Marta Ziegler-Borowska

Thermal stability of magnetic nanoparticles coated by blends of modified chitosan and poly(quaternary ammonium) salt

Magnetite nanoparticles (Fe3O4 NPs) coated by modified chitosan (m-CS) rich of amino groups and its mixture with poly[N-benzyl-2-(methacryloxy)-N,N-dimethylethanaminium bromide] (PQ) with various mass ratios were prepared by co-precipitation method. The thermal stability of magnetic materials has been investigated by thermogravimetric analysis (TG/DTG/DTA) in air and nitrogen atmosphere. It was found that magnetic NPs coated by polymer blend were characterized by lower thermal stability than protected only by alone CS or m-CS. Magnetite NPs enhance thermooxidative degradation of polymers, however, the stable surface layer, formed from polymer degradation products, efficiently protects the magnetite transformation at higher temperatures. The content of magnetite in obtained systems has been also determined from TG curves.

Ligand fishing using new chitosan based functionalized Androgen Receptor magnetic particles

Superparamagnetic nanoparticles with chemically modified chitosan has been proposed as a potential support for the immobilization of the androgen receptor (AR). The study involved comparison of different AR carriers like commercially available magnetic beads coated with silica (BcMag) and chitosan coated nanoparticles with different amount of amino groups. The immobilization was carried out through covalent immobilization of the AR through the terminal amino group or through available carboxylic acids. The initial characterization of the AR coated magnetic beads was carried out with dihydrotestosterone, a known AR ligand. Subsequently, chitosan modified nanporticles with long-distanced primary amino groups (Fe3O4CS-(NH2)3) (upto 8.34mM/g) were used for further study to isolate known AR ligands (bicalutamide, flutamide, hydroxyflutamide and levonogestrel) from a mixture of tested compounds in ammonium acetate buffer [10mM, pH 7.4]. The results showed that the selected nanoparticles are a promising semi-quantitative tool for the identification of high affinity compounds to AR and might be of special importance in the identification of novel agonists or antiandrogens.

Synthesis and biocidal activity of novel N-halamine hydantoin-containing polystyrenes

Abstract Three homopolymers containing hydantoin substituents were obtained by chemical modification of reactive p-chloromethylated polystyrene. The prepared polymers were chlorinated to yield N-halamine materials with biocidal properties. The chemical structure of polymers was characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. All of the hydantoin polymers are insoluble in water and common organic solvents. Microbiological investigations prove the high biocidal activity of the obtained chlorinated polystyrene derivatives containing spirohydantoin moieties. The obtained polymers will be useful in designing and constructing medical and pharmaceutical equipment. The ability to crosslink allows to expect easy grafting of these biocidal macrochains, for example, on textiles.

Thermal properties of novel polymers based on poly(hydantoin-methyl-p-styrene) and their substrates

The following compounds have been synthesized: (a) hydantoins 5,5-dimethylimidazolidine-2,4-dione (1), 1′,3′-dihydrospiro[imidazolidine-4,2′-indene]-2,5-dione (2), 3′,4′-dihydro-1′H-spiro[imidazolidine-4,2′-naphthalene]-2,5-dione (3); (b) monomers: 5,5-dimethyl-3-(4-vinylbenzyl)imidazolidine-2,4-dione (4), 1-(4-vinylbenzyl)-1′,3′-dihydrospiro[imidazolidine-4,2′-indene]-2,5-dione (5), 1-(4-vinylbenzyl)-3′,4′-dihydro-1′H-spiro[imidazolidine-4,2′-naphthalene]-2,5-dione (6), (two of them are unknown: 5 and 6); (c) macromolecular compounds: poly(chloromethyl-p-styrene) (7), used as reference, and three polymers (two of them are novel) obtained by substitution of hydantoins 1–3 to poly(methyl-p-styrene) (8–10). Their thermal properties have been studied by thermogravimetry. It was found that the chemical structure, tautomerization, and intermolecular interaction influence the thermal stability of substrates. The presence of phenyl rings causes the increase of resistance of studied hydantoins. The obtained polymers are characterized by significantly improved thermal stability comparing to poly (chloromethyl-p-styrene). The mechanism of thermal degradation of investigated polymers and explanation of their thermal resistance has been proposed. The relatively high temperatures of glass transition of polymers have been determined by DSC.

Simple and efficient synthesis with theoretical calculations of novel N-halamine monomers

Hydantoins represent a group of compounds which over the past few years has attracted great attention because of their diverse biological activities. The synthetic methods for 5,5-dimetyhyl hydantoin (well-known biocidal material) available in literature are particularly difficult, and the yield of the synthesis after purification does not exceed 40%. On the other hand, styrene-type monomers containing spirohydantoin moieties were successfully synthesized by N-alkylation reaction. A simple and efficient preparation of N-chlorinated (N-halamine) monomers is presented, and the experimental data are supported by DFT calculations.

The chitosan – Porphyrazine hybrid materials and their photochemical properties

Three magnesium sulfanyl porphyrazines differing in the size of peripheral substituents (3,5-dimethoxybenzylsulfanyl, (3,5-dimethoxybenzyloxy)benzylsulfanyl, 3,5-bis[(3,5-bis[(3,5-dimethoxybenzyloxy)benzyloxy]benzylsulfanyl) were exposed to visible and ultraviolet radiation (UV A + B + C) in order to determine their photochemical properties. The course of photochemical reactions in dimethylformamide solutions and the ability of the systems to generate singlet oxygen were studied by UV-Vis spectroscopy, which additionally gave information on aggregation processes. The porphyrazines were found to be stable upon visible light irradiation conditions, but when exposed to high energy UV radiation, the efficient photodegradation of these macrocycles was observed. Therefore, these three magnesium sulfanyl porphyrazines were incorporated into chitosan matrix. The obtained thin films of chitosan doped with porphyrazines were subjected to polychromatic UV-radiation and studied by spectroscopic methods (UV-Vis, FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Application of chitosan as a polymer matrix for porphyrazines was found to be successful method that effectively stopped the unwelcome degradation of macrocycles, thus worth considering for their photoprotection. In addition, the surface properties of the hybrid material were determined by contact angle measurements and calculation of surface free energy. Intermolecular interactions between these novel porphyrazines and chitosan were detected. The mechanism of photochemical reactions occurring in studied systems has been discussed.