Alteration of Hordeum vulgare and Sinapis alba germination and early growth in response to airborne low-metallic automotive brake wear debris.

Road transportation significantly contributes to environmental pollution, both in terms of exhaust and non-exhaust (brake wear) emissions. As was proven, brake wear debris is released in a wide variety of sizes, shapes, and compositions. Although studies confirming the possible adverse health and environmental impact of brake wear debris were published, there is no standardized methodology for their toxicity testing, and most studies focus only on one type of brake pad and/or one test. The lack of methodology is also related to the very small amount of material released during the laboratory testing. For these reasons, this study deals with the mixture of airborne brake wear debris from several commonly used low-metallic brake pads collected following the dynamometer testing. The mixture was chosen for better simulation of the actual state in the environment and to collect a sufficient amount of particles for thorough characterization (SEM, XRPD, XRF, chromatography, and particle size distribution) and phytotoxicity testing. The particle size distribution measurement revealed a wide range of particle sizes from nanometers to hundreds of nanometers, elemental and phase analysis determined the standard elements and compounds used in the brake pad formulation. The Hordeum vulgare and Sinapis alba were chosen as representatives of monocotyledonous and dicotyledonous plants. The germination was not significantly affected by the suspension of brake wear debris; however, the root elongation was negatively influenced in both cases. Sinapis alba (IC50 = 23.13 g L-1) was more affected than Hordeum vulgare (IC50 was not found in the studied concentration range) the growth of which was even slightly stimulated in the lowest concentrations of brake wear debris. The plant biomass was also negatively affected in the case of Sinapis alba, where the IC50 values of wet and dry roots were determined to be 44.83 g L-1 and 86.86 g L-1, respectively.

Effects of emulsion, dispersion, and blend electrospinning on hyaluronic acid nanofibers with incorporated antiseptics.

Nanofibrous materials are used in drug delivery as carriers of active ingredients. These can be incorporated into the materials with various electrospinning methods that differ mainly in the way spinning solutions are prepared. Each method affects primarily the encapsulation efficiency and distribution of active ingredients in the materials. This study focuses on the incorporation of octenidine dihydrochloride (OCT) and triclosan (TRI) into nanofibrous materials electrospun from native hyaluronic acid emulsions, dispersions, and blends. OCT had no substantial effect on fiber morphology, which is affected by the solvent system. All OCT encapsulation efficiencies were comparable (approximately 90%). TRI encapsulation efficiencies varied greatly depending on the method used. Merely 3% of TRI was encapsulated when it was spun from a dispersion. Encapsulation efficiency was higher, and TRI was incorporated in clusters when an emulsion was used. The best result was achieved with a blend, in which case 96% of TRI was encapsulated.

Antimicrobial nanofibrous mats with controllable drug release produced from hydrophobized hyaluronan.

Due to their large active surface, high loading efficiency, and tunable dissolution profiles, nanofibrous mats are often cited as promising drug carriers or antimicrobial membranes. Hyaluronic acid has outstanding biocompatibility, but it is hydrophilic. Nanofibrous structures made from hyaluronan dissolve immediately, making them unsuitable for controlled drug release and longer applications. We aimed to prepare a hyaluronan-based antimicrobial nanofibrous material, which would retain its integrity in aqueous environments. Self-supporting nanofibrous mats containing octenidine dihydrochloride or triclosan were produced by electrospinning from hydrophobized hyaluronan modified with a symmetric lauric acid anhydride. The nanofibrous mats required no cross-linking to be stable in PBS for 7 days. The encapsulation efficiency of antiseptics was nearly 100%. Minimal release of octenidine was observed, while up to 30% of triclosan was gradually released in 72 h. The nanofibrous materials exhibited antimicrobial activity, the fibroblast viability was directly dependent on the antiseptic content and its release.

Preparation of highly wettable coatings on Ti-6Al-4V ELI alloy for traumatological implants using micro-arc oxidation in an alkaline electrolyte.

Pulsed micro-arc oxidation (MAO) in a strongly alkaline electrolyte (pH > 13), consisting of Na2SiO3⋅9H2O and NaOH, was used to form a thin porous oxide coating consisting of two layers differing in chemical and phase composition. The unique procedure, combining MAO and removal of the outer layer by blasting, enables to prepare a coating suitable for application in temporary traumatological implants. A bilayer formed in an alkaline electrolyte environment during the application of MAO enables the formation of a wear-resistant layer with silicon incorporated in the oxide phase. Following the removal of the outer rutile-containing porous layer, the required coating properties for traumatological applications were determined. The prepared surfaces were characterized by scanning electron microscopy, X-ray diffraction patterns, X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. Cytocompatibility was evaluated using human osteoblast-like Saos-2 cells. The newly-developed surface modifications of Ti-6Al-4V ELI alloy performed satisfactorily in all cellular tests in comparison with MAO-untreated alloy and standard tissue culture plastic. High cell viability was supported, but the modifications allowed only relatively slow cell proliferation, and showed only moderate osseointegration potential without significant support for matrix mineralization. Materials with these properties are promising for utilization in temporary traumatological implants.

Electrospinning of Fibrous Layers Containing an Antibacterial Chlorhexidine/Kaolinite Composite.

The aim of this study was to prepare self-supporting homogeneous nano/microfibrous layers with a content of the clay mineral kaolinite and kaolinite modified with the antibacterial agent chlorhexidine (CH). Fibers were made of hydrophobic polymers-polyurethane and polycaprolactone. Polymer suspensions for electrospinning contained 2, 5, and 8 wt % (relative to the total weight of the suspension) of kaolinite or CH/kaolinite and were electrospun using 4SPIN LAB. The morphology of prepared fibrous layers was characterized using scanning electron microscopy; energy-dispersive X-ray spectroscopy mapping and Raman spectroscopy were used to confirm the presence and distribution of kaolinite in the layers. Fiber diameters decreased after adding kaolinite or CH/kaolinite and ranged from 600 nm to 5 µm. Antibacterial CH was found in kaolinite itself as well as separately in the fibers (result of imperfect bonding of CH onto the surface of kaolinite). The encapsulation efficiency of all samples exceeded 64%, and the highest efficiency was observed in samples with 2 wt % CH/kaolinite. Samples containing CH exhibited good antibacterial activity against Staphylococcus aureus, and the effectiveness of which was affected by the concentration of the antibacterial agent. The release of CH was very slow, and there was no initial burst release. Overall, no more than 5% of the CH was released over a course of 168 h. The Korsmeyer-Peppas model revealed that CH is released by a diffusion mechanism.

Phytotoxicity of ZnO/kaolinite nanocomposite-is anchoring the right way to lower environmental risk?

The importance of studies on photoactive zinc oxide nanoparticles (ZnO NPs) increases with increasing environmental pollution. Since the ZnO NPs (and NPs in general) also pose an environmental risk, and since an understanding of the risk is still not sufficient, it is important to prevent their spread into the environment. Anchoring on phyllosilicate particles of micrometric size is considered to be a useful way to address this problem, however, so far mainly on the basis of leaching tests in pure water. In the present study, the phytotoxicity of kaolinite/ZnO NP (10, 30, and 50 wt.%) nanocomposites in concentrations 10, 100, and 1000 mg/dm3 tested on white mustard (Sinapis alba) seedlings was found to be higher (relative lengths of roots are ~ 1.4 times lower) compared with seedlings treated with pristine ZnO NPs. The amount of Zn accumulated from the nanocomposites in white mustard tissues was ~ 2 times higher than can be expected based on the ZnO content in the nanocomposites compared with the ZnO content (100 wt.%) in pristine ZnO NPs. For the false fox-sedge (Carex otrubae) plants, the amount of Zn accumulated in roots and leaves was ~ 2.25 times higher and ~ 2.85 times higher, respectively, compared with that of the pristine ZnO NPs (with respect to the ZnO content). Increased phytotoxicity of the nanocomposites and higher uptake of Zn by plants from the nanocomposites in comparison with pristine ZnO NPs suggest that the immobilization of ZnO NPs on the kaolinite does not reduce the environmental risk.

Ti and Zn Content in Moss Shoots After Exposure to TiO2 and ZnO Nanoparticles: Biomonitoring Possibilities.

To assess the uptake of nanoparticles by moss shoots and the possibility of biomonitoring the moss of nanoparticle pollution, two moss species frequently used in biomonitoring surveys [Hylocomium splendens (Hedw.) Schimp. and Pleurozium schreberi (Brid.) Mitt.] were repeatedly exposed to known concentrations of either nano-TiO2 or nano-ZnO suspensions. The interspecies differences were assessed by exposing both the species to 1 g L-1 nano-ZnO suspension, H. splendens samples were also exposed to either 0.1 g L-1 or 1 g L-1 suspension of nano TiO2. The exposed samples were analysed for Zn or Ti content using Inductively Coupled Plasma-Atomic Emission Spectroscopy. Both species showed a similar accumulation pattern, H. splendens being a slightly better accumulator. The washing suggests that Ti successfully penetrated the interior of the gametophyte. Since the relationship between the exposure and accumulation is linear, moss biomonitoring is, hereby, considered to be a viable, novel technique in nanoparticle pollution assessment.

Effects of binder choice in converter and blast furnace sludge briquette preparation: Environmental and practical implications.

Blast furnace and converter sludges are fine-grained waste materials characterized as dangerous waste with a negative impact on the environment. One way of recycling of such materials is briquetting followed by reuse of the material in the blast furnace. In the briquetting process, an important step is the choice of the binder suitable for manufacturing the briquettes with suitable mechanical properties. In this work, the effect of the binder choice (laundry starch UNIPRET, Portland cement) on the reduction of iron oxides in the assessed waste materials during thermal treatment (900, 1000, 1100 °C) is evaluated. Simultaneously, the effect of the binder choice on the amount and composition of the resulting waste gas was evaluated as well as its possible impact on the environment. The performed experiments proved the mutual relationship between the level of iron oxides to metal iron conversion, the binder content and retention temperature. Type of binder also affected the volume of the resulting waste gas. Factor analysis for mixed data (FAMD) proved that the resulting concentrations of the assessed hydrocarbons were correlated (apart from ethyne) and that they are closely associated with the binder applied. Conversely, the concentrations of ethyne, carbon monoxide and carbon dioxide were not associated with the binder but with the retention temperature. FAMD did not show any direct effect of final retention temperature on the amount of the rest of the resulting hydrocarbons. In comparison with the starch-containing briquettes, the cement-containing briquettes were also proved to lead to lower resulting concentrations of PAHs in the waste gas.

Iron-based granules in body of bumblebees.

The paper deals with the presence of iron-based granules in body parts of bumblebees. Two groups of bumblebees were collected from their natural habitat, industrial landscape, and from a breeding station. Detection of the magnetic particles was performed by a vibratory magnetometer and their morphology and elemental composition was analysed by scanning electron microscopy with EDX microanalysis. By means of the EDX spectra, wild bumblebees were found to have many magnetic and non-magnetic particles on their body, containing Fe, O, Al, Si, Bi, Mg, K, and Ni, likely having origin in the industrial pollution of the environment. In the case of bred bumblebees the presence of iron-rich granules, which occurred more abundantly in subsurface tissues on the head and wings, was observed. Phase analysis based on X-ray diffraction shows that iron-based granules contain magnetite and wuestite and Mössbauer spectroscopy admits a superparamagnetic form of these minerals. Magnetoreception, i.e. the sensory function of these granules, is discussed within the paper.