Doctor of Philosophy, Eidgenossische Technische Hochschule (ETH Zurich) (2012)
Master of Science, Eidgenossische Technische Hochschule (ETH Zurich) (2009)
Bachelor of Science, Eidgenossische Technische Hochschule (ETH Zurich) (2007)
Ferromagnetic Inks Facilitate Large Scale Paper Recycling and Reduce Bleach Chemical Consumption
2013; 29 (16): 5093-5098
Deinking is a fundamental part of paper recycling. As the global paper consumption rises and exceeds even the annual paper production, recycling of this raw material is of high importance. Magnetic ink based on carbon coated magnetic nanoparticles enables an alternative approach to state of the art paper deinking. Magnetic deinking comprises three steps (preselection, washing, and magnetic separation of fibers). Preseparation of printed from nonprinted scraps of paper is feasible and reduces the paper mass which has to be fed into a deinking process. A consecutive washing process removes surficial magnetic ink that can be collected by application of a permanent magnet. Still, printed parts are subjected to a further continuous magnetic deinking step, where magnetic and nonmagnetic paper fibers can be separated. Magnetic deinking of a model print allows recovery of more than 80% of bright fibers without any harsh chemical treatment and the re-collection of more than 82% of magnetic ink.
View details for DOI 10.1021/la400165v
View details for Web of Science ID 000318143600020
View details for PubMedID 23495668
Thermoresponsive Polymer Induced Sweating Surfaces as an Efficient Way to Passively Cool Buildings
2012; 24 (39): 5352-5356
Buildings can be effectively cooled by a bioinspired sweating-like action based on thermoresponsive hydrogels (PNIPAM), which press out their stored water when exceeding the lower critical solution temperature. The surface temperature is reduced by 15 °C compared to that of a conventional hydrogel (pHEMA) and by 25 °C compared to the bare ground.
View details for DOI 10.1002/adma.201202574
View details for Web of Science ID 000309405200008
View details for PubMedID 22933383
Incorporating microorganisms into polymer layers provides bioinspired functional living materials
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2012; 109 (1): 90-94
Artificial two-dimensional biological habitats were prepared from porous polymer layers and inoculated with the fungus Penicillium roqueforti to provide a living material. Such composites of classical industrial ingredients and living microorganisms can provide a novel form of functional or smart materials with capability for evolutionary adaptation. This allows realization of most complex responses to environmental stimuli. As a conceptual design, we prepared a material surface with self-cleaning capability when subjected to standardized food spill. Fungal growth and reproduction were observed in between two specifically adapted polymer layers. Gas exchange for breathing and transport of nutrient through a nano-porous top layer allowed selective intake of food whilst limiting the microorganism to dwell exclusively in between a confined, well-enclosed area of the material. We demonstrated a design of such living materials and showed both active (eating) and waiting (dormant, hibernation) states with additional recovery for reinitiation of a new active state by observing the metabolic activity over two full nutrition cycles of the living material (active, hibernation, reactivation). This novel class of living materials can be expected to provide nonclassical solutions in consumer goods such as packaging, indoor surfaces, and in biotechnology.
View details for DOI 10.1073/pnas.1115381109
View details for Web of Science ID 000298876500024
View details for PubMedID 22198770
Phosphate starvation as an antimicrobial strategy: the controllable toxicity of lanthanum oxide nanoparticles
2012; 48 (32): 3869-3871
Lanthanum oxide nanoparticles were utilized to scavenge phosphate from microbial growth media for the use of targeted nutrient starvation as an antimicrobial strategy. Only in phosphate poor environments a toxic effect was observed. The effect was shown on Escherichia coli, Staphylococcus carnosus, Penicillium roqueforti, and Chlorella vulgaris.
View details for DOI 10.1039/c2cc30903c
View details for Web of Science ID 000301956700023
View details for PubMedID 22410707
Incorporation of Penicillin-Producing Fungi into Living Materials to Provide Chemically Active and Antibiotic-Releasing Surfaces
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
2012; 51 (45): 11293-11296
Living materials: artificial biological niches are loaded with the penicillin-producing mold Penicillium chrysogenum. This living material consumes food through a nanoporous top layer and releases the antibiotic on-site. No reloading of the active compound is needed. Gram-positive bacteria were efficiently killed if nearby, whereas Gram-negative bacteria (control experiment, not sensitive to penicillin) were not affected.
View details for DOI 10.1002/anie.201204337
View details for Web of Science ID 000310874400019
View details for PubMedID 23044633
Incorporation of Reactive Silver-Tricalcium Phosphate Nanoparticles Into Polyamide 6 Allows Preparation of Self-Disinfecting Fibers
POLYMER ENGINEERING AND SCIENCE
2011; 51 (1): 71-77
View details for Web of Science ID 000285903600008
Nanoparticle cytotoxicity depends on intracellular solubility: Comparison of stabilized copper metal and degradable copper oxide nanoparticles
2010; 197 (3): 169-174
Metal nanoparticles have distinctly different chemical and physical properties than currently investigated oxides. Since pure metallic nanoparticles are igniting at air, carbon stabilized copper nanoparticles were used as representative material for this class. Using copper as a representative example, we compare the cytotoxicity of copper metal nanoparticles stabilized by a carbon layer to copper oxide nanoparticles using two different cell lines. Keeping the copper exposure dose constant, the two forms of copper showed a distinctly different response. Whilst copper oxide had already been reported to be highly cytotoxic, carbon-coated copper nanoparticles were much less cytotoxic and more tolerated. Measuring the two material's intra- and extracellular solubility in model buffers explained this difference on the basis of altered copper release when supplying copper metal or the corresponding oxide particles to the cells. Control experiments using pure carbon nanoparticles were used to exclude significant surface effects. Reference experiments with ionic copper solutions confirmed a similar response of cultures if exposed to copper oxide nanoparticles or ionic copper. These observations are in line with a Trojan horse-type mechanism and illustrate the dominating influence of physico-chemical parameters on the cytotoxicity of a given metal.
View details for DOI 10.1016/j.toxlet.2010.05.012
View details for Web of Science ID 000281002700003
View details for PubMedID 20621582