Mechanochemistry as a versatile and scalable tool for nanomaterials synthesis: Recent achievements in Košice,Slovakia

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Arsenic speciation patterns in freshwater fish

Muscle of 16 freshwater fish (9 different species belonging to 4 different families) was analysed for arsenic species using HPLC separation (anion and cation exchange) followed by on-line UV-decomposition, hydride generation and AFS detection. The main arsenic compounds found in the extracts were arsenobetaine (AsB), which accounted for 92–100% of extractable arsenic in species of salmonids (Salmo marmoratus, Oncorhynchus mykiss, Salmo trutta m. fario), and dimethylarsinic acid (DMAA), which accounted for 75% of extractable arsenic in burbot (Lota lota). AsB was also found in lower concentrations in almost all other fish species analysed (Silurus glanis, L. lota, Barbus barbus, Rutilus pigus virgo, Chondrostoma nasus). Arsenite (As(III)) and trimethylarsine oxide (TMAO) were detected in low concentrations in some representatives of Cyprinidae only (R. pigus virgo, C. nasus). Except in salmonids, an unknown cationic compound was present in most of the samples in relatively low concentrations. Cluster analysis of the generated data seems to indicate that there is a correlation between fish family and the arsenic speciation pattern. This is especially clear for the salmonids which show a completely separate cluster and thus a very distinct arsenic speciation pattern.     

A Rapid Method for the Determination of Organochlorine, Pyrethroid Pesticides and Polychlorobiphenyls in Fatty Foods Using GC with Electron Capture Detection

A new, single-step extraction and purification method was developed for the separation of 26 organochlorine pesticides (OCPs), three pyrethroid pesticides (PPs) and six polychlorinated biphenyls (PCBs) from fatty foods of either animal or vegetable origin. The method includes homogenisation of extracted fat and diatomaceous earth. Separation was achieved using a mini Pasteur pipette where a matrix solid-phase dispersion extraction was carried out with only 5 mL of dimethyl sulphoxide as an eluting solvent. A Pasteur pipette was joined to a prepacked slurry filled Florisil column, water deactivated to 15% where a liquid–liquid extraction and adsorption chromatography successively took place. The elution of OCPs, PPs and PCBs was performed with n-hexane/diethyl ether. Recoveries for PCBs were from 81 to 86% and for OCPs 68 to 94%, except for β-HCH, which gave lower, more variable recoveries. Excellent recoveries were obtained for pyrethroid pesticides, mostly more than 80%. The method was applied to 509 fatty samples for monitoring of these compounds. GC, with two columns connected to two electron capture detectors (ECD), was used.     

Unusual nonreducing sugar GlcNAcβ(1↔1)Manβ formation by β-N-acetylhexosaminidase from Aspergillus oryzae

β-N-Acetylhexosaminidase from Aspergillus oryzae catalyzes the transfer of N-acetylglucosamine moiety from pNP-β-GlcNAc to mannose giving major product GlcNAcβ(1↔1)Manβ (1a), and GlcNAcβ(1→3)Man/β (2a) and GlcNAcβ(1→6)Man/β (3a) as two minor products.     

Study of pepsin phosphorylation using immobilized metal affinity chromatography

The interactions of pepsin with immobilized trivalent metal ions and the participation of the enzyme phosphate group in this process were investigated using high performance immobilized metal affinity chromatography. Two different sorbents were used: the newly prepared one, consisting of Ga(3+ )chelate of (6-amino-1-hydroxyhexane-1,1-diyl) bis(phosphonic acid) covalently bound to a methacrylate support (BP-Ga(3+)), and the commercial one, containing immobilized Fe(3+ )ions (POROS MC20-Fe(3+)). The comparison of the behavior of porcine pepsin A and its partially dephosphorylated form on both sorbents showed that both forms of pepsin were adsorbed under the same conditions. To eliminate the participation of free carboxyl groups in pepsin adsorption, both enzyme forms were modified by amidation or esterification. Native enzyme and its partially dephosphorylated form both with modified carboxyl groups differed in their interaction with immobilized Ga(3+ )and Fe(3+). Phosphorylated pepsin molecules with esterified carboxyl groups were adsorbed on both sorbents while nonphosphorylated ones with esterified carboxyl groups were not adsorbed.     

Poly(ethylene glycol) (PEG) enhances dynamic surface activity of a bovine lipid extract surfactant (BLES)

Shortage or malfunction of pulmonary surfactant in alveolar space leads to a critical condition termed respiratory distress syndrome (RDS). Surfactant replacement therapy, the major method to treat RDS, is an expensive treatment. In this paper, the effect of poly(ethylene glycol) (PEG) to improve dynamic surface activity of a bovine lipid extract surfactant (BLES) was studied by axisymmetric drop shape analysis (ADSA) and a captive bubble method. The activity of BLES+PEG mixtures was compared to that of a natural surfactant containing surfactant proteins A and D. When PEG was added into BLES mixtures, the surface tension hysteresis of BLES films was minimized when the films were compressed by more than 50%. PEG also helps to quickly restore surfactant films after film collapse. Thus, as far as surface tension effects go, the findings suggest that PEG might be used as a substitute for surfactant-associated protein SP-A in therapeutic surfactant products, and might also be used to reduce the amount of BLES required in clinical applications.     

5βH,6αH,7αH,10αCH3-eudesman-6,12-olides: A novel stereochemical group of natural sesquiterpene lactones. Stereostructure of isosilerolide

A new stereochemical group of eudesmanolides - 5βH,6αH,7αH,10αCH₃-eudesman-6,12-olides - was identified mainly on the basis of proton NMR spectroscopy and checked by X-ray analysis     

Internalization of Ineffective Platinum Complex in Nanocapsules Renders It Cytotoxic

Anticancer therapy by platinum complexes, based on nanocarrier‐based delivery, may offer a new approach to improve the efficacy and tolerability of the platinum family of anticancer drugs. The original rules for the design of new anticancer platinum drugs were affected by the fact that, although cisplatin (cis‐[PtCl₂(NH₃)₂) was an anticancer drug, its isomer transplatin was not cytotoxic. For the first time, it is demonstrated that simple encapsulation of an inactive platinum compound in phospholipid bilayers transforms it into an efficient cytotoxic agent. Notably, the encapsulation of transplatin makes it possible to overcome the resistance mechanisms operating in cancer cells treated with cisplatin and prevents inactivation of transplatin in the extracellular environment. It is also shown that transplatin delivered to the cells in nanocapsules, in contrast to free (nonencapsulated) complex, forms cytotoxic cross‐links on DNA.