TY - JOUR A1 - Frasca, Stefano A1 - Richter, Claudia A1 - von Graberg, Till A1 - Smarsly, Bernd M. A1 - Wollenberger, Ursula T1 - Electrochemical switchable protein-based optical device JF - Engineering in life sciences : Industry, Environment, Plant, Food N2 - The present work contributes to the development of reusable sensing systems with a visual evaluation of the detection process related to an analyte. An electrochemical switchable protein-based optical device was designed with the core part composed of cytochrome c immobilized in a mesoporous indium tin oxide film. A color-developing redox-sensitive dye was used as switchable component of the system. The cytochrome c-catalyzed oxidation of the dye by hydrogen peroxide is spectroscopically investigated. When the dye is co-immobilized with the protein, its redox state is easily controlled by application of an electrical potential at the supporting material. This enables to electrochemically reset the system to the initial state and repetitive signal generation. The implemented reset function of the color forming reaction will make calibration of small test devices possible. The principle can be extended to other color forming redox reactions and to coupled enzyme systems, such as rapid food testing and indication of critical concentrations of metabolites for health care. KW - Cytochrome c KW - Electrochemical switch KW - Indium tin oxide KW - mesoporous materials KW - Optical device Y1 - 2011 U6 - https://doi.org/10.1002/elsc.201100079 SN - 1618-0240 VL - 11 IS - 6 SP - 554 EP - 558 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Goebel, Ronald A1 - Hesemann, Peter A1 - Friedrich, Alwin A1 - Rothe, Regina A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Modular thiol-ene chemistry approach towards mesoporous silica monoliths with organically modified pore walls JF - Chemistry - a European journal N2 - The surface modification of mesoporous silica monoliths through thiol-ene chemistry is reported. First, mesoporous silica monoliths with vinyl, allyl, and thiol groups were synthesized through a sol-gel hydrolysis-poly-condensation reaction from tetramethyl orthosilicate (TMOS) and vinyltriethoxysilane, allyltriethoxysilane, and (3-mercaptopropyl) trimethoxysilane, respectively. By variation of the molar ratio of the comonomers TMOS and functional silane, mesoporous silica objects containing different amounts of vinyl, allyl, and thiol groups were obtained. These intermediates can subsequently be derivatized through radical photoaddition reactions either with a thiol or an olefin, depending on the initial pore wall functionality, to yield silica monoliths with different pore-wall chemistries. Nitrogen sorption, small-angle X-ray scattering, solid-state NMR spectroscopy, elemental analysis, thermogravimetric analysis, and redox titration demonstrate that the synthetic pathway influences the morphology and pore characteristics of the resulting monoliths and also plays a significant role in the efficiency of functionalization. Moreover, the different reactivity of the vinyl and allyl groups on the pore wall affects the addition reaction, and hence, the degree of the pore-wall functionalization. This report demonstrates that thiol-ene photoaddition reactions are a versatile platform for the generation of a large variety of organically modified silica monoliths with different pore surfaces. KW - mesoporous materials KW - photochemistry KW - sol-gel processes KW - surface chemistry Y1 - 2014 U6 - https://doi.org/10.1002/chem.201403982 SN - 0947-6539 SN - 1521-3765 VL - 20 IS - 52 SP - 17579 EP - 17589 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Neumann, Bettina A1 - Kielb, Patrycja A1 - Rustam, Lina A1 - Fischer, Anna A1 - Weidinger, Inez M. A1 - Wollenberger, Ulla T1 - Bioelectrocatalytic Reduction of Hydrogen Peroxide by Microperoxidase-11 Immobilized on Mesoporous Antimony-Doped Tin Oxide JF - ChemElectrChem N2 - The heme-undecapeptide microperoxidase-11 (MP-11) was immobilized on mesoporous antimony-doped tin oxide (ATO) thin-film electrodes modified with the positively charged binding promotor polydiallyldimethylammonium chloride. Surface concentrations of MP-11 of 1.5 nmol cm(-2) were sufficiently high to enable spectroelectrochemical analyses. UV/Vis spectroscopy and resonance Raman spectroscopy revealed that immobilized MP-11 adopts a six-coordinated low-spin conformation, as in solution in the presence of a polycation. Cathodic reduction of hydrogen peroxide at potentials close to +500mV versus Ag/AgCl indicates that the reaction proceeds via a Compound I-type like intermediate, analogous to natural peroxidases, and confirms mesoporous ATO as a suitable host material for adsorbing the heme-peptide in its native state. A hydrogen peroxide sensor is proposed by using the bioelectrocatalytic properties of the MP-11-modified ATO. KW - electrochemistry KW - enzyme catalysis KW - mesoporous materials KW - microperoxidase KW - spectroelectrochemistry Y1 - 2017 U6 - https://doi.org/10.1002/celc.201600776 SN - 2196-0216 VL - 4 IS - 4 SP - 913 EP - 919 PB - Wiley-VCH CY - Weinheim ER - TY - THES A1 - Voß, Rebecca T1 - Mesoporous organosilica materials with amine functions : surface characteristics and chirality T1 - Mesoporöse Amin-funktionalisierte Organo-Silik ate : Oberflächen Eigenschaften und Chiralität N2 - In this work mesoporous organisilica materials are synthesized through the silica sol-gel process. For this a new class of precursors which are also surfactant are synthesized and self-assembled. This leads to a high surface area functionality which is analysized with copper (II) and water adsorption. N2 - Im Rahmen dieser Arbeit werden mesoporöse Amin-funktionalisierte Organo-Silikate durch den Silika Sol-Gel Prozess hergestellt. Dabei werden neue Alkoxysilyl-Precursoren synthetisiert und condensiert die die gewünschte Funktion auf die Oberfläche dirigieren. Herstellt werden primäre, secundäre und chirale Amine. Die Oberflächenfunktionalität wird mit Kupfer (II) und Wasser Adsorption analysiert. T2 - Mesoporous organosilica materials with amine functions : surface characteristics and chirality KW - Silicate KW - Chiralität KW - Adsorption KW - Poröser Stoff KW - Hydroborierung KW - Amine KW - Mesoporöse Materialien KW - Organo-Silikate KW - mesoporous materials KW - organosilica Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5287 ER -