the interplay of electronic effects and molecular order.}, language = {en} } @article{ZhuSchulzBrumaetal.1996, author = {Zhu, Shigen and Schulz, Burkhard and Bruma, Maria and Brehmer, Ludwig}, title = {Comparative study of the thermal properties of related aromatic polyhydrazides and poly(1,3,4-oxadiazole)s}, issn = {1042-7147}, doi = {10.1002/(SICI)1099-1581(199612)7:12<879::AID-PAT600>3.0.CO;2-X}, year = {1996}, language = {en} } @article{SavaSzesztayBrumaetal.1997, author = {Sava, Ion and Szesztay, Marta and Bruma, Maria and Mercer, Frank W. and Schulz, Burkhard}, title = {Compared properties of aromatic polyamides containing silicon in the chain}, year = {1997}, abstract = {Two series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups have been synthesized and their properties have been characterized and compared with those of related polymers. These polymers are easily soluble in polar amidic solvents such as N-rnethyl-2-pyrrolidinone and dimethylformamide, and in tetrahydrofuran, and can be cast into thin, transparent films from solution. The polyamides have weight- and number-average molecular weights in the range of 10000-40000 and 3000-6000, respectively, and polydispersities in the range of 3-10. They show glass transition temperatures in the range of 236 °C-275 °C and decomposition temperatures above 400 °C. The polymer films have low dielectric constants in the range of 3.26-3.68, and good mechanical properties (tensile strength 74-100 MPa, tensile modulus 180-386 MPa), thus being comparable with other high performance dielectrics.}, language = {en} } @article{SavaBrumaSchulzetal.2005, author = {Sava, Ion and Bruma, Maria and Schulz, Burkhard and K{\"o}pnick, Thomas}, title = {Comparison of properties of silicon-containing poly(amide-imide)s}, issn = {0954-0083}, year = {2005}, abstract = {New silicon-containing poly(amide-imide)s have been synthesized by direct polycondensation of various aromatic diamines with a dicarboxylic acid containing the dimethylsilylene group and preformed in-tide cycles. These polymers are easily soluble in polar amidic solvents such as N-methylpyrrolidinone (NMP) or dimethylformamide (DMF) and can be cast into thin flexible films or coatings from such solutions. They show high thermal stability, with initial decomposition temperature being above 400 C and glass transition temperature in the range of 220-270 degrees C. Very thin polymer films deposited by spincoating technique onto silicon wafers showed a smooth, pinhole-free surface in atomic force microscopy investigations}, language = {en} } @article{SchulzStillerZetzscheetal.1994, author = {Schulz, Burkhard and Stiller, Burkhard and Zetzsche, Thomas and Knochenhauer, Gerald and Dietel, Reinhard and Brehmer, Ludwig}, title = {Crystal structure of 2,5-Di(4- methoxycarbonyl-phenyl)-1,3,4-oxadiazole characterized by AFM and IR- spectroscopy}, year = {1994}, language = {en} } @article{OkatovaAndreevaSchulzetal.1999, author = {Okatova, Olga V. and Andreeva, Katharina A. and Schulz, Burkhard and Lavrenko, Peter N.}, title = {Degradation of poly(m-phenylene oxadiazole) in concentrated sulfuric acid}, year = {1999}, language = {en} } @article{SarauliXuDietzeletal.2013, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {Differently substituted sulfonated polyanilines - the role of polymer compositions in electron transfer with pyrroloquinoline quinone-dependent glucose dehydrogenase}, series = {Acta biomaterialia}, volume = {9}, journal = {Acta biomaterialia}, number = {9}, publisher = {Elsevier}, address = {Oxford}, issn = {1742-7061}, doi = {10.1016/j.actbio.2013.06.008}, pages = {8290 -- 8298}, year = {2013}, abstract = {Sulfonated polyanilines have become promising building blocks in the construction of biosensors, and therefore we use here differently substituted polymer forms to investigate the role of their structural composition and properties in achieving a direct electron transfer with the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH). To this end, new copolymers containing different ratios of 2-methoxyaniline-5-sulfonic acid (MAS), 3-aminobenzenesulfonic acid (ABS) and 3-aminobenzoic acid (AB) units have been chemically synthesized. All polymers have been studied with respect to their ability to react directly with PQQ-GDH. This interaction has been monitored initially in solution, and subsequently on electrode surfaces. The results show that only copolymers with MAS and aniline units can directly react with PQQ-GDH in solution; the background can be mainly ascribed to the emeraldine salt redox state of the polymer, allowing rather easy reduction. However, when polymers and the enzyme are immobilized on the surface of carbon nanotube-containing electrodes, direct bioelectrocatalysis is also feasible in the case of copolymers composed of ABS/AB and MAS/AB units, existing initially in pernigraniline base form. This verifies that a productive interaction of the enzyme with differently substituted polymers is feasible when the electrode potential can be used to drive the reaction towards the oxidation of the substrate-reduced enzyme. These results clearly demonstrate that enzyme electrodes based on sulfonated polyanilines and direct bioelectrocatalysis can be successfully constructed.}, language = {en} } @article{TanneJeoungPengetal.2015, author = {Tanne, Johannes and Jeoung, Jae-Hun and Peng, Lei and Yarman, Aysu and Dietzel, Birgit and Schulz, Burkhard and Schad, Daniel and Dobbek, Holger and Wollenberger, Ursula and Bier, Frank Fabian and Scheller, Frieder W.}, title = {Direct Electron Transfer and Bioelectrocatalysis by a Hexameric, Heme Protein at Nanostructured Electrodes}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {27}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, number = {10}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1040-0397}, doi = {10.1002/elan.201500231}, pages = {2262 -- 2267}, year = {2015}, abstract = {A nanohybrid consisting of poly(3-aminobenzenesulfonic acid-co-aniline) and multiwalled carbon nanotubes [MWCNT-P(ABS-A)]) on a gold electrode was used to immobilize the hexameric tyrosine-coordinated heme protein (HTHP). The enzyme showed direct electron transfer between the heme group of the protein and the nanostructured surface. Desorption of the noncovalently bound heme from the protein could be excluded by control measurements with adsorbed hemin on aminohexanthiol-modified electrodes. The nanostructuring and the optimised charge characteristics resulted in a higher protein coverage as compared with MUA/MU modified electrodes. The adsorbed enzyme shows catalytic activity for the cathodic H2O2 reduction and oxidation of NADH.}, language = {en} } @article{LavrenkoStrelinaSchulz1997, author = {Lavrenko, Peter N. and Strelina, Irina A. and Schulz, Burkhard}, title = {Dynamo-optical properties of poly(naphthylene oxadiazole)s in sulfuric acid}, year = {1997}, abstract = {Flow birefringence induced in dilute solutions of poly[(1,4-naphthylene)-2,5-diyl-1,3,4-oxadiazole] and poly[2,6-naphthylene)-2,5-diyl-1,3,4-oxadiazole] in conc. sulphuric acid has been investigated. The shear optical coefficient was found for these polymers to be approximately double the value of that obtained in the same solvent for poly[(para-phenylene) -2,5-diyl-1,3,4-oxadiazole]. Rigid-chain behaviour of the polymers was characterized by hydrodynamic and dynamo-optical parameters evaluated with application of the worm-like chain model and the "method of similar structures". Change in optical anisotropy of a chain unit induced by incorporation of naphthylene groups into the main chain has been evaluated.}, language = {en} } @article{SaracGencturkGilsingetal.2009, author = {Sarac, A. Sezai and Gencturk, Asli and Gilsing, Hans-Detlev and Schulz, Burkhard and Turhan, C. Metehan}, title = {Effect of electrolyte on the electropolymerization of 2,2-dibutyl-3,4-propylenedioxythiophene on carbon fiber microelectrodes}, issn = {1533-4880}, doi = {10.1166/Jnn.2009.027}, year = {2009}, abstract = {Electrocoating of 2,2 dibutylpropylene dioxythiophene on carbon fiber microelectrodes (CFMEs) in different electrolytes in acetonitrile was performed, and surface morphology and electrochemical impedance spectroscopic investigation has been carried out. Impedance spectra showed the typical form of Z(IM) versus Z(RE) for transmission- line at frequencies 10 Hz, with transition to almost pure capacitive behaviour down to 10 mHz (the lower limit of frequency scan).}, language = {en} } @article{Schulz1994, author = {Schulz, Burkhard}, title = {Eine neue Synthesevariante f{\"u}r aromatische Poly(1,3,4-oxadiazole)}, year = {1994}, language = {de} } @article{TurhanSaracGencturketal.2012, author = {Turhan, Metehan C. and Sarac, A. Sezai and Gencturk, Asli and Gilsing, Hans-Detlev and Faltz, Heike and Schulz, Burkhard}, title = {Electrochemical impedance characterization and potential dependence of poly[3,4-(2,2-dibutylpropylenedioxy)thiophene] nanostructures on single carbon fiber microelectrode}, series = {Synthetic metals : the journal of electronic polymers and electronic molecular materials}, volume = {162}, journal = {Synthetic metals : the journal of electronic polymers and electronic molecular materials}, number = {5-6}, publisher = {Elsevier}, address = {Lausanne}, issn = {0379-6779}, doi = {10.1016/j.synthmet.2012.01.012}, pages = {511 -- 515}, year = {2012}, abstract = {The electropolymerization of 3,4-(2,2-dibutylpropylenedioxy)thiophene (ProDOT-Bu-2) onto single carbon fiber microelectrode (SCFME) was conducted in acetonitrile (ACN) containing sodium perchlorate (NaClO4) as electrolyte and investigated by cyclic voltammetry (CV). The nanostructured films of poly[3,4-(2,2-dibutyl-propyleneclioxy)thiophene] (PProDOT-Bu-2) which were depositing showed complete reversible redox behavior in monomer-free electrolyte solution. The capacitive behavior of the films was investigated by electrochemical impedance spectroscopy (EIS) at applied potentials from 0.1 V to 1.3 V. The analysis by equivalent circuit modeling revealed an applied potential around 0.4V to be most suitable for the system PProDOT-Bu-2/SCFME as a double layer supercapacitor component inducing a double layer capacitance C-d, value of 62 mFcm(-2).}, language = {en} } @article{JanietzSchulz1996, author = {Janietz, Silvia and Schulz, Burkhard}, title = {Electrochemical investigation on poly(arylene-1,3,4-oxadiazole)s}, year = {1996}, language = {en} } @article{SchulzJanietz1994, author = {Schulz, Burkhard and Janietz, Silvia}, title = {Electrochemical studies on thin films of poly(arylene 1,3,4-oxadiazole)s}, year = {1994}, language = {en} } @article{JanietzSchulz1994, author = {Janietz, Silvia and Schulz, Burkhard}, title = {Electrochemical studies on thin films of poly(arylene-1,3,4-oxadiazole)s}, year = {1994}, language = {en} } @article{JanietzSchulz1995, author = {Janietz, Silvia and Schulz, Burkhard}, title = {Elektrochemische Untersuchungen an aromatischen Poly(1,3,4-oxadiazol)en}, year = {1995}, language = {de} } @article{NieWangXuetal.2019, author = {Nie, Yan and Wang, Weiwei and Xu, Xun and Zou, Jie and Bhuvanesh, Thanga and Schulz, Burkhard and Ma, Nan and Lendlein, Andreas}, title = {Enhancement of human induced pluripotent stem cells adhesion through multilayer laminin coating}, series = {Clinical hemorheology and microcirculation : blood flow and vessels}, volume = {70}, journal = {Clinical hemorheology and microcirculation : blood flow and vessels}, number = {4}, publisher = {IOS Press}, address = {Amsterdam}, issn = {1386-0291}, doi = {10.3233/CH-189318}, pages = {531 -- 542}, year = {2019}, abstract = {Bioengineered cell substrates are a highly promising tool to govern the differentiation of stem cells in vitro and to modulate the cellular behavior in vivo. While this technology works fine for adult stem cells, the cultivation of human induced pluripotent stem cells (hiPSCs) is challenging as these cells typically show poor attachment on the bioengineered substrates, which among other effects causes substantial cell death. Thus, very limited types of surfaces have been demonstrated suitable for hiPSC cultures. The multilayer coating approach that renders the surface with diverse chemical compositions, architectures, and functions can be used to improve the adhesion of hiPSCs on the bioengineered substrates. We hypothesized that a multilayer formation based on the attraction of molecules with opposite charges could functionalize the polystyrene (PS) substrates to improve the adhesion of hiPSCs. Polymeric substrates were stepwise coated, first with dopamine to form a polydopamine (PDA) layer, second with polylysine and last with Laminin-521. The multilayer formation resulted in the variation of hydrophilicity and chemical functionality of the surfaces. Hydrophilicity was detected using captive bubble method and the amount of primary and secondary amines on the surface was quantified by fluorescent staining. The PDA layer effectively immobilized the upper layers and thereby improved the attachment of hiPSCs. Cell adhesion was enhanced on the surfaces coated with multilayers, as compared to those without PDA and/or polylysine. Moreover, hiPSCs spread well over this multilayer laminin substrate. These cells maintained their proliferation capacity and differentiation potential. The multilayer coating strategy is a promising attempt for engineering polymer-based substrates for the cultivation of hiPSCs and of interest for expanding the application scope of hiPSCs.}, language = {en} } @phdthesis{Schulz1997, author = {Schulz, Burkhard}, title = {Entwicklung aromatischer Poly(1,3,4-oxadiazo)e zu Funktionsmaterialien : Beitr{\"a}ge durch chemische Modifizierung und supramolekulare Strukturierung}, address = {Potsdam}, pages = {getr. Z{\"a}hl.: graph. Darst.}, year = {1997}, language = {de} } @article{RossbergRottkeSchulzetal.2016, author = {Rossberg, Joana and Rottke, Falko O. and Schulz, Burkhard and Lendlein, Andreas}, title = {Enzymatic Degradation of Oligo(epsilon-caprolactone)s End-Capped with Phenylboronic Acid Derivatives at the Air-Water Interface}, series = {Macromolecular rapid communications}, volume = {37}, journal = {Macromolecular rapid communications}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201600471}, pages = {1966 -- 1971}, year = {2016}, abstract = {The influence of terminal functionalization of oligo(epsilon-caprolactone)s (OCL) with phenylboronic acid pinacol ester or phenylboronic acid on the enzymatic degradation behavior at the air-water interface is investigated by the Langmuir monolayer degradation technique. While the unsubstituted OCL immediately degrades after injection of the enzyme lipase from Pseudomonas cepacia, enzyme molecules are incorporated into the films based on end-capped OCL before degradation. This incorporation of enzymes does not inhibit or suppress the film degradation, but retards it significantly. A specific binding of lipase to the polymer monolayer allows studying the enzymatic activity of bound proteins and the influence on the degradation process. The functionalization of a macromolecule with phenyl boronic acid groups is an approach to investigate their interactions with diol-containing biomolecules like sugars and to monitor their specified impact on the enzymatic degradation behavior at the air-water interface.}, language = {en} } @misc{SchoeneRochSchulzetal.2017, author = {Sch{\"o}ne, Anne-Christin and Roch, Toralf and Schulz, Burkhard and Lendlein, Andreas}, title = {Evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer techniques}, series = {Interface : journal of the Royal Society}, volume = {14}, journal = {Interface : journal of the Royal Society}, publisher = {Royal Society}, address = {London}, issn = {1742-5689}, doi = {10.1098/rsif.2016.1028}, pages = {18}, year = {2017}, abstract = {Polymeric biomaterials are of specific relevance in medical and pharmaceutical applications due to their wide range of tailorable properties and functionalities. The knowledge about interactions of biomaterials with their biological environment is of crucial importance for developing highly sophisticated medical devices. To achieve optimal in vivo performance, a description at the molecular level is required to gain better understanding about the surface of synthetic materials for tailoring their properties. This is still challenging and requires the comprehensive characterization of morphological structures, polymer chain arrangements and degradation behaviour. The review discusses selected aspects for evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer methods as powerful techniques for studying interfacial properties, such as morphological and degradation processes. The combination of spectroscopic, microscopic and scattering methods with the Langmuir techniques adapted to polymers can substantially improve the understanding of their in vivo behaviour.}, language = {en} } @article{BrumaMercerSchulzetal.1994, author = {Bruma, Maria and Mercer, Frank W. and Schulz, Burkhard and Dietel, Reinhard and Neumann, Werner}, title = {Fluorinated poly(benzoxazole-imide)s}, year = {1994}, language = {en} } @article{KarageorgievNeherSchulzetal.2005, author = {Karageorgiev, Peter and Neher, Dieter and Schulz, Burkhard and Stiller, Burkhard and Pietsch, Ullrich and Giersig, Michael and Brehmer, Ludwig}, title = {From anisotropic photo-fluidity towards nanomanipulation in the optical near-field}, issn = {1476-1122}, year = {2005}, abstract = {An increase in random molecular vibrations of a solid owing to heating above the melting point leads to a decrease in its long-range order and a loss of structural symmetry. Therefore conventional liquids are isotropic media. Here we report on a light-induced isothermal transition of a polymer film from an isotropic solid to an anisotropic liquid state in which the degree of mechanical anisotropy can be controlled by light. Whereas during irradiation by circular polarized light the film behaves as an isotropic viscoelastic fluid, it shows considerable fluidity only in the direction parallel to the light field vector under linear polarized light. The fluidization phenomenon is related to photoinduced motion of azobenzene-functionalized molecular units, which can be effectively activated only when their transition dipole moments are oriented close to the direction of the light polarization. We also describe here how the photofluidization allows nanoscopic elements of matter to be precisely manipulated}, language = {en} } @article{Schulz1996, author = {Schulz, Burkhard}, title = {Herstellung und Charakterisierung geordneter ultrad{\"u}nner Poly(arylen- 1,3,4-oxadiazol) Schichten}, year = {1996}, language = {de} } @article{BrumaHamciucHamciucetal.1996, author = {Bruma, Maria and Hamciuc, Corneliu and Hamciuc, Elena and Mercer, Frank W. and Belomoina, Nataliya and Schulz, Burkhard}, title = {Heterocyclic polyamides containing hexafluoroisopropylidene groups}, year = {1996}, language = {en} } @article{BrumaHamciucHamciucetal.1997, author = {Bruma, Maria and Hamciuc, Corneliu and Hamciuc, Elena and Mercer, Frank W. and Belomoina, Nataliya and Schulz, Burkhard}, title = {Heterocyclic polyamides containing hexafluoroisopropylidene groups}, year = {1997}, abstract = {New heterocyclic polyamides have been synthesized by solution polycondensation of aromatic diamines containing phenyl- quinoxaline units with diacid chlorides having both imide and hexafluoroisopropylidene (6F) groups. These polymers are soluble in polar aprotic solvents, such as N-methylpyrrolidone (NMP) or N,N-dimethylformamide (DMF), and can be cast into flexible thin films from solutions. They show high thermooxidative stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 225 - 300°C. The polymer films exhibit good chemical resistance towards deluted acids and good electrical insulating properties with dielectric constants in the range of 3.2 - 3.7.}, language = {en} } @article{OrgzallFrancoSchulz2006, author = {Orgzall, Ingo and Franco, Olga and Schulz, Burkhard}, title = {High pressure structural investigations of 2,5-di(4-pyridyl)-1,3,4-oxadiazole - importance of strain studies for the description of intermolecular interactions}, doi = {10.1088/0953-8984/18/23/001}, year = {2006}, abstract = {Results of a high pressure x-ray study of 2,5-di(4-pyridyl)-1,3,4-oxadiazole up to 2.5 GPa are presented and discussed. Parameters for the Murnaghan equation of state are derived. The bulk modulus amounts to K-0 = 4.6 +/- 0.3 GPa and its pressure derivative to K-0' = 7.4 +/- 0.6. These values are comparable to values of other diphenyl-1,3,4- oxadiazoles. The anisotropy of the compression is analysed using the strain tensor and discussed based on the anisotropy of the intermolecular interactions}, language = {en} } @article{BrumaHamciucSavaetal.1996, author = {Bruma, Maria and Hamciuc, Corneliu and Sava, Ion and Hamciuc, Elena and Mercer, Frank W. and Fritzsche, P. and Schulz, Burkhard}, title = {High temperature polyamides containing pendant imide groups}, year = {1996}, language = {en} } @article{OrgzallFrancoRecketal.2005, author = {Orgzall, Ingo and Franco, Olga and Reck, Guenter and Schulz, Burkhard}, title = {High-pressure studies on fluorine substituted 2,5-di(phenyl)-1,3,4-oxadiazoles}, issn = {0022-2860}, year = {2005}, abstract = {Results are presented from structural and high-pressure investigations on four differently but symmetrically fluorine substituted 2,5di(phenyl)-1,3,4-oxadiazoles. The substitution pattern includes the para-, meta-, or ortho- substitution and the fully fluorinated 2,5-bis(pentafluorophenyl)-1,3,4-oxadiazole. The crystal structure depends on the molecular structure and results in a different high-pressure behavior. Parameters for the Murnaghan equation of state (EOS) are determined for every compound and the anisotropic pressure response of the crystal lattice is discussed. Although the EOS parameters, bulk modulus K. and its pressure derivative K'(o) are of the same order of magnitude for all four compounds, the anisotropy of strain is noticeably different. (c) 2005 Elsevier B.V. All rights reserved}, language = {en} } @article{LavrenkoOkatovaSchulzetal.1999, author = {Lavrenko, Peter N. and Okatova, Olga V. and Schulz, Burkhard and Andreeva, Katharina A. and Strelina, Irina A.}, title = {Hydrodynamic and dynamo-optical properties of poly(1,3-phenylene-1,3,4-oxadiazole) molecules in sulphuric acid}, year = {1999}, abstract = {Translational diffusion of the macromolecules, intrinsic viscosity and flow birefringence induced in dilute solutions of poly(1,3-phenylene-1,3,4-oxadiazole) (PMOD) in conc. sulphuric acid has been investigated. Molecular-weight dependences of hydrodynamic and dynamo-optical properties are established over the M range from 8.1 103 to 87 103. Experimental data agree well with the theories developed for translational friction and intrinsic viscosity of the wormlike chains with the following molecular parameters: mass per chain unit ML = 22.7 Dalton/{\AA}, the Kuhn segment length A = 59 ± 4 {\AA}, the chain diameter d = 4 ± 1.5 {\AA}. Hindrance to intramolecular rotation is characterized by the parameter s = 1.7. The shear optical coefficient was found to be approximately 1.7 times lower the value of that obtained in the same solvent for the para-phenylene isomer of this polymer, being in good agreement with higher equilibrium flexibility of the PMOD molecule chains in solutions as determined herein from the hydrodynamic data.}, language = {en} } @article{LavrenkoOkatovaSchulz1998, author = {Lavrenko, Peter N. and Okatova, Olga V. and Schulz, Burkhard}, title = {Hydrodynamic properties and conformation of the molecules of meta- and para-isomers of polyphenyleneoxadiazole in sulphuric acid}, year = {1998}, abstract = {Translational diffusion of poly(1,4-phenylene-1,3,4-oxadiazole) in 96\% H2S04 was studied, and the intrinsic viscosity of the polymer solution was measured in various stages of degradation at temperatures from 82 to 105°C. The rate constant of the degradation process was determined from variation of the molecular mass of the degradation products with time at a fixed solution temperature, and the activation energy of the process was calculated using the temperature dependence of the rate constant. The activation energy (E = 103 ± 7 kJ/mol) is lower than that for the hydrolysis of aromatic polyamides in sulfuric acid. According to the hydrodynamic data, the degree of coiling of the degradation products is the saine as that of the intact (non-degraded) macromolecules. This indicates that elements of the chernical structure responsible for the short-range order in the macromolecular chain are retained in the course of degradation.}, language = {en} } @article{LavrenkoOkatovaCherkasovetal.1998, author = {Lavrenko, Peter N. and Okatova, Olga V. and Cherkasov, Victor A. and Schulz, Burkhard}, title = {Hydrodynamic properties of Poly(p-phenylene-oxadiazole) in various stages of hydrolytic thermal degradation in sulfuric acid}, year = {1998}, language = {en} } @article{GulerGilsingSchulzetal.2012, author = {Guler, Fatma G. and Gilsing, Hans-Detlev and Schulz, Burkhard and Sarac, A. Sezai}, title = {Impedance and morphology of hydroxy- and chloro-functionalized poly(3,4-propylenedioxythiophene) nanostructures}, series = {Journal of nanoscience and nanotechnolog}, volume = {12}, journal = {Journal of nanoscience and nanotechnolog}, number = {10}, publisher = {American Scientific Publ.}, address = {Valencia}, issn = {1533-4880}, doi = {10.1166/jnn.2012.6594}, pages = {7869 -- 7878}, year = {2012}, abstract = {The new 3,4-propylenedioxythiophenes (ProDOT) bearing hydroxy- or chloro-functionalized side chains of varying length and polarity were synthesized and electropolymerized on single carbon fiber microelectrode (SCFME) using cyclo-voltammetry. Electrochemical impedance spectroscopy (EIS) revealed highest capacitance values for the hydroxy-functionalized Poly 5 carrying a side chain of medium length. The EIS data were fitted with an equivalent electrical circuit giving a good correlation. AFM analysis of the topography showed higher roughness values for Poly 5 than for the two other polymers bearing longer side chains. Due to their reactive end groups the polymers should be useful for post-polymerization functionalization of the electrode surface.}, language = {en} } @article{SchoeneRichauKratzetal.2015, author = {Sch{\"o}ne, Anne-Christin and Richau, Klaus and Kratz, Karl and Schulz, Burkhard and Lendlein, Andreas}, title = {Influence of Diurethane Linkers on the Langmuir Layer Behavior of Oligo[(rac-lactide)-co-glycolide]-based Polyesterurethanes}, series = {Macromolecular rapid communications}, volume = {36}, journal = {Macromolecular rapid communications}, number = {21}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201500316}, pages = {1910 -- 1915}, year = {2015}, abstract = {Three oligo[(rac-lactide)-co-glycolide] based polyesterurethanes (OLGA-PUs) containing different diurethane linkers are investigated by the Langmuir monolayer technique and compared to poly[(rac-lactide)-co-glycolide] (PLGA) to elucidate the influence of the diurethane junction units on hydrophilicity and packing motifs of these polymers at the air-water interface. The presence of diurethane linkers does not manifest itself in the Langmuir layer behavior both in compression and expansion experiments when monomolecular films of OLGA-PUs are spread on the water surface. However, the linker retard the evolution of morphological structures at intermediate compression level under isobaric conditions (with a surface pressure greater than 11 mN m(-1)) compared to the PLGA, independent on the chemical structure of the diurethane moiety. The layer thicknesses of both OLGA-PU and PLGA films decrease in the high compression state with decreasing surface pressure, as deduced from ellipsometric data. All films must be described with the effective medium approximation as water swollen layers.}, language = {en} } @article{MachatschekSchoeneRaschdorfetal.2019, author = {Machatschek, Rainhard Gabriel and Sch{\"o}ne, Anne-Christin and Raschdorf, Elisa and Ihlenburg, Ramona and Schulz, Burkhard and Lendlein, Andreas}, title = {Interfacial properties of morpholine-2,5-dione-based oligodepsipeptides and multiblock copolymers}, series = {MRS Communications}, volume = {9}, journal = {MRS Communications}, number = {1}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {2159-6859}, doi = {10.1557/mrc.2019.21}, pages = {170 -- 180}, year = {2019}, abstract = {Oligodepsipeptides (ODPs) with alternating amide and ester bonds prepared by ring-opening polymerization of morpholine-2,5-dione derivatives are promising matrices for drug delivery systems and building blocks for multifunctional biomaterials. Here, we elucidate the behavior of three telechelic ODPs and one multiblock copolymer containing ODP blocks at the air-water interface. Surprisingly, whereas the oligomers and multiblock copolymers crystallize in bulk, no crystallization is observed at the air-water interface. Furthermore, polarization modulation infrared reflection absorption spectroscopy is used to elucidate hydrogen bonding and secondary structures in ODP monolayers. The results will direct the development of the next ODP-based biomaterial generation with tailored properties for highly sophisticated applications.}, language = {en} } @misc{MachatschekSchoeneRaschdorfetal.2019, author = {Machatschek, Rainhard Gabriel and Sch{\"o}ne, Anne-Christin and Raschdorf, Elisa and Ihlenburg, Ramona and Schulz, Burkhard and Lendlein, Andreas}, title = {Interfacial properties of morpholine-2,5-dione-based oligodepsipeptides and multiblock copolymers}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1106}, issn = {1866-8372}, doi = {10.25932/publishup-46975}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-469755}, pages = {170 -- 180}, year = {2019}, abstract = {Oligodepsipeptides (ODPs) with alternating amide and ester bonds prepared by ring-opening polymerization of morpholine-2,5-dione derivatives are promising matrices for drug delivery systems and building blocks for multifunctional biomaterials. Here, we elucidate the behavior of three telechelic ODPs and one multiblock copolymer containing ODP blocks at the air-water interface. Surprisingly, whereas the oligomers and multiblock copolymers crystallize in bulk, no crystallization is observed at the air-water interface. Furthermore, polarization modulation infrared reflection absorption spectroscopy is used to elucidate hydrogen bonding and secondary structures in ODP monolayers. The results will direct the development of the next ODP-based biomaterial generation with tailored properties for highly sophisticated applications.}, language = {en} } @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{BrumaSchulzKoepnicketal.1998, author = {Bruma, Maria and Schulz, Burkhard and K{\"o}pnick, Thomas and Dietel, Reinhard and Stiller, Burkhard and Mercer, Frank W.}, title = {Investigation of thin films made from silicon-containing poly(phenylquinoxaline-amide)s}, year = {1998}, abstract = {Thin films in the range of 50 nm to 10 mm thickness have been prepared from NMP solutions of silicon-containing polyphenylquinoxaline-amides which had been synthesized by the polycondensation reaction of aromatic diaminophenylquinoxalines with bis(p-chlorocarbonylphenyl)diphenylsilane. A spin-coating technique onto glass plates or onto silicon wafers was used to make the film, followed by gradual heating to remove the solvent. The resulting films were very smooth and free of pinholes when studied by atomic force microscopy (AFM). They showed a strong adhesion to silicon wafers, were thermally stable in air to above 400 °C and their dielectric constant was in the range of 3.5-3.7. Thermal treatment of the films was performed in order to induce crosslinking. Such treated films became completely insoluble in organic solvents, maintained their smoothness and strong adhesion to the silicon substrate, and did not show any Tg, in DSC experiments. Their FTIR spectra in reflection mode did not show any changes compared with the untreated films, meaning on the one hand that the polymers maintain their structural integrity at high temperature and on the other hand that the number of crosslinks was very low and could not be detected by IR spectroscopy.}, language = {en} }