Olga Mergel
RWTH Aachen University
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Featured researches published by Olga Mergel.
Biomacromolecules | 2014
Larisa V. Sigolaeva; Snezhana Yu. Gladyr; Arjan P. H. Gelissen; Olga Mergel; Dmitry V. Pergushov; Ilya N. Kurochkin; Felix A. Plamper; Walter Richtering
This work examines the fabrication regime and the properties of microgel and microgel/enzyme thin films adsorbed onto conductive substrates (graphite or gold). The films were formed via two sequential steps: the adsorption of a temperature- and pH-sensitive microgel synthesized by precipitation copolymerization of N-isopropylacrylamide (NIPAM) and 3-(N,N-dimethylamino)propylmethacrylamide (DMAPMA) (poly(NIPAM-co-DMAPMA) at the pH-condition corresponding to its noncharged state (first step of adsorption), followed by the enzyme, tyrosinase, adsorption at the pH-condition when the microgel and the enzyme are oppositely charged (second step of adsorption). The stimuli-sensitive properties of poly(NIPAM-co-DMAPMA) microgel were characterized by potentiometric titration and dynamic light scattering (DLS) in solution as well as by atomic force microscopy (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D) at solid interface. Enhanced deposition of poly(NIPAM-co-DMAPMA) microgel particles was shown at elevated temperatures exceeding the volume phase transition temperature (VPTT). The subsequent electrostatic interaction of the poly(NIPAM-co-DMAPMA) microgel matrix with tyrosinase was examined at different adsorption regimes. A considerable increase in the amount of the adsorbed enzyme was detected when the microgel film is first brought into a collapsed state but then was allowed to interact with the enzyme at T < VPTT. Spongelike approach to enzyme adsorption was applied for modification of screen-printed graphite electrodes by poly(NIPAM-co-DMAPMA)/tyrosinase films and the resultant biosensors for phenol were tested amperometrically. By temperature-induced stimulating both (i) poly(NIPAM-co-DMAPMA) microgel adsorption at T > VPTT and (ii) following spongelike tyrosinase loading at T < VPTT, we can achieve more than 3.5-fold increase in biosensor sensitivity for phenol assay. Thus, a very simple, novel, and fast strategy for physical entrapment of biomolecules by the polymeric matrix was proposed and tested. Being based on this unique stimuli-sensitive behavior of the microgel, this stimulated spongelike adsorption provides polymer films comprising concentrated biomaterial.
Langmuir | 2015
Larisa V. Sigolaeva; Olga Mergel; Evgeniy G. Evtushenko; Snezhana Yu. Gladyr; Arjan P. H. Gelissen; Dmitry V. Pergushov; Ilya N. Kurochkin; Felix A. Plamper; Walter Richtering
This work examines the adsorption regime and the properties of microgel/enzyme thin films deposited onto conductive graphite-based substrates. The films were formed via two-step sequential adsorption. A temperature- and pH-sensitive poly(N-isopropylacrylamide)-co-(3-(N,N-dimethylamino)propylmethacrylamide) microgel (poly(NIPAM-co-DMAPMA microgel) was adsorbed first, followed by its interaction with the enzymes, choline oxidase (ChO), butyrylcholinesterase (BChE), or mixtures thereof. By temperature-induced stimulating both (i) poly(NIPAM-co-DMAPMA) microgel adsorption at T > VPTT followed by short washing and drying and then (ii) enzyme loading at T < VPTT, we can effectively control the amount of the microgel adsorbed on a hydrophobic interface as well as the amount and the spatial localization of the enzyme interacted with the microgel film. Depending on the biomolecule size, enzyme molecules can (in the case for ChO) or cannot (in the case for BChE) penetrate into the microgel interior and be localized inside/outside the microgel particles. Different spatial localization, however, does not affect the specific enzymatic responses of ChO or BChE and does not prevent cascade enzymatic reaction involving both BChE and ChO as well. This was shown by the methods of electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), and amperometric analysis of enzymatic responses of immobilized enzymes. Thus, a novel simple and fast strategy for physical entrapment of biomolecules by the polymeric matrix was proposed, which can be used for engineering systems with spatially separated enzymes of different types.
Nanomedicine: Nanotechnology, Biology and Medicine | 2017
A. A. Yaroslavov; I. G. Panova; Andrey V. Sybachin; Vasiliy V. Spiridonov; Alexander B. Zezin; Olga Mergel; Arjan P. H. Gelissen; Rahul Tiwari; Felix A. Plamper; Walter Richtering; Fredric M. Menger
Abstract We present a smart liposome carrier system for stimulated release, consisting of cationic, thermo-responsive microgels. At low temperature, the swollen microgels adsorb about 200 anionic liposomes, 50 nm in diameter, per microgel. When heated from 39 °C to 41 °C, the microgel–liposome complex particles collapse from approx. 370 nm down to approx. 270 nm. Upon the thermo-induced collapse, the adsorbed liposome satellite layer is squeezed until the initially spherical liposomes explode and release their payload (antitumor drug doxorubicin) into the surrounding. This burst release mechanism, taking place over a narrow temperature range, is newly reported and of possible biomedical importance.
Analytical Chemistry | 2017
Larisa V. Sigolaeva; Snezhana Yu. Gladyr; Olga Mergel; Arjan P. H. Gelissen; Michael Noyong; Ulrich Simon; Dmitry V. Pergushov; Ilya N. Kurochkin; Felix A. Plamper; Walter Richtering
A versatile guest matrix was fabricated from a temperature- and pH-sensitive poly(N-isopropylacrylamide)-co-(3-(N,N-dimethylamino)propylmethacrylamide) microgel (poly(NIPAM-co-DMAPMA), MG) for the gentle incorporation of butyrylcholinesterase (BChE). The microgel/BChE films were built up on a surface of graphite-based screen-printed electrodes (SPEs) premodified with MnO2 nanoparticles via a two-step sequential adsorption under careful temperature and pH control. On this basis, a rather simple amperometric biosensor construct was formed, which uses butyrylthiocholine as BChE substrate with subsequent MnO2-mediated thiocholine oxidation at a graphite-based SPE. The complexation of BChE with the microgel was found to be safe and effective, as confirmed by a high operational and rather good long-term storage stability of the resultant SPE-MnO2/MG/BChE biosensors. The small mesh size of the microgel with respect to the size of BChE results in a predominant outer complexation of BChE within the dangling chains of the microgel rather than a deep penetration of the enzyme into the microgels. Given such surface localization, BChE is easily accessible both for the substrate and for cholinesterase inhibitors. This was supported by the analytical characteristics of the SPE-MnO2/MG/BChE biosensor that were examined and optimized both for the substrate and for the enzyme detection. The SPE-MnO2/MG/BChE biosensor enabled precision detection of organophosphorus pesticides (diazinon(oxon), chlorpyrifos(oxon)) in aqueous samples with minimized interference from extraneous (nonanalyte) substances (e.g., ions of heavy metals). The detection limits for diazinon(oxon) and chlorpyrifos(oxon) were estimated to be as low as 6 × 10-12 M and 8 × 10-12 M, respectively, after 20 min of preincubation with these irreversible inhibitors of BChE.
Polymers | 2018
Sabine Schneider; Corinna Janssen; Elisabeth Klindtworth; Olga Mergel; Martin Möller; Felix A. Plamper
The effect of polyelectrolyte composition on the electrodeposition onto platinum is investigated using a counterion switching approach. Film formation of preformed polyelectrolytes is triggered by oxidation of hexacyanoferrates(II) (ferrocyanide), leading to polyelectrolyte complexes, which are physically crosslinked by hexacyanoferrate(III) (ferricyanide) ions due to preferential ferricyanide/polycation interactions. In this study, the electrodeposition of three different linear polyelectrolytes, namely quaternized poly[2-(dimethylamino)ethyl methacrylate] (i.e., poly{[2-(methacryloyloxy)ethyl]trimethylammonium chloride}; PMOTAC), quaternized poly[2-(dimethylamino)ethyl acrylate] (i.e., poly{[2-(acryloyloxy)ethyl]trimethylammonium chloride}; POTAC), quaternized poly[N-(3-dimethylaminopropyl)methacrylamide] (i.e., poly{[3-(methacrylamido)propyl]trimethylammonium chloride}; PMAPTAC) and different statistical copolymers of these polyelectrolytes with N-(3-aminopropyl)methacrylamide (APMA), are studied. Hydrodynamic voltammetry utilizing a rotating ring disk electrode (RRDE) shows the highest deposition efficiency DE for PMOTAC over PMAPTAC and over POTAC. Increasing incorporation of APMA weakens the preferred interaction of the quaternized units with the hexacyanoferrate(III) ions. At a sufficient APMA content, electrodeposition can thus be prevented. Additional electrochemical quartz crystal microbalance measurements reveal the formation of rigid polyelectrolyte films being highly crosslinked by the hexacyanoferrate(III) ions. Results indicate a different degree of water incorporation into these polyelectrolyte films. Hence, by adjusting the polycation composition, film properties can be tuned, while different chemistries can be incorporated into these electrodeposited thin hydrogel films.
Chemistry: A European Journal | 2010
Markus Albrecht; Michael Müller; Olga Mergel; Kari Rissanen; Arto Valkonen
Macromolecules | 2012
Felix A. Plamper; Alexander A. Steinschulte; Christian H. Hofmann; Natascha Drude; Olga Mergel; Christian Herbert; Michael Erberich; Bjoern Schulte; Roland Winter; Walter Richtering
Chemistry of Materials | 2015
Olga Mergel; Patrick Wünnemann; Ulrich Simon; Alexander Böker; Felix A. Plamper
Journal of Physical Chemistry C | 2014
Olga Mergel; Arjan P. H. Gelissen; Patrick Wünnemann; Alexander Böker; Ulrich Simon; Felix A. Plamper
Electrochimica Acta | 2017
Olga Mergel; Philipp T. Kuhn; Sabine Schneider; Ulrich Simon; Felix A. Plampera