Jindrich Kynicky

Complexes of Silver(I) Ions and Silver Phosphate Nanoparticles with Hyaluronic Acid and/or Chitosan as Promising Antimicrobial Agents for Vascular Grafts

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes.

Simultaneous Automatic Electrochemical Detection of Zinc, Cadmium, Copper and Lead Ions in Environmental Samples Using a Thin-Film Mercury Electrode and an Artificial Neural Network

In this study a device for automatic electrochemical analysis was designed. A three electrodes detection system was attached to a positioning device, which enabled us to move the electrode system from one well to another of a microtitre plate. Disposable carbon tip electrodes were used for Cd(II), Cu(II) and Pb(II) ion quantification, while Zn(II) did not give signal in this electrode configuration. In order to detect all mentioned heavy metals simultaneously, thin-film mercury electrodes (TFME) were fabricated by electrodeposition of mercury on the surface of carbon tips. In comparison with bare electrodes the TMFEs had lower detection limits and better sensitivity. In addition to pure aqueous heavy metal solutions, the assay was also performed on mineralized rock samples, artificial blood plasma samples and samples of chicken embryo organs treated with cadmium. An artificial neural network was created to evaluate the concentrations of the mentioned heavy metals correctly in mixture samples and an excellent fit was observed (R2 = 0.9933).

Microfluidic Chip Coupled with Modified Paramagnetic Particles for Sarcosine Isolation in Urine

Carcinoma of prostate (CaP) is the second most frequent malignant tumor occurring in men in Europe. Currently there is discussion on a wide range of potential CaP markers. One of them—nonprotein amino acid sarcosine, also known as N‐methylglycine was chosen as a challenge for the development of microfluidic system with isolation by modified paramagnetic microparticles. Therefore, the aim of this study was to design a low‐cost, simple, and rapid microfluidic system based on sarcosine isolation with modified paramagnetic microparticles and subsequent analysis on the ion exchange LC. We modified Dowex microparticles with Fe2O3 nanoparticles. Our paramagnetic microparticles were able to establish the binding with sarcosine. Moreover, we designed microfluidic device for sarcosine determination. Analysis of samples was carried out with LOD of 1 μM of a sarcosine that is sufficient because it is similar to concentrations of a sarcosine observed in the CaP patients.

Bio-sensing of cadmium(II) ions using Staphylococcus aureus.

Cadmium, as a hazardous pollutant commonly present in the living environment, represents an important risk to human health due to its undesirable effects (oxidative stress, changes in activities of many enzymes, interactions with biomolecules including DNA and RNA) and consequent potential risk, making its detection very important. New and unique technological and biotechnological approaches for solving this problems are intensely sought. In this study, we used the commonly occurring potential pathogenic microorganism Staphylococcus aureus for the determination of markers which could be used for sensing of cadmium(II) ions. We were focused on monitoring the effects of different cadmium(II) ion concentrations (0, 1.25, 2.5, 5, 10, 15, 25 and 50 μg mL−1) on the growth and energetic metabolism of Staphylococcus aureus. Highly significant changes have been detected in the metabolism of thiol compounds—specifically the protein metallothionein (0.79–26.82 mmol/mg of protein), the enzyme glutathione S-transferase (190–5,827 μmol/min/mg of protein), and sulfhydryl groups (9.6–274.3 μmol cysteine/mg of protein). The ratio of reduced and oxidized glutathione indicated marked oxidative stress. In addition, dramatic changes in urease activity, which is connected with resistance of bacteria, were determined. Further, the effects of cadmium(II) ions on the metabolic pathways of arginine, β-glucosidase, phosphatase, N-acetyl β-d-glucosamine, sucrose, trehalose, mannitol, maltose, lactose, fructose and total proteins were demonstrated. A metabolomic profile of Staphylococcus aureus under cadmium(II) ion treatment conditions was completed seeking data about the possibility of cadmium(II) ion accumulation in cells. The results demonstrate potential in the application of microorganisms as modern biosensor systems based on biological components.

Investigation of interaction between magnetic silica particles and lambda phage DNA fragment

Nucleic acids belong to the most important molecules and therefore the understanding of their properties, function and behavior is crucial. Even though a range of analytical and biochemical methods have been developed for this purpose, one common step is essential for all of them - isolation of the nucleic acid from the from complex sample matrix. The use of magnetic particles for the separation of nucleic acids has many advantages over other isolation methods. In this study, an isolation procedure for extraction of DNA was optimized. Each step of the isolation process including washing, immobilization and elution was optimized and therefore the efficiency was increased from 1.7% to 28.7% and the total time was shortened from 75 to 30min comparing to the previously described method. Quantification of the particular parameter influence was performed by square-wave voltammetry using hanging drop mercury electrode. Further, we compared the optimized method with standard chloroform extraction and applied on isolation of DNA from Staphylococcus aureus and Escherichia coli.

A 3D microfluidic chip for electrochemical detection of hydrolysed nucleic bases by a modified glassy carbon electrode.

Modification of carbon materials, especially graphene-based materials, has wide applications in electrochemical detection such as electrochemical lab-on-chip devices. A glassy carbon electrode (GCE) modified with chemically alternated graphene oxide was used as a working electrode (glassy carbon modified by graphene oxide with sulphur containing compounds and Nafion) for detection of nucleobases in hydrolysed samples (HCl pH = 2.9, 100 °C, 1 h, neutralization by NaOH). It was found out that modification, especially with trithiocyanuric acid, increased the sensitivity of detection in comparison with pure GCE. All processes were finally implemented in a microfluidic chip formed with a 3D printer by fused deposition modelling technology. As a material for chip fabrication, acrylonitrile butadiene styrene was chosen because of its mechanical and chemical stability. The chip contained the one chamber for the hydrolysis of the nucleic acid and another for the electrochemical detection by the modified GCE. This chamber was fabricated to allow for replacement of the GCE.

Comparative study on toxicity of extracellularly biosynthesized and laboratory synthesized CdTe quantum dots

Nanobiosynthesis belongs to the most recent methods for synthesis of nanoparticles. This type of synthesis provides many advantages including the uniformity in particle shape and size. The biosynthesis has also a significant advantage regarding chemical properties of the obtained particles. In this study, we characterized the basic properties and composition of quantum dots (QDs), obtained by the extracellular biosynthesis by Escherichia coli. Furthermore, the toxicity of the biosynthesized QDs was compared to QDs prepared by microwave synthesis. The obtained results revealed the presence of cyan CdTe QDs after removal of substantial amounts of organic compounds, which stabilized the nanoparticle surface. QDs toxicity was evaluated using three cell lines Human Foreskin Fibroblast (HFF), Human Prostate Cancer cells (PC-3) and Breast Cancer cells (MCF-7) and the MTT assay. The test revealed differences in the toxicity between variants of QDs, varying about 10% in the HFF and 30% in the MCF-7 cell lines. The toxicity of the biosynthesized QDs to the PC-3 cell lines was about 35% lower in comparison with the QDs prepared by microwave synthesis.

Behaviour of Zinc Complexes and Zinc Sulphide Nanoparticles Revealed by Using Screen Printed Electrodes and Spectrometry

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl2, Zn(his)Cl2) 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)Cl2, Zn(his)Cl2) 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.

Rare earth element enrichment in Palaeoproterozoic Fengzhen carbonatite from the North China block

ABSTRACT Carbonatites are characterized by the highest concentration of rare earth elements (REEs) of any igneous rock and are therefore good targets for REE exploration. Supergene, hydrothermal, and magmatic REE deposits associated with carbonatites have been widely studied. REE enrichment related to fluorapatite metasomatism in Fengzhen carbonatites in the North China block is reported in this study. REE minerals (monazite, britholite, and Ca-REE-fluorocarbonates) associated with barite and quartz formed as inclusions within the fluorapatite and externally on its surface. Monazite, allanite, barite, and quartz occur as rim grains on the edges of the fluorapatite. Zoned fluorapatite was observed and showed varying chemical composition. Based on back-scattered electron imaging, the dark domains with mineral inclusions contain lower Si (0.3–0.6 wt.% SiO2) and light REE (LREE) [0.36–1.54 wt.% (Y+LREE)2O3] contents than inclusion-poor areas [0.7–1 wt.% SiO2; 2.16–4.51 wt.% (Y + LREE)2O3]. This indicates a dissolution–re-precipitation texture. Different types of monazites were distinguished by their chemical compositions. Monazite inclusions have lower La2O3contents (~13 wt.%) and La/Ndcn (~3) ratios than those (18–26 wt.% and 10–14 for La2O3 and La/Ndcn, respectively) growing externally on the fluorapatite. REE enrichment in the metasomatic fluorapatites is related to different stages of carbonatitic liquids. The early carbonatite-exsolved fluids metasomatized the fluorapatites to form REE mineral inclusions. The late carbonatitic fluids from carbonatite magmas that underwent strong fractional crystallization were enriched in REEs, Al, and Fe and metasomatized the fluorapatites to produce allanite and monazite rim grains.

Rapid superparamagnetic‐beads‐based automated immunoseparation of Zn‐proteins from Staphylococcus aureus with nanogram yield

Pathogenic bacteria have become a serious socio‐economic concern. Immunomagnetic separation‐based methods create new possibilities for rapidly recognizing many of these pathogens. The aim of this study was to use superparamagnetic particles‐based fully automated instrumentation to isolate pathogen Staphylococcus aureus and its Zn(II) containing proteins (Zn‐proteins). The isolated bacteria were immediately purified and disintegrated prior to immunoextraction of Zn‐proteins by superparamagnetic beads modified with chicken anti‐Zn(II) antibody. S. aureus culture was treated with ZnCl2. Optimal pathogen isolation and subsequent disintegration assay steps were carried out with minimal handling. (i) Optimization of bacteria capturing: Superparamagnetic microparticles composed of human IgG were used as the binding surface for acquiring live S. aureus. The effect of antibodies concentration, ionic strength, and incubation time was concurrently investigated. (ii) Optimization of zinc proteins isolation: pure and intact bacteria isolated by the optimized method were sonicated. The extracts obtained were subsequently analyzed using superparamagnetic particles modified with chicken antibody against zinc(II) ions. (iii) Moreover, various types of bacterial zinc(II) proteins precipitations from particle–surface interactions were tested and associated protein profiles were identified using SDS‐PAGE. Use of a robotic pipetting system sped up sample preparation to less than 4 h. Cell lysis and Zn‐protein extractions were obtained from a minimum of 100 cells with sufficient yield for SDS‐PAGE (tens ng of proteins). Zn(II) content and cell count in the extracts increased exponentially. Furthermore, Zn(II) and proteins balances were determined in cell lysate, extract, and retentate.