Institut für Chemie und Bioanalytik
Dauerhafte URI für die Sammlunghttps://irf.fhnw.ch/handle/11654/24
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Ergebnisse nach Hochschule und Institut
Publikation Magnetic superbasic proton sponges are readily removed and permit direct product isolation(American Chemical Society, 2014) Schneider, Elia M.; Raso, Renzo; Hofer, Corinne J.; Zeltner, Martin; Stettler, Robert D.; Hess, Samuel C.; Grass, Robert N.; Stark, Wendelin J.Workup in organic synthesis can be very time-consuming, particularly when using reagents with both a solubility similar to that of the desired products and a tendency not to crystallize. In this respect, reactions involving organic bases would strongly benefit from a tremendously simplified separation process. Therefore, we synthesized a derivative of the superbasic proton sponge 1,8-bis(dimethylamino)naphthalene (DMAN) and covalently linked it to the strongest currently available nanomagnets based on carbon-coated cobalt metal nanoparticles. The immobilized magnetic superbase reagent was tested in Knoevenagel- and Claisen-Schmidt-type condensations and showed conversions of up to 99%. High yields of up to 97% isolated product could be obtained by simple recrystallization without using column chromatography. Recycling the catalyst was simple and fast with an insignificant decrease in catalytic activity.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Nanoparticle-assisted, catalytic etching of carbon surfaces as a method to manufacture nanogrooves(American Chemical Society, 2012) Schumacher, Christoph M.; Koehler, Fabian M.; Rotzetter, Aline C. C.; Raso, Renzo; Stark, Wendelin J.A simple structuring method for graphitic structures based on the catalytic properties of cerium oxide nanoparticles under oxidizing conditions is presented. Highly oriented pyrolytic graphite chips were impregnated with well-dispersed ceria nanoparticles and then treated at elevated temperatures for several hours. Oxidation activities on the particle surface appeared as crystallographically independent traces that were formed on the graphite and provide a simple method to manufacture nanogrooves at large scale. By altering treatment durations and temperatures, the optimal conditions and activity parameters of the particles were determined. A systematic AFM evaluation allowed formulating of a mechanism of the etching process. The findings provide a simple procedure for the patterning of graphitic structures, formation of nanogrooves and thereby a basic tool for material science with respect to the manufacturing of atmospheric nanofilters and ion-selective membranes.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Plasmonic photothermal activation of an organosilica shielded cold-adapted lipase co-immobilised with gold nanoparticles on silica particles(Royal Society of Chemistry, 01.01.2023) Giunta, Carolina; Nazemi, Seyed Amirabbas; Olesińska, Magdalena; Shahgaldian, PatrickGold nanoparticles (AuNPs), owing to their intrinsic plasmonic properties, are widely used in applications ranging from nanotechnology and nanomedicine to catalysis and bioimaging. Capitalising on the ability of AuNPs to generate nanoscale heat upon optical excitation, we designed a nanobiocatalyst with enhanced cryophilic properties. It consists of gold nanoparticles and enzyme molecules, co-immobilised onto a silica scaffold, and shielded within a nanometre-thin organosilica layer. To produce such a hybrid system, we developed and optimized a synthetic method allowing efficient AuNP covalent immobilisation on the surface of silica particles (SPs). Our procedure allows to reach a dense and homogeneous AuNP surface coverage. After enzyme co-immobilisation, a nanometre-thin organosilica layer was grown on the surface of the SPs. This layer was designed to fulfil the dual function of protecting the enzyme from the surrounding environment and allowing the confinement, at the nanometre scale, of the heat diffusing from the AuNPs after surface plasmon resonance photothermal activation. To establish this proof of concept, we used an industrially relevant lipase enzyme, namely Lipase B from Candida Antarctica (CalB). Herein, we demonstrate the possibility to photothermally activate the so-engineered enzymes at temperatures as low as −10 °C.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Enzyme Armoring by an Organosilica Layer: Synthesis and Characterization of Hybrid Organic/Inorganic Nanobiocatalysts(Academic Press, 02/2017) Correro, Maria Rita; Sykora, Sabine; Corvini, Philippe; Shahgaldian, PatrickThe availability of highly stable and reusable enzymes is one of the main challenges in bio-based industrial processes. Enzyme immobilization and encapsulation represent promising strategies to reach this goal. In this chapter, the synthetic strategy to produce hybrid organic/inorganic nanobiocatalysts (NBC) is reported. This strategy is based on the sequential immobilization of an enzyme on the surface of silica nanoparticles followed by the growth, at the surface of the nanoparticles, of a shielding layer which serves as an armor to protect the enzyme against denaturation/degradation. This armor is produced through a thickness-controlled organosilane poly-condensation onto the nanoparticle surface around the enzyme to form a protective organosilica layer. The armored nanobiocatalysts present enhanced catalytic activity and improved stability against heat, pH, chaotropic agents, proteases, and ultrasound. The method is versatile in that it can be successfully adapted to a number of different enzymes.01A - Beitrag in wissenschaftlicher Zeitschrift