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.

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.

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 (K_m 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 K_m 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.

The extraction efficiency of the Albanian “Moro” cultivar orange peel extract using supercritical CO2 (scCO2) extraction and ultrasonic extraction (USE) is studied. ScCO₂ extractions were carried out at 200 atm, 40°C, flow rate of 1.6 ml/min, particle size of 0.5-1 mm combined by two extraction modes. The USE were studied within a time period of 5 - 60 min applying a bath power of 10 W. CH2Cl₂ served as collecting /extracting medium in both studied methods. An essential oil yield of 0.21 % for 60 min sonication time was recorded for USE compared to 0.23 % for scCO₂ extraction when using a 15 min static extraction mode followed by a consecutive dynamic mode. Within the first 22 min, 83 % and 73 % of extract were obtained for scCO₂ extraction and USE respectively. Limonene as the major extract component varied from 89-91 % followed by β-myrcene, decanal, α-pinene, linalool and valencene.

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 – 60 V / 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, β- myrcene, 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.

Two benzimidazole derivatives, i.e. 2-(2-aminophenyl)-1H-benzimidazole (APhBI) and 2-(2-hydroxophenyl)-1H-benzimidazole (HPhBI) were found to successfully mitigate the corrosion of S235 steel in 1 M HCl solution, at 298–318 K.