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The removal of selenium from superficial and waste water is a worldwide problem. The maximum limit according to the World Health Organization (WHO) for the selenium in the water is set at a concentration of 10 &mu, g/L. Carbon based adsorbents have attracted much attention and recently demonstrated promising performance in removal of selenium. In this work, several materials (iron oxide based microparticles and graphene oxides materials) and their composites were prepared to remove Se(IV) from water. The graphene oxides were prepared according to the simplified Hummer&rsquo, s method. In addition, the effect of pH, contact time and initial Se(IV) concentration was tested. An electrochemical method such as the differential pulse cathodic stripping voltammetry was used to determine the residual selenium concentration. From the experimental data, Langmuir adsorption model was used to calculate the maximum adsorption capacity. Graphene oxide particles modified by iron oxide based microparticles was the most promising material for the removal of Se(IV) from its aqueous solution at pH 2.0. Its adsorption efficiency reached more than 90% for a solution with given Se(IV) concentration, meanwhile its maximal recorded adsorption capacity was 18.69 mg/g.

a b s t r a c t Arsenic compounds belong to the most controversial agents concerning human health. Arsenic (As) is considered as a top environmental element influencing human health due to its adverse effects includ- ing cancer, diabetes, cardiovascular disease, and reproductive or developmental problems. Despite the proven mutagenic, teratogenic and carcinogenic effects, the arsenic compounds are used for centuries to treat infectious diseases. In our work, we focused on studying of interactions of As(III) and/or As(V) with DNA. Interactions between arsenic ions and DNA were monitored by UV/vis spectrophotometry by measuring absorption and fluorescence spectra, atomic absorption spectrometry, electrochemical measurements (square wave voltammetry) and agarose gel electrophoresis. Using these methods, we observed a stable structure of DNA with As(III) within the concentration range 0.4-6.25 g mL −1 . Higher As(III) concentration caused degradation of DNA. However, similar effects were not observed for As(V).

Liposome-based drug delivery systems hold great potential for cancer therapy. The aim of this study was to design a nanodevice for targeted anchoring of liposomes (with and without cholesterol) with encapsulated anticancer drugs and antisense N-myc gene oligonucleotide attached to its surface. To meet this main aim, liposomes with encapsulated doxorubicin, ellipticine and etoposide were prepared. They were further characterized by measuring their fluorescence intensity, whereas the encapsulation efficiency was estimated to be 16%. The hybridization process of individual oligonucleotides forming the nanoconstruct was investigated spectrophotometrically and electrochemically. The concentrations of ellipticine, doxorubicin and etoposide attached to the nanoconstruct in gold nanoparticle-modified liposomes were found to be 14, 5 and 2 µg•mL(-1), respectively. The study succeeded in demonstrating that liposomes are suitable for the transport of anticancer drugs and the antisense oligonucleotide, which can block the expression of the N-myc gene. Systémy transportu léčiv pomocí liposomů udržují velký potenciál pro léčbu rakoviny. Cílem této studie bylo navrhnout nanozařízení pro cílené ukotvení liposomů (s a bez cholesterolu) s enkapsulovanými protinádorovými léky a k povrchu připojeným antisense oligonukleotidem pro gen n-myc. K dosažení tohoto hlavního cíle byly připraveny liposomy s enkapsulovaným doxorubicinem, ellipticinem a etoposidem. Byly charakterizovány měřením intenzity fluorescence, zatímco účinnost enkapsulace byla odhadována na 16 %. Proces hybridizace jednotlivých oligonukleotidů tvořících nanokonstrukt byl sledován spektrofotometricky a elektrochemicky. Koncentrace ellipticinu, doxorubicinu a etoposidu připojených k nanokonstruktu v liposomech modifikovaných zlatými nanočásticemi byly 14, 5 a 2 µg•ml(-1). Autorům studie se podařilo prokázat, že liposomy jsou vhodné pro transport protinádorových léků a antisense oligonukleotidu, který může blokovat expresi n-myc genu.

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl-2, Zn(his)Cl-2) and ZnS quantum dots (QDs) using printed electrodes. This method was chosen due to the simple (easy to use) instrumentation and variable setting of flows. Reduction signals of zinc under the strictly defined and controlled conditions (pH, temperature, flow rate, accumulation time and applied potential) were studied. We showed that the increasing concentration of the complexes (Zn(phen)(his)Cl-2, Zn(his)Cl-2) led to a decrease in the electrochemical signal and a significant shift of the potential to more positive values. The most likely explanation of this result is that zinc is strongly bound in the complex and its distribution on the electrode is very limited. Changing the pH from 3.5 to 5.5 resulted in a significant intensification of the Zn(II) reduction signal. The complexes were also characterized by UV/VIS spectrophotometry, chromatography, and ESI-QTOF mass spectrometry. V této studii jsme se zaměřili na mikrofluidní elektrochemickou analýzu komplexů zinku (Zn (fenyl) (jeho) Cl-2, Zn (jeho) Cl-2) a ZnS kvantové tečky (QDS) za použití tištěných elektrod. Tato metoda byla zvolena z důvodu jednoduchému (snadné použití přístrojového vybavení) a variabilnímu nastavení toků. Byly studovány signály Redukční zinku v rámci přísně definovaných a kontrolovaných podmínek (pH, teplota, průtok, doba akumulace a aplikované potenciál). Ukázali jsme, že zvyšující se koncentrace komplexů (Zn (phen) (jeho) Cl-2, Zn (jeho) Cl-2) vede ke snížení elektrochemického signálu a významný posun potenciálu na více pozitivních hodnot. Nejpravděpodobnějším vysvětlením tohoto výsledku je, že zinek je silně vázána v komplexu a jeho rozložení na elektrodě je velmi omezený. Změna pH 3,5-5,5 vedlo k významnému zesílení Zn (II) signálu snížení. Komplexy byly také charakterizovány pomocí UV spektrofotometrie / VIS, chromatografie a ESI-QTOF hmotnostní spektrometrií. (Přeloženo strojově)