Zdenka Maderova

Microwave Assisted Synthesis of Magnetically Responsive Composite Materials

One-pot, microwave-assisted synthesis of various types of magnetically responsive materials from non-magnetic precursors has been developed. The preparation is based on the microwave irradiation of the suspension of the treated material with iron(II) hydroxide prepared by alkalization of iron(II) sulfate. Submicrometer magnetic particles formed during the microwave treatment deposited on the surface of the treated materials in the form of individual particles and their aggregates. The prepared magnetically responsive materials have been used as adsorbents for xenobiotics removal and as carriers for enzymes immobilization.

Magnetically responsive yeast cells: methods of preparation and applications

Magnetically modified yeast cells represent an interesting type of biocomposite material, applicable in various areas of bioanalysis, biotechnology and environmental technology. In this review, typical examples of magnetic modifications of yeast cells of the genera Saccharomyces, Kluyveromyces, Rhodotorula and Yarrowia are presented, as well as their possible applications as biocatalysts, active part of biosensors and biosorbents for the separation of organic xenobiotics, heavy metal ions and radionuclides. Copyright

Utilization of magnetically responsive cereal by-product for organic dye removal.

BACKGROUND Barley straw, an agricultural by-product, can also serve as a low-cost and relatively efficient adsorbent of various harmful compounds. In this case, adsorption of four water-soluble dyes belonging to different dye classes (specifically Bismarck brown Y, representing the azo group; methylene blue, quinone-imine group; safranin O, safranin group; and crystal violet, triphenylmethane group) on native and citric acid-NaOH-modified barley straw, both in magnetic and non-magnetic versions, was studied. RESULTS The adsorption was characterized using three adsorption models, namely Langmuir, Freundlich and Sips. To compare the maximum adsorption capacities (qmax), the Langmuir model was employed. The qmax values reached 86.5-124.3 mg of dye per g of native non-magnetic straw and 410.8-520.3 mg of dye per g of magnetic chemically modified straw. Performed characterization studies suggested that the substantial increase in qmax values after chemical modification could be caused by rougher surface of adsorbent (observed by scanning electron microscopy) and by the presence of higher amounts of carboxyl groups (detected by Fourier transform infrared spectroscopy). The adsorption processes followed the pseudo-second-order kinetic model and thermodynamic studies indicated spontaneous and endothermic adsorption. CONCLUSION The chemical modification of barley straw led to a significant increase in maximum adsorption capacities for all tested dyes, while magnetic modification substantially facilitated the manipulation with adsorbent.

Microwave‐synthesized magnetic chitosan microparticles for the immobilization of yeast cells

An extremely simple procedure has been developed for the immobilization of Saccharomyces cerevisiae cells on magnetic chitosan microparticles. The magnetic carrier was prepared using an inexpensive, simple, rapid, one‐pot process, based on the microwave irradiation of chitosan and ferrous sulphate at high pH. Immobilized yeast cells have been used for sucrose hydrolysis, hydrogen peroxide decomposition and the adsorption of selected dyes. Copyright

Biosorption of Uranium by Magnetically Modified Wheat Bran

The wheat bran was magnetically modified with microwave-synthesized magnetic iron oxides particles. Magnetic wheat bran was chosen as a biosorbent for removal of uranium from aqueous solutions. The uranium sorption increased with increasing pH and reached a plateau between pH 4.0 and 10.0. The increase of temperature slightly improved the sorption process. The uranium adsorption followed the Langmuir adsorption isotherm.

CHAPTER 10:Magnetic Decoration and Labeling of Prokaryotic and Eukaryotic Cells

The majority of prokaryotic and eukaryotic cells can interact with a wide range of magnetic nano- and microparticles, molecular labels or paramagnetic cations. The magnetically modified cells usually maintain their viability and the presence of magnetic (nano)materials on their surfaces, in protoplasm or in intracellular organelles can provide additional functionalities. Magnetically responsive cells can be easily separated from complex samples using magnetic separators, can be monitored using magnetic resonance imaging or heated during magnetic-fluid hyperthermia. Available magnetization procedures are summarized in this chapter, as well as possible efficient applications of magnetically modified cells in cell biology, medicine, bioanalaysis, biotechnology and environmental technology, for example as whole-cell biocatalysts, parts of biosensor systems or adsorbents of organic and inorganic xenobiotics removal.

Decrease of Pseudomonas aeruginosa biofilm formation by food waste materials

The formation of bacterial biofilm on various surfaces has significant negative economic effects. The aim of this study was to find a simple procedure to decrease the Pseudomonas aeruginosa biofilm formation in a water environment by using different food waste biological materials as signal molecule adsorbents. The selected biomaterials did not reduce the cell growth but affected biofilm formation. Promising biomaterials were magnetically modified in order to simplify manipulation and facilitate their magnetic separation. The best biocomposite, magnetically modified spent grain, exhibited substantial adsorption of signal molecules and decreased the biofilm formation. These results suggest that selected food waste materials and their magnetically responsive derivatives could be applied to solve biofilm problems in water environment.

Spent Rooibos (Aspalathus linearis) Tea Biomass as an Adsorbent for Organic Dye Removal

ABSTRACT Spent rooibos (Aspalathus linearis) tea biomass can be used as an inexpensive biosorbent for xenobiotic removal. Seventeen dyes have been tested for their affinity to spent rooibos tea biomass. Eight dyes were used to study the adsorption process in detail. The dye adsorption has been described with the Langmuir isotherm. The calculated maximum adsorption capacities reached the value of over 200 mg of dye per gram of dried rooibos biomass for Bismarck brown Y. Spent rooibos tea biomass was also magnetically modified by contact with microwave-synthesized magnetic iron oxide nano- and microparticles. This new type of magnetically responsive biocomposite material can be easily separated by means of strong permanent magnets. Both native and magnetically modified spent rooibos biomass have shown excellent adsorption capacities for various types of organic dyes, so they are highly promising adsorbents in environmental technologies for selected xenobiotic removal.