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Increasing urbanization and industrialization lead to the release of metals into the biosphere, which has become a serious issue for public health. In this paper, the direct electrochemical reduction of zinc ions is studied using electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). The graphene oxide (GO) was fabricated using modified Hummers method and was electrochemically reduced on the surface of GCE by performing cyclic voltammograms from 0 to −1.5 V. The modification was optimized and properties of electrodes were determined using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The determination of Zn(II) was performed using differential pulse voltammetry technique, platinum wire as a counter electrode, and Ag/AgCl/3 M KCl reference electrode. Compared to the bare GCE the modified GCE/ERGO shows three times better electrocatalytic activity towards zinc ions, with an increase of reduction current along with a negative shift of reduction potential. Using GCE/ERGO detection limit 5 ng·mL−1 was obtained.

In this study, enhancement of the electrochemical signals of etoposide (ETO) measured by differential pulse voltammetry (DPV) by modifying a glassy carbon electrode (GCE) with carbon quantum dots (CQDs) is demonstrated. In comparison with a bare GCE, the modified GCE exhibited a higher sensitivity towards electrochemical detection of ETO. The lowest limit of detection was observed to be 5 nM ETO. Furthermore, scanning electron microscopy (SEM), fluorescence microscopy (FM), and electrochemical impedance spectroscopy (EIS) were employed for the further study of the working electrode surface after the modification with CQDs. Finally, the GCE modified with CQDs under optimized conditions was used to analyse real samples of ETO in the prostate cancer cell line PC3. After different incubation times (1, 3, 6, 9, 12, 18 and 24 h), these samples were then prepared prior to electrochemical detection by the GCE modified with CQDs. High performance liquid chromatography with an electrochemical detection method was employed to verify the results from the GCE modified with CQDs.

The compounds In5Ch5X (Ch = S, Se; X = Cl, Br) represent new mixed valence solids with indium occurring simultaneously in three different oxidation states: In+, In3+ and In2+ where the latter appears as covalently bonded dumbbells (In2)4+. Although the ionic formulation (In5Ch5X = In+ 2In3+ (In2)4+ 5Ch2— X—) is the same for all compounds, they crystallise in two structure types (In5Ch5Cl‐type: monoclinic, P21/m, Z = 2; In5Ch5Br‐type: orthorhombic, Pmn21, Z = 2). Ignoring the distribution of the halogen atoms, the anionic partial structure is very similar in both structure types. The main difference is an exchange of (In+) by (In2)4+ and vice versa on selected positions. This is possible due to the nearly identical coordination of both ions (tri‐capped trigonal prisms). HRTEM investigations show remarkable differences in the real structures of In5Ch5Cl and In5Ch5Br. In contrast to the perfectly ordered crystals of the bromides, the chlorides exhibit a variety of nanoscaled crystal defects, i.e. twinning, polylamellar intergrowth of polymorphs and lamellar intergrowth of structurally related compounds as demonstrated in In5S5Cl/In6S7. The occurrence of these defects is discussed using an appropriate structure model.

In this work, we focused on the differences between bacterial cultures of E. coli obtained from swabs of infectious wounds of patients compared to laboratory E. coli. In addition, blocking of the protein responsible for the synthesis of glutathione (γ-glutamylcysteine synthase—GCL) using 10 mM buthionine sulfoximine was investigated. Each E. coli showed significant differences in resistance to antibiotics. According to the determined resistance, E. coli were divided into experimental groups based on a statistical evaluation of their properties as more resistant and more sensitive. These groups were also used for finding the differences in a dependence of the glutathione pathway on resistance to antibiotics. More sensitive E. coli showed the same kinetics of glutathione synthesis while blocking GCL (Km 0.1 µM), as compared to non-blocking. In addition, the most frequent mutations in genes of glutathione synthetase, glutathione peroxidase and glutathione reductase were observed in this group compared to laboratory E.coli. The group of “more resistant” E. coli exhibited differences in Km between 0.3 and 0.8 µM. The number of mutations compared to the laboratory E. coli was substantially lower compared to the other group.

In the course of the actual investigation, we focused our research on the extraction of the orange peel extract of "Moro" cultivars grown in Albania using ultrasonic and soxhlet extractions techniques. The ultrasonic extractions performed in "SONOREX TK 52" 40 -60V / 100 W, using methylene chloride and applying sonication times up to two hours, revealed the presence of more than 20 components among which limonene, as the major extract component represents more than 91 % of the extract, followed by linalool, βmyrcene, decanal, α-pinene and valencene. More than 90 % of the extraction yield was obtained within 30 min. of extraction. The ratio between extracted components changed significantly in this method while using various solvents. The highest extraction yield was recovered when using methanol (0.548 %) followed by methylene chloride (0.414 %), hexane + acetone (0.272 %), hexane (0.141 %). In parallel to this method, the soxhlet extractions performed in a 20 ml soxhlet extractor for 6 hours (56 cycles) using the same solvents showed surprisingly lower extraction yields and different component ratios for all of them. In hexane + acetone the percentage of limonene was 85 %, meanwhile, in methanol this percentage decreased until 43 %. In this comparison the advantage of ultrasounds in desorption, diffusion and dissolution of components from the sample matrices is obvious.

Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of −0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

Inorganic nanoparticles might have played a vital role in the transition from inorganic chemistry to self-sustaining living systems. Such transition may have been triggered or controlled by processes requiring not only versatile catalysts but also suitable reaction surfaces. Here, experimental results showing that multicolor quantum dots might have been able to participate as catalysts in several specific and nonspecific reactions, relevant to the prebiotic chemistry are demonstrated. A very fast and easy UV-induced formation of ZnCd quantum dots (QDs) with a quantum yield of up to 47% was shown to occur 5 min after UV exposure of the solution containing Zn(II) and Cd(II) in the presence of a thiol capping agent. In addition to QDs formation, xanthine activity was observed in the solution. The role of solar radiation to induce ZnCd QDs formation was replicated during a stratospheric balloon flight.