TY - JOUR A1 - Weiss, Jan A1 - Li, Ang A1 - Wischerhoff, Erik A1 - Laschewsky, André T1 - Water-soluble random and alternating copolymers of styrene monomers with adjustable lower critical solution temperature JF - Polymer Chemistry N2 - Random copolymers of 4-vinylbenzyl tri(oxyethylene) and tetra(oxyethylene) ethers, as well as alternating copolymers of 4-vinylbenzyl methoxytetra(oxyethylene) ether and a series of N-substituted maleimides, were synthesised by conventional free radical polymerisation, reversible addition fragmentation chain transfer (RAFT) and atom transfer radical polymerisation (ATRP). Their thermosensitive behaviour in aqueous solution was studied by turbidimetry and dynamic light scattering. Depending on the copolymer composition, a LCST type phase transition was observed in water. The transition temperature of the obtained random as well as alternating copolymers could be varied within a broad temperature window. In the case of the random copolymers, transition temperatures could be easily fine-tuned, as they showed a linear dependence on the copolymer composition, and were additionally modified by the nature of the polymer end-groups. Alternating copolymers were extremely versatile for implementing a broad range of variations of the phase transition temperatures. Further, while alternating copolymers derived from 4-vinylbenzyl methoxytetra(oxyethylene) ether and maleimides with small hydrophobic side chains underwent macroscopic phase separation when dissolved in water and heated above their cloud point, the incorporation of maleimides bearing larger hydrophobic substituents resulted in the formation of mesoglobules above the phase transition temperature, with hydrodynamic diameters of less than 100 nm. Y1 - 2012 U6 - https://doi.org/10.1039/c1py00422k SN - 1759-9954 VL - 3 IS - 2 SP - 352 EP - 361 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Wischerhoff, Erik A1 - Glatzel, Stefan A1 - Uhlig, Katja A1 - Lankenau, Andreas A1 - Lutz, Jean-Francois A1 - Laschewsky, André T1 - Tuning the thickness of polymer brushes grafted from nonlinearly growing multilayer assemblies N2 - A new versatile method for tuning the thickness of surface-tethered polymer brushes is introduced. It is based on the combination of polyelectrolyte multilayer deposition and surface-initiated atom transfer radical polymerization. To control the thickness of the brushes, the nonlinear growth of certain polyelectrolyte multilayer systems is exploited. The method is demonstrated to work with different polyelectrolytes and different monomers. The relevance for applications is demonstrated by cell adhesion experiments oil grafted thermoresponsive polymer layers with varying thickness. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La804197j SN - 0743-7463 ER - TY - JOUR A1 - Buller, Jens A1 - Laschewsky, André A1 - Lutz, Jean-Francois A1 - Wischerhoff, Erik T1 - Tuning the lower critical solution temperature of thermoresponsive polymers by biospecific recognition JF - Polymer Chemistry N2 - A thermosensitive statistical copolymer based on oligo(ethylene glycol) methacrylates incorporating biotin was synthesized by free radical copolymerisation. The influence of added avidin on its thermoresponsive behaviour was investigated. The specific binding of avidin to the biotinylated copolymers provoked a marked increase of the lower critical solution temperature. Y1 - 2011 U6 - https://doi.org/10.1039/c1py00001b SN - 1759-9954 VL - 2 IS - 7 SP - 1486 EP - 1489 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Couturier, Jean-Philippe A1 - Wischerhoff, Erik A1 - Bernin, Robert A1 - Hettrich, Cornelia A1 - Koetz, Joachim A1 - Sutterlin, Martin A1 - Tiersch, Brigitte A1 - Laschewsky, Andre T1 - Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols JF - Langmuir N2 - Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers’ cloud point, or the induced changes of the hydrogels’ swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b00803 SN - 0743-7463 VL - 32 SP - 4333 EP - 4345 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Pinyou, Piyanut A1 - Ruff, Adrian A1 - Poeller, Sascha A1 - Barwe, Stefan A1 - Nebel, Michaela A1 - Alburquerque, Natalia Guerrero A1 - Wischerhoff, Erik A1 - Laschewsky, Andre A1 - Schmaderer, Sebastian A1 - Szeponik, Jan A1 - Plumere, Nicolas A1 - Schuhmann, Wolfgang T1 - Thermoresponsive amperometric glucose biosensor JF - Biointerphases N2 - The authors report on the fabrication of a thermoresponsive biosensor for the amperometric detection of glucose. Screen printed electrodes with heatable gold working electrodes were modified by a thermoresponsive statistical copolymer [polymer I: poly(omega-ethoxytriethylenglycol methacrylate-omega-3-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) propanesulfonate-co-omega-butoxydiethylenglycol methacrylate-co-2-(4-benzoyl-phenoxy)ethyl methacrylate)] with a lower critical solution temperature of around 28 degrees C in aqueous solution via electrochemically induced codeposition with a pH-responsive redox-polymer [polymer II: poly(glycidyl methacrylate-co-allyl methacrylate-co-poly(ethylene glycol) methacrylate-co-butyl acrylate-co-2-(dimethylamino) ethyl methacrylate)-[Os(bpy)(2)(4-(((2-(2-(2-aminoethoxy) ethoxy) ethyl) amino) methyl)-N,N-dimethylpicolinamide)](2+)] and pyrroloquinoline quinone-soluble glucose dehydrogenase acting as biological recognition element. Polymer II bears covalently bound Os-complexes that act as redox mediators for shuttling electrons between the enzyme and the electrode surface. Polymer I acts as a temperature triggered immobilization matrix. Probing the catalytic current as a function of the working electrode temperature shows that the activity of the biosensor is dramatically reduced above the phase transition temperature of polymer I. Thus, the local modulation of the temperature at the interphase between the electrode and the bioactive layer allows switching the biosensor from an on-to an off-state without heating of the surrounding analyte solution. (C) 2015 American Vacuum Society. Y1 - 2016 U6 - https://doi.org/10.1116/1.4938382 SN - 1934-8630 SN - 1559-4106 VL - 11 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Schönemann, Eric A1 - Koc, Julian A1 - Aldred, Nick A1 - Clare, Anthony S. A1 - Laschewsky, André A1 - Rosenhahn, Axel A1 - Wischerhoff, Erik T1 - Synthesis of Novel Sulfobetaine Polymers with Differing Dipole Orientations in Their Side Chains, and Their Effects on the Antifouling Properties JF - Macromolecular rapid communications N2 - The impact of the orientation of zwitterionic groups, with respect to the polymer backbone, on the antifouling performance of thin hydrogel films made of polyzwitterions is explored. In an extension of the recent discussion about differences in the behavior of polymeric phosphatidylcholines and choline phosphates, a quasi-isomeric set of three poly(sulfobetaine methacrylate)s is designed for this purpose. The design is based on the established monomer 3-[N-2-(methacryloyloxy)ethyl-N,N-dimethyl]ammonio-propane-1-sulfonate and two novel sulfobetaine methacrylates, in which the positions of the cationic and the ionic groups relative to the polymerizable group, and thus also to the polymer backbone, are altered. The effect of the varied segmental dipole orientation on their water solubility, wetting behavior by water, and fouling resistance is compared. As model systems, the adsorption of the model proteins bovine serum albumin (BSA), fibrinogen, and lysozyme onto films of the various polyzwitterion surfaces is studied, as well as the settlement of a diatom (Navicula perminuta) and barnacle cyprids (Balanus improvisus) as representatives of typical marine fouling communities. The results demonstrate the important role of the zwitterionic group's orientation on the polymer behavior and fouling resistance. KW - antifouling KW - coatings KW - crosslinking KW - hydrophilic polymers KW - polyzwitterions Y1 - 2019 U6 - https://doi.org/10.1002/marc.201900447 SN - 1022-1336 SN - 1521-3927 VL - 41 IS - 1 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Comminges, Clement A1 - Frasca, Stefano A1 - Suetterlin, Martin A1 - Wischerhoff, Erik A1 - Laschewsky, André A1 - Wollenberger, Ursula T1 - Surface modification with thermoresponsive polymer brushes for a switchable electrochemical sensor JF - RSC Advances N2 - Elaboration of switchable surfaces represents an interesting way for the development of a new generation of electrochemical sensors. In this paper, a method for growing thermoresponsive polymer brushes from a gold surface pre-modified with polyethyleneimine (PEI), subsequent layer-by-layer polyelectrolyte assembly and adsorption of a charged macroinitiator is described. We propose an easy method for monitoring the coil-to-globule phase transition of the polymer brush using an electrochemical quartz crystal microbalance with dissipation (E-QCM-D). The surface of these polymer modified electrodes shows reversible switching from the swollen to the collapsed state with temperature. As demonstrated from E-QCM-D measurements using an original signal processing method, the switch is operating in three reversible steps related to different interfacial viscosities. Moreover, it is shown that the one electron oxidation of ferrocene carboxylic acid is dramatically affected by the change from the swollen to the collapsed state of the polymer brush, showing a spectacular 86% decrease of the charge transfer resistance between the two states. Y1 - 2014 U6 - https://doi.org/10.1039/c4ra07190e SN - 2046-2069 VL - 4 IS - 81 SP - 43092 EP - 43097 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Wischerhoff, Erik A1 - Badi, Nezha A1 - Lutz, Jean-Francois A1 - Laschewsky, André T1 - Smart bioactive surfaces N2 - The purpose of this highlight is to define the emerging field of bioactive surfaces. In recent years, various types of synthetic materials capable of "communicating'' with biological objects such as nucleic acids, proteins, polysaccharides, viruses, bacteria or living cells have been described in the literature. This novel area of research certainly goes beyond the traditional field of smart materials and includes different types of sophisticated interactions with biological entities, such as reversible adhesion, conformational control, biologically-triggered release and selective permeation. These novel materials may be 2D planar surfaces as well as colloidal objects or 3D scaffolds. Overall, they show great promise for numerous applications in biosciences and biotechnology. For instance, practical applications of bioactive surfaces in the fields of bioseparation, cell engineering, biochips and stem-cell differentiation are briefly discussed herein. Y1 - 2010 UR - http://www.rsc.org/Publishing/Journals/sm/index.asp U6 - https://doi.org/10.1039/B913594d SN - 1744-683X ER - TY - JOUR A1 - Couturier, Jean-Philippe A1 - Sütterlin, Martin A1 - Laschewsky, André A1 - Hettrich, Cornelia A1 - Wischerhoff, Erik T1 - Responsive Inverse Opal Hydrogels for the Sensing of Macromolecules JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - Dual responsive inverse opal hydrogels were designed as autonomous sensor systems for (bio)macromolecules, exploiting the analyte-induced modulation of the opal's structural color. The systems that are based on oligo(ethylene glycol) macromonomers additionally incorporate comonomers with various recognition units. They combine a coil-to-globule collapse transition of the LCST type with sensitivity of the transition temperature toward molecular recognition processes. This enables the specific detection of macromolecular analytes, such as glycopolymers and proteins, by simple optical methods. While the inverse opal structure assists the effective diffusion even of large analytes into the photonic crystal, the stimulus responsiveness gives rise to strong shifts of the optical Bragg peak of more than 100nm upon analyte binding at a given temperature. The systems' design provides a versatile platform for the development of easy-to-use, fast, and low-cost sensors for pathogens. KW - hydrogels KW - photonic crystals KW - polymers KW - responsive materials KW - sensors Y1 - 2015 U6 - https://doi.org/10.1002/anie.201500674 SN - 1433-7851 SN - 1521-3773 VL - 54 IS - 22 SP - 6641 EP - 6644 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Buller, Jens A1 - Laschewsky, André A1 - Wischerhoff, Erik T1 - Photoreactive oligoethylene glycol polymers - versatile compounds for surface modification by thin hydrogel films JF - Soft matter N2 - Solid surfaces are modified using photo-crosslinkable copolymers based on oligo(ethylene glycol) methacrylate (OEGMA) bearing 2-(4-benzoylphenoxy) ethyl methacrylate (BPEM) as a photosensitive crosslinking unit. Thin films of about 100 nm are formed by spin-coating these a priori highly biocompatible copolymers onto silicon substrates. Subsequent UV-irradiation assures immobilization and crosslinking of the hydrogel films. Their stability is controlled by the number of crosslinker units per chain and the molar mass of the copolymers. The swelling of the hydrogel layers, as investigated by ellipsometry, can be tuned by the crosslinker content in the copolymer. If films are built from the ternary copolymers of OEGMA, BPEM and 2-(2-methoxyethoxy) ethyl methacrylate (MEO(2)MA), the hydrogel films exhibit a swelling/deswelling transition of the lower critical solution temperature (LCST) type. The observed thermally induced hydrogel collapse is fully reversible and the onset temperature of the transition can be tuned at will by the copolymer composition. Different from analogously prepared thermo-responsive hydrogel films of photocrosslinked poly(N-isopropylacrylamide), the swelling-deswelling transition occurs more gradually, but shows no hysteresis. Y1 - 2013 U6 - https://doi.org/10.1039/c2sm26879e SN - 1744-683X VL - 9 IS - 3 SP - 929 EP - 937 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Arys, Xavier A1 - Fischer, Peter A1 - Jonas, Alain M. A1 - Koetse, Marc M. A1 - Legras, Roger A1 - Laschewsky, André A1 - Wischerhoff, Erik T1 - Ordered polyelectrolyte multilayers : rules governing layering in organic binary multilayers Y1 - 2003 ER - TY - JOUR A1 - Uhlig, Katja A1 - Wischerhoff, Erik A1 - Lutz, Jean-Francois A1 - Laschewsky, André A1 - Jäger, Magnus S. A1 - Lankenau, Andreas A1 - Duschl, Claus T1 - Monitoring cell detachment on PEG-based thermoresponsive surfaces using TIRF microscopy N2 - Recently, we introduced a thermoresponsive copolymer that consists of oligo(ethylene glycol) methacrylate (OEGMA) and 2-(2- methoxyethoxy) ethyl methacrylate (MEO(2)MA). The polymer exhibited an LCST at 35 degrees C in PBS buffer and was anchored onto gold substrates using disulfide polymerisation initiators. It allows the noninvasive detachment of adherent cells from their substrate. As the mechanisms that determine the interaction of cells with such polymers are not well understood, we employed Total Internal Reflection Fluorescence (TIRF) microscopy in order to monitor the detachment process of cells of two different types. We identified contact area and average cell-substrate distance as crucial parameters for the evaluation of the detachment process. The sensitivity of TIRF microscopy allowed us to correlate the specific adhesion pattern of MCF-7 breast cancer cells with the morphology of cell deposits that may serve as fingerprints for a nondestructive characterisation of live cells. Y1 - 2010 UR - http://www.rsc.org/Publishing/Journals/sm/index.asp U6 - https://doi.org/10.1039/C0sm00010h SN - 1744-683X ER - TY - JOUR A1 - Hildebrand, Viet A1 - Laschewsky, Andre A1 - Wischerhoff, Erik T1 - Modulating the solubility of zwitterionic poly((3methacrylamidopropyl)ammonioalkane sulfonate)s in water and aqueous salt solutions via the spacer group separating the cationic and the anionic moieties JF - Polymer Chemistry N2 - Complementary to the well-established zwitterionic monomer 3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SPP), the closely related monomers 2-hydroxy-3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SHPP) and 4-((3-methacrylamidopropyl) dimethylammonio)butane- 1-sulfonate (SBP) were synthesised and polymerised by reversible addition-fragmentation chain transfer (RAFT) polymerisation, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar masses were characterised with respect to their solubility in water and aqueous salt solutions. Both poly(sulfobetaine)s show thermoresponsive behaviour in water, exhibiting phase separation at low temperatures and upper critical solution temperatures (UCST). For both polySHPP and polySBP, cloud points depend notably on the molar mass, and are much higher in D2O than in H2O. Also, the cloud points are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed nature of the spacer group separating the anionic and the cationic charges of the betaine moiety, on the other hand. As anticipated, the cloud points of polySBP are much higher than the ones of the analogous polySPP of identical molar mass. Surprisingly, the cloud points of polySHPP are also somewhat higher than the ones of their polySPP analogues, despite the additional hydrophilic hydroxyl group present in the spacer separating the ammonium and the sulfonate moieties. These findings point to a complicated interplay of the various hydrophilic components in polyzwitterions with respect to their overall hydrophilicity. Thus, the spacer group in the betaine moiety proves to be an effective additional molecular design parameter, apparently small variations of which strongly influence the phase behaviour of the polyzwitterions in specific aqueous environments. Y1 - 2016 U6 - https://doi.org/10.1039/c5py01642h SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 731 EP - 740 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Heydari, Esmaeil A1 - Buller, Jens A1 - Wischerhoff, Erik A1 - Laschewsky, André A1 - Döring, Sebastian A1 - Stumpe, Joachim T1 - Label-Free biosensor based on an all-polymer DFB laser JF - Advanced optical materials KW - label-free biosensors KW - DFB lasers KW - active optical resonators KW - hydrogels KW - semiconducting polymers Y1 - 2014 U6 - https://doi.org/10.1002/adom.201300454 SN - 2195-1071 VL - 2 IS - 2 SP - 137 EP - 141 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Enzenberg, Anne A1 - Laschewsky, Andre A1 - Boeffel, Christine A1 - Wischerhoff, Erik T1 - Influence of the Near Molecular Vicinity on the Temperature Regulated Fluorescence Response of Poly(N-vinylcaprolactam) JF - Polymers N2 - A series of new fluorescent dye bearing monomers, including glycomonomers, based on maleamide and maleic esteramide was synthesized. The dye monomers were incorporated by radical copolymerization into thermo-responsive poly(N‑vinyl-caprolactam) that displays a lower critical solution temperature (LCST) in aqueous solution. The effects of the local molecular environment on the polymers’ luminescence, in particular on the fluorescence intensity and the extent of solvatochromism, were investigated below as well as above the phase transition. By attaching substituents of varying size and polarity in the close vicinity of the fluorophore, and by varying the spacer groups connecting the dyes to the polymer backbone, we explored the underlying structure–property relationships, in order to establish rules for successful sensor designs, e.g., for molecular thermometers. Most importantly, spacer groups of sufficient length separating the fluorophore from the polymer backbone proved to be crucial for obtaining pronounced temperature regulated fluorescence responses. View Full-Text KW - thermo-responsive polymers KW - poly(N-vinylcaprolactam) KW - lower critical solution temperature KW - fluorescent dyemonomers KW - naphthalimide KW - solvatochromism KW - polymeric sensors KW - molecular thermometers Y1 - 2016 U6 - https://doi.org/10.3390/polym8040109 SN - 2073-4360 VL - 8 PB - MDPI CY - Basel ER - TY - JOUR A1 - Cramer, Ashley D. A1 - Gambinossi, Filippo A1 - Wischerhoff, Erik A1 - Laschewsky, André A1 - Miller, Reinhard A1 - Ferri, James K. T1 - Flexible thermoresponsive nanomembranes at the aqueous-air interface JF - Chemical communications N2 - A synthetic pathway is described to construct thermoresponsive freestanding nanomembranes at the aqueous-air interface of a pendant drop. Dynamic control of the reaction kinetics allows formation of viscoelastic interfaces supporting anisotropic stresses and mechanical stability, which can be tuned by external stimuli. Y1 - 2015 U6 - https://doi.org/10.1039/c4cc07359b SN - 1359-7345 SN - 1364-548X VL - 51 IS - 5 SP - 877 EP - 880 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Gambinossi, Filippo A1 - Sefcik, Lauren S. A1 - Wischerhoff, Erik A1 - Laschewsky, André A1 - Ferri, James K. T1 - Engineering Adhesion to Thermoresponsive Substrates: Effect of Polymer Composition on Liquid-Liquid-Solid Wetting JF - ACS applied materials & interfaces N2 - Adhesion control in liquidliquidsolid systems represents a challenge for applications ranging from self-cleaning to biocompatibility of engineered materials. By using responsive polymer chemistry and molecular self-assembly, adhesion at solid/liquid interfaces can be achieved and modulated by external stimuli. Here, we utilize thermosensitive polymeric materials based on random copolymers of di(ethylene glycol) methyl ether methacrylate (x = MEO(2)MA) and oligo(ethylene glycol) methyl ether methacrylate (y = OEGMA), that is, P(MEO(2)MA(x)-co-OEGMA(y)), to investigate the role of hydrophobicity on the phenomenon of adhesion. The copolymer ratio (x/y) dictates macromolecular changes enabling control of the hydrophilic-to-lipophilic balance (HBL) of the polymer brushes through external triggers such as ionic strength and temperature. We discuss the HBL of the thermobrushes in terms of the surface energy of the substrate by measuring the contact angle at waterdecaneP(MEO(2)MA(x)-co-OEGMA(y)) brush contact line as a function of polymer composition and temperature. Solid supported polyelectrolyte layers grafted with P(MEO(2)MA(x)-co-OEGMA(y)) display a transition in the wettability that is related to the lower critical solution temperature of the polymer brushes. Using experimental observation of the hydrophilic to hydrophobic transition by the contact angle, we extract the underlying energetics associated with liquidliquidsolid adhesion as a function of the copolymer ratio. The change in cellular attachment on P(MEO(2)MA(x)-co-OEGMA(y)) substrates of variable (x/y) composition demonstrates the subtle role of compositional tuning on the ability to control liquidliquidsolid adhesion in biological applications. KW - water/decane contact angle KW - thermoresponsive substrates KW - di(ethylene glycol) methy ether methacrylate KW - oligo(ethylene glycol) methyl ether methacrylate KW - hydrophilic-to-lipophilic balance KW - programmable adhesion Y1 - 2015 U6 - https://doi.org/10.1021/am507418m SN - 1944-8244 VL - 7 IS - 4 SP - 2518 EP - 2528 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Fandrich, Artur A1 - Buller, Jens A1 - Wischerhoff, Erik A1 - Laschewsky, André A1 - Lisdat, Fred T1 - Electrochemical detection of the thermally induced phase transition of a thin stimuli-responsive polymer film JF - ChemPhysChem : a European journal of chemical physics and physical chemistry KW - cyclic voltammetry KW - electrochemical impedance spectroscopy KW - polymers KW - surface chemistry KW - surface plasmon resonance Y1 - 2012 U6 - https://doi.org/10.1002/cphc.201100924 SN - 1439-4235 VL - 13 IS - 8 SP - 2020 EP - 2023 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Fandrich, Artur A1 - Buller, Jens A1 - Schäfer, Daniel A1 - Wischerhoff, Erik A1 - Laschewsky, André A1 - Lisdat, Fred T1 - Electrochemical characterization of a responsive macromolecular interface on gold JF - Physica status solidi : A, Applications and materials science N2 - This study reports on the investigation of a thermoresponsive polymer as a thin film on electrodes and the influence of coupling a peptide and an antibody to the film. The utilized polymer from the class of poly(oligoethylene glycol)-methacrylate polymers (poly(OEGMA)) with carboxy functions containing side chains was synthesized and properly characterized in aqueous solutions. The dependence of the cloud point on the pH of the surrounding media is discussed. The responsive polymer was immobilized on gold electrodes as shown by electrochemical, quartz crystal microbalance (QCM), and atomic force microscopy (AFM) techniques. The temperature dependent behavior of the polymer covalently grafted to gold substrates is investigated using cyclic voltammetry (CV) in ferro-/ferricyanide solution. Significant changes in the slope of the temperature-dependence of the voltammetric peak current and the peak separation values clearly indicate the thermally induced conformational change on the surface. Finally, a biorecognition reaction between a short FLAG peptide (N-Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Lys-C) covalently immobilized on the polymer interface and the corresponding IgG antibody was performed. The study shows that the responsiveness of the electrode is retained after peptide coupling and antibody binding, although the response is diminished. KW - biorecognition reactions KW - cyclic voltammetry KW - electrodes KW - gold KW - interfaces KW - responsive polymers Y1 - 2015 U6 - https://doi.org/10.1002/pssa.201431698 SN - 1862-6300 SN - 1862-6319 VL - 212 IS - 6 SP - 1359 EP - 1367 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Laschewsky, André A1 - Mallwitz, Frank A1 - Baussard, Jean-Francois A1 - Cochin, Didier A1 - Fischer, Peter A1 - Habib-Jiwan, Jean-Louis A1 - Wischerhoff, Erik T1 - Aggregation phenomena in polyelectrolyte multilayers made from polyelectrolytes bearing bulky functional, hydrophobic fragments N2 - The functionalization of polyelectrolyte multilayers often implies the use of bulky functional fragments, attached to a standard polyelectrolyte matrix. Despite of the high density of non-charged, often hydrophobic substituents, regular film growth by sequential adsorption proceeds easily when an appropriate polyelectrolyte counter ion is chosen. However, the functional fragments may cluster or aggregate. This complication is particularly evident when using chromophores and fluorophores as bulky pendant groups. Attention has to be paid to this phenomenon for the design of functional polyelectrolyte films, as aggregation may modify crucially the properties. The use of charged spacer groups does not necessarily suppress the aggregation of functional side groups. Still, clustering and aggregation depend on the detailed system employed, and are not obligatory. In the case of cationic poly(acrylamide)s labeled with naphthalene and pyrene fluorophores, for instance, the polymers form intramolecular hydrophobic associates in solution, as indicated by strong excimer formation. But the polymers can undergo a conformational rearrangement upon adsorption so that they are decoiled in the adsorbed films. Analogous observations are made for polyanions bearing mesogenic biphenyls fragments. In contrast, polycations functionalized with the dye coumarin 343 show little aggregation in solution, but a marked aggregation in the ESA films Y1 - 2004 ER -