Anna Yu. Godymchuk

Considerable Variation of Antibacterial Activity of Cu Nanoparticles Suspensions Depending on the Storage Time, Dispersive Medium, and Particle Sizes

Suspensions of Cu nanoparticles are promising for creating the new class of alternative antimicrobial products. In this study we examined copper nanoparticles of various sizes obtained by the method of wire electric explosion: nanopowder average size 50 nm (Cu 50) and 100 nm (Cu 100). The paper presents the complex study of the influence of physicochemical properties such as particle size and concentration of the freshly prepared and 24-hour suspensions of Cu nanoparticles in distilled water and physiological solution upon their toxicity to bacteria E. coli M-17. Ionic solution of Cu2+ and sodium dichloroisocyanurate was used for comparison study. It has been shown that decrease in the nanoparticle size leads to changes in the correlation between toxicity and concentration as toxicity peaks are observed at low concentrations (0.0001⋯0.01 mg/L). It has been observed that antibacterial properties of Cu 50 nanoparticle suspensions are ceased after 24-hour storage, while for Cu 100 suspensions no correlation between antibacterial properties and storage time has been noted. Cu 100 nanoparticle suspensions at 10 mg/L concentration display higher toxicity at substituting physiological solution for water than Cu 50 suspensions. Dependence of the toxicity on the mean particle aggregates size in suspension was not revealed.

Morphometric Parameters and Biochemical Status of Oilseed Rape Exposed to Fine-dispersed Metallurgical Sludge, PHMB-stabilized Silver Nanoparticles and Multi-wall Carbon Nanotubes

Thepaper Presents Biological Properties of Threefine-Dispersed Materials, Namely Metallurgical Sludge, Colloidal Silver Andmulti-Wall Carbon Nanotubes (MWCNT) Exposing Oilseed Rape Plants. the Stimulationof Plant’s Growth by Silver Nanoparticles and the Intensification of Plantpigments Synthesis by MWCNT have been Experimentally Demonstrated. A Small Decreasein Energy and Germination Capacity were Noticed Whereby Colloidal Silver Hadthe Lowest Suppressive Effect, MWCN Tubes had the Highest Effect, and Sludge Wasfound in between Two above-Mentioned Materials. According to the Research, the Usageof Sludge is the most Effective at the Concentration of 10 and 100 g/l,colloidal Silver – 10 g/l and 300 g/l, MWCNT – 0,001 g/l and 1 g/l.

Difficulties and flaws in performing accurate determinations of zeta potentials of metal nanoparticles in complex solutions—Four case studies

The zeta potential (ZP) is a parameter commonly used to characterize metal nanoparticles (NPs) in solution. Such determinations are for example performed in nanotoxicology since the ZP influences e.g. the interaction between cells and different biomolecules. Four case studies on different metal NPs (Cu and Zn NPs, and citrate capped Ag NPs) are presented in this study in order to provide guidance on how to accurately interpret and report ZP data. Solutions of high ionic strength (150 mM NaCl) induce a higher extent of particle agglomeration (elucidated with Ag NPs) when compared with conditions in 10 mM NaCl, which further complicates the prediction of the ZP due to e.g. sedimentation and broadening of the zeta potential distribution. The particle size is seldom included specifically in the standard ways of determining ZP (Hückel and Smoluchowski approximations). However corrections are possible when considering approximations of the Henry function. This was seen to improve the analysis of NPs, since there are cases when both the Hückel and the Smulochowski approximations are invalid. In biomolecule-containing cell media (BEGM), the signal from e.g. proteins may interfere with the measured ZP of the NPs. The intensity distribution of the ZP of both the blank solution and the solution containing NPs should hence be presented in addition to the mean value. Due to an increased ionic strength for dissolving of metal NPs (exemplified by Zn NPs), the released metal ions must be considered when interpreting the zeta potential measurements. In this work the effect was however negligible, as the particle size was several hundred nm, conditions that made the Smoluchowski approximation valid despite an increased ionic strength. However, at low ionic strengths (mM range) and small-sized NPs (tens of nm), the effect of released metal ions can influence the choice of model for determining the zeta potential. Sonication of particle dispersions influences not only the extent of metal release but also the outermost surface oxide composition, which often results in an increased ZP. Surface compositional changes were illustrated for sonicated and non-sonicated Cu NPs. In all, it can be concluded that accurate measurements and interpretations are possible in most cases by collecting and reporting complementary data on characteristics such as particle size, ZP distributions, blank sample information, and particle oxide composition.

Antimicrobial Activity of Differently Concentrated Nanoparticle Dispersions

Preparation of nontoxic antimicrobial solutions is a priority in the development of new antibiotics. The in vitro effect of the chemical composition of the dispersed phase and dissolved solids in the dispersion medium on the antimicrobial properties of aqueous colloidal solutions of nanoparticles of a number of metals and metal oxides against microorganisms of different species - bacterial dental plaque, Bacillus cereus, and spores of vaccine strain Bacillus anthracis STI - 1 were studied in this work.

Exposure of nano- and ultrafine Ni particles to synthetic biological solutions: predicting fate-related dissolution and accumulation

Abstract The growing production and use of nickel (Ni) nanopowders with low biopersistence makes dissolution and accumulation degree in a body an important parameters needed for the risk assessment of nanoparticles. We propose an experimental approach for rapid determination of the dissolution degree of nanoscale (77 nm) and ultrafine (275 nm) Ni particles in synthetic biological solutions. It has been shown that after 2 h of exposure to simulating saliva and lysosomal liquid the dissolution degree of nanoparticles can reach 30 and 60 wt.%, respectively. With decreasing of the particle’s size, they are characterized by increased solubility in saliva and the pulmonary tract; and the particles completely dissolve in 24 h. There was an attempt to predict the potential extent of accumulation of nickel compounds in the human body with particles entering the body by saliva or with breathing: with 3.8 times size decrease the probability of nickel accumulation in a body can rise in 3.5 times.

High Physicochemical Persistence of Aluminum Nanoparticles in Synthetic Body Fluids

When nanoparticles get into a living body, they interact with body fluids. This study shows high physicochemical persistence of electroexplosive aluminum nanoparticles in physiological solutions simulating body fluids: Artificial Sweat (ASw), Simulated Saliva (SS), Simulated Gastric Fluid (SGF), and Artificial Alveolar Fluid (AAF). It has been demonstrated that after 14 days of exposure in ASw SS SGF AAF solutions, the average size of initial 90 nm nanoparticles became 90 100 230 90 nm, and the average size of initial 5 μm agglomerates became 1.6 0.9 1.0 3.0 μm, respectively. According to s SEM data, the exposed particles retained their spherical shape. With the help of the X-ray phase analysis it was shown that the oxide/hydroxide phase content in nanoparticles did not increase. It has been concluded that highly-reactive aluminum nanoparticles are capable to retain their phase composition, dispersion, and morphology in synthetic body fluids.

Dissolution of zinc nanoparticles in pulmonary fluid

Inhaled from the ambient air nanoparticles may reach innermost areas of respiratory tract, alveolar sacs, particularly. In this work the dissolution of electroexplosive zinc nanoparticles (62 nm) in the synthetic alveolar has been studied. The evidence of the total solubility (99%) of metal nanopowders in the synthetic alveolar fluid had been demonstrated with the help of the stripping voltammetry. Alongside, the mechanism of zinc nanoparticles dissolution related to the electroexplosive zinc nanoparticles completely dissolving in the synthetic alveolar fluid has been proposed.

Dispersion of ZrO2 and Y2O3 nanopowders in physiological suspensions

The dispersion of suspensions based on nanostructured powders (ZrO2 and Y2O3) and the simplest physiological fluids (phosphate buffering saline, glucose solution, water) in terms of their use in ecotoxicological tests was studied. Using the scanning electron microscopy and laser diffraction, an increase in the size of particles and agglomerates in the suspensions in 2-11 times was shown. The particle size distribution in the suspensions was characterized by a single peak, but its magnitude and width varied ambiguously upon standing suspensions in time. It was shown experimentally that the average size of the dispersed phase could rapidly grow in the DW-suspension, could be stabilized in PBS-suspension and might decrease with time in Gl-suspension. By electro-acoustic method it was shown that the Zeta- potential on the solid/liquid boundary in the study varied over a wide range of values from - 200 to + 200, and the nature of change - a jump. This demonstrated the instability of the suspensions based on NP-ZrO2 and NP-Y2O3.

Potassium layered polytitanates influence on low-pressure polyethylene properties in wide concentrations range

Thermoplastic composites based on low-pressure polyethylene and layered potassium titanates have been made in the work. We have shown the possibility to processing the composites into the products by injection molding at polytitanates content up to 50%wt. Technological properties of composites at low concentrations of filler are established. Layered potassium polytitanates influence on the mechanical and thermophysical properties of low-pressure polyethylene in a wide range of concentrations is investigated: from 1 to 50 %wt. Essential increase of complex of mechanical properties of polyethylene at introduction of small amounts of layered potassium polytitanates is shown. Due to the layered structure of the potassium polytitanates with particle size of about 500 nm in diameter and a thickness of less than 10 nm durability to shock loads increase comparable to the results of the introduction of fibrous potassium hexatitanates is reached.

Secondary polyvinyl butyral modified with potassium polytitanate for coatings with improved mechanical properties

The technology of laminated glass is accompanied with a large amount of polyvinyl butyral wastes, which are used for recycling due to mechanical properties of recycled PVB as these properties are lower than those of the original polymer. The properties of composite coatings based on secondary polyvinyl butyral modified with potassium polytitanate were investigated. The composite coating was obtained by polyvinyl butyral dissolved in ethyl alcohol and then dispersed potassium polytitanate into a solution. The resulting suspension was poured onto the surface of a solid substrate and then dried. The research shows that the surface modification of potassium polytitanate with different coupling agents significantly improves the polymer composite mechanical properties. The investigation of various homogenization techniques established a possibility for a significant improvement in the properties of a polyvinyl butyral composite by treatment in a ball mill. The mechanism interactions among the coupling agents, b...