Peter Miethe

Aerogels from Unaltered Bacterial Cellulose: Application of scCO2 Drying for the Preparation of Shaped, Ultra-Lightweight Cellulosic Aerogels

Bacterial cellulose produced by the gram-negative bacterium Gluconacetobacter xylinum was found to be an excellent native starting material for preparing shaped ultra-lightweight cellulose aerogels. The procedure comprises thorough washing and sterilization of the aquogel, quantitative solvent exchange and subsequent drying with supercritical carbon dioxide at 40 degrees C and 100 bar. The average density of the obtained dry cellulose aerogels is only about 8 mg x cm(-3) which is comparable to the most lightweight silica aerogels and distinctly lower than all values for cellulosic aerogels obtained from plant cellulose so far. SEM, ESEM and nitrogen adsorption experiments at 77 K reveal an open-porous network structure that consists of a comparatively high percentage of large mesopores and smaller macropores.

Solid-state fermentation of lignocellulotic materials for the production of enzymes by the white-rot fungus Trametes hirsuta in a modular bioreactor

Trametes hirsuta, a filamentous basidiomycete, was successfully cultivated in solid‐state fermentation (SSF) on a mixture of pine wood chips and orange peel in a novel bioreactor that allows mixing of the inoculated solid material during the fermentation. Copper sulfate or xylidine (2,5‐dimethylaniline) were added to enhance the production of enzymes, especially laccases. For comparison, Trametes hirsuta was also cultivated in submerged conditions. The effect of additives in SSF was low, whereas the choice of the solid material and the rotation of the reactor vessel showed a significant influence on the enzyme production. The space‐time yields for the fermentations were calculated and showed that SSF on low‐cost substrates can effectively produce extracellular enzymes at a sufficient rate by a cultivation method that requires only low technology equipment.

Rapid flow through immunoassay for CRP determination based on polyethylene filters modified with ω-aminocellulose carbamate.

A novel method for antibody immobilization is discussed and applied in a column based flow through immunoassay system (ABICAP). It is shown that porous polyethylene material can be modified with different ω-aminocellulose carbamates yielding an amino group containing biocompatible support for antibody immobilization. Anti-h CRP antibodies can be bound covalently to the surface via various homobifunctional cross-linkers. The antibody modified filters are validated for the CRP determination in a sandwich ABICAP system. In a 10 min test procedure based on colloidal dye particles, a limit of detection of 5 ng CRP mL(-1) and coefficients of variation of <9.1% are obtained.