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.

Synergistic Combination of Antimicrobial Peptides and Cationic Polyitaconates in Multifunctional PLA Fibers.

Combining different antimicrobial agents has emerged as a promising strategy to enhance efficacy and address resistance evolution. In this study, we investigated the synergistic antimicrobial effect of a cationic biobased polymer and the antimicrobial peptide (AMP) temporin L, with the goal of developing multifunctional electrospun fibers for potential biomedical applications, particularly in wound dressing. A clickable polymer with pendent alkyne groups was synthesized by using a biobased itaconic acid building block. Subsequently, the polymer was functionalized through click chemistry with thiazolium groups derived from vitamin B1 (PTTIQ), as well as a combination of thiazolium and AMP temporin L, resulting in a conjugate polymer-peptide (PTTIQ-AMP). The individual and combined effects of the cationic PTTIQ, Temporin L, and PTTIQ-AMP were evaluated against Gram-positive and Gram-negative bacteria as well as Candida species. The results demonstrated that most combinations exhibited an indifferent effect, whereas the covalently conjugated PTTIQ-AMP displayed an antagonistic effect, potentially attributed to the aggregation process. Both antimicrobial compounds, PTTIQ and temporin L, were incorporated into poly(lactic acid) electrospun fibers using the supercritical solvent impregnation method. This approach yielded fibers with improved antibacterial performance, as a result of the potent activity exerted by the AMP and the nonleaching nature of the cationic polymer, thereby enhancing long-term effectiveness.

Biocompatibility and biocidal effects of modified polylactide composites.

Polylactide (PLA) materials treated with antimicrobial fillers represent a suitable alternative to the production of medical devices. Their advantage is that they can prevent the growth of microorganisms and the formation of microbial biofilms on the surface and around composites. The work is focused on the evaluation of biocompatibility and biocide effect of PLA composite films filled with vermiculite and graphene oxide modified with silver (Ag+ and Ag nanoparticles), hexadecylpyridinium (HDP) and hexadecyltrimethylammonium (HDTMA) cations and their degradation leachates monitored at 1-3-6-month intervals. The antimicrobial effect of the leachates was detected by microdilution methods on gram-negative (Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis), gram-positive (Staphylococcus aureus, Streptococcus salivarius) bacteria and yeast (Candida albicans). The biocidal effect of composites on biofilm formation on the surface of composites was monitored by Christensen method and autoaggregation and motility tests. The biocompatibility of the composite and the leachates was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) cytotoxicity assay. The evaluation of the antimicrobial effect of the leachates demonstrated that leachates of PLA composite filled with graphene oxide and Ag+ showed a stronger antimicrobial effect than leachates of PLA composite filled with vermiculite and Ag+ and Ag nanoparticles. The leachates of PLA composites containing vermiculite with HDP and HDTMA cations had a higher antimicrobial effect on G+ bacteria and yeast than G- bacteria. Bacterial growth, biofilm formation, autoaggregation and motility of the tested bacteria were most inhibited by the composite with vermiculite and Ag+ and Ag nanoparticles. Even after a 6-month degradation of this composite, bacterial growth and biofilm formation continued to be strongly inhibited up to 42 and 91%, respectively. The cytotoxic effect was proved only in the leachate of the composite with vermiculite containing HDP after 6 months of its degradation. Tests evaluating the biocompatibility of materials have shown that the vermiculite is the most preferred carrier and can be used in the future to bind other compounds. The study confirmed that PLA composite filled with vermiculite and Ag+ and Ag nanoparticles was the most stable and effective composite with the best biocompatible and biocidal properties.

Effective and reproducible biosynthesis of nanogold-composite catalyst for paracetamol oxidation.

Pharmaceutical products are some of the most serious emergent pollutants in the environment, especially nowadays of the COVID-19 pandemic. In this study, nanogold-composite was prepared, and its catalytic activity for paracetamol degradation was investigated. Moreover, for the first time, recycled waste diatomite earth (WDE) from beer filtration was used for reproducible gold nanoparticle (Au NPs) preparation. We studied Au NPs by various psychical-chemical and analytical methods. Transmission and scanning electron microscopy were used for nanogold-composite morphology, size and shape characterization. Total element concentrations were determined using inductively coupled plasma mass and X-ray fluorescence spectrometry. X-ray powder diffraction analysis was used for crystal structure characterization of samples. Fourier transform infrared spectrometer was used to study the chemical changes before and after Au NP formation. The results revealed that the WDE served as both a reducing and a stabilizing agent for crystalline spherical 30 nm Au NPs as well as acting as a direct support matrix. The kinetics of paracetamol degradation was studied by high-performance liquid chromatography with a photodiode array detector. The conversion of paracetamol was 62% and 67% after 72 h in the absence or presence of light irradiation, respectively, with 0.0126 h-1 and 0.0148 h-1 reaction rate constants. The presented study demonstrates the successful use of waste material from the food industry for nanogold-composite preparation and its application as a promising catalyst in paracetamol removal.

Advances in Use of Nanomaterials for Musculoskeletal Regeneration.

Since the worldwide incidence of bone disorders and cartilage damage has been increasing and traditional therapy has reached its limits, nanomaterials can provide a new strategy in the regeneration of bones and cartilage. The nanoscale modifies the properties of materials, and many of the recently prepared nanocomposites can be used in tissue engineering as scaffolds for the development of biomimetic materials involved in the repair and healing of damaged tissues and organs. In addition, some nanomaterials represent a noteworthy alternative for treatment and alleviating inflammation or infections caused by microbial pathogens. On the other hand, some nanomaterials induce inflammation processes, especially by the generation of reactive oxygen species. Therefore, it is necessary to know and understand their effects in living systems and use surface modifications to prevent these negative effects. This contribution is focused on nanostructured scaffolds, providing a closer structural support approximation to native tissue architecture for cells and regulating cell proliferation, differentiation, and migration, which results in cartilage and bone healing and regeneration.

Colloidal stability of phytosynthesised gold nanoparticles and their catalytic effects for nerve agent degradation.

Herein, Tilia sp. bract leachate was used as the reducing agent for Au nanoparticles (Au NPs) phytosynthesis. The colloidal properties of the prepared Au NPs were determined to confirm their stability over time, and the NPs were then used as active catalysts in soman nerve agent degradation. The Au NPs characterisation, reproducibility and stability studies were performed under transmission electron microscopy, ultraviolet visible spectroscopy and with ζ-potential measurements. The reaction kinetics was detected by gas chromatography coupled with mass spectrometry detector and solid-phase micro-extraction to confirm the Au NPs applicability in soman hydrolysis. The 'green' phytosynthetic formation of colloidal crystalline Au NPs with dominant quasi-spherical shape and 55 ± 10 nm diameter was successfully achieved, and there were no significant differences in morphology, ζ-potential or absorbance values observed during the 5-week period. This verified the prepared colloids' long-term stability. The soman nerve agent was degraded to non-toxic substances within 24 h, with 0.2156 h-1 reaction rate constant. These results confirmed bio-nanotechnology's great potential in preparation of stable and functional nanocatalysts for degradation of hazardous substances, including chemical warfare agents.

Chronic Inflammatory Diseases, Anti-Inflammatory Agents and Their Delivery Nanosystems.

Inflammatory diseases, whether caused by excessive stress on certain tissues/parts of the body or arising from infections accompanying autoimmune or secondary diseases, have become a problem, especially in the Western world today. Whether these are inflammations of visceral organs, joints, bones, or the like, they are always a physiological reaction of the body, which always tries to eradicate noxious agents and restore tissue homeostasis. Unfortunately, this often results in damage, often irreversible, to the affected tissues. Nevertheless, these inflammatory reactions of the body are the results of excessive stress, strain, and the generally unhealthy environment, in which the people of Western civilization live. The pathophysiology and pathobiochemistry of inflammatory/autoimmune processes are being studied in deep detail, and pharmaceutical companies are constantly developing new drugs that modulate/suppress inflammatory responses and endogenous pro-inflammatory agents. In addition to new specifically targeted drugs for a variety of pro-inflammatory agents, a strategy can be found for the use of older drugs, which are formulated into special nanodrug delivery systems with targeted distribution and often modified release. This contribution summarizes the current state of research and development of nanoformulated anti-inflammatory agents from both conventional drug classes and experimental drugs or dietary supplements used to alleviate inflammatory reactions.

Chemical Hydrogels Bearing Thiazolium Groups with a Broad Spectrum of Antimicrobial Behavior.

Several hydrogels based on 2-hydroxyethyl methacrylate and a methacrylic monomer containing a thiazole group in its lateral chain have been prepared by thermal polymerization at 60 °C in water solution varying the chemical composition of the gels. The posterior quaternization of the thiazole groups with methyl iodine has rendered positively charged hydrogels with potential antimicrobial activity. This modification has been structurally characterized by infrared spectroscopy, whereas the thermal stability of all hydrogels has been studied by thermal degradation in inert atmosphere. The swelling behavior in distilled water and the rheology of the different hydrogels have been analyzed as a function of 2-(4-methylthiazol-5-yl)ethyl methacrylate (MTA) monomer content as well as its methylation. Finally, the active character of hydrogels against Gram-positive and Gram-negative bacteria and fungi has been evaluated, revealing excellent antimicrobial activity against all tested microorganisms. The methylated hydrogels could be used as potential materials for wound healing or contact lens applications.

Antibacterial Character of Cationic Polymers Attached to Carbon-Based Nanomaterials.

The preparation of hybrid polymeric systems based on carbon derivatives with a cationic polymer is described. The polymer used is a copolymer of a quaternizable methacrylic monomer with another dopamine-based monomer capable of anchoring to carbon compounds. Graphene oxide and graphene as well as hybrid polymeric systems were widely characterized by infrared, Raman and photoemission X-ray spectroscopies, electron scanning microscopy, zeta potential and thermal degradation. These allowed confirming the attachment of copolymer onto carbonaceous materials. Besides, the antimicrobial activity of hybrid polymeric systems was tested against Gram positive Staphylococcus aureus and Staphylococcus epidermidis and Gram negative Escherichia coli and Pseudomonas aeruginosa bacteria. The results showed the antibacterial character of these hybrid systems.

Biodegradation of Reactive Orange 16 azo dye by simultaneous action of Pleurotus ostreatus and the yeast Candida zeylanoides.

The purpose was to investigate a simultaneous biodegradation of the recalcitrant monoazo dye Reactive Orange 16 (RO16) in a mixed culture consisting of a biofilm of Pleurotus ostreatus-colonizing polyamide carrier and a suspension of the yeast Candida zeylanoides to see their biological interactions and possible synergistic action during degradation. Decolorization in the mixed culture was more effective than in the fungal monoculture, the respective decolorizations reaching 87.5% and 70% on day 11. The proliferation of yeast was reduced compared with the C. zeylanoides monoculture but enabled the yeast to participate in decolorization. The interaction of P. ostreatus with the yeast resulted in a gradual decrease of fungal manganese-dependent peroxidase (MnP) and laccase activities. Gas chromatography-mass spectrometry (GC-MS) analysis of the degradation products brought evidence that P. ostreatus split the dye molecule asymmetrically to provide 4-(ethenylsulfonyl) benzene whose concentration was much decreased in the mixed culture suggesting its increased metabolization in the presence of the yeast. In contrast, C. zeylanoides split the azo bond symmetrically producing the metabolites 4-(ethenylsulfonyl) aniline and α-hydroxybenzenepropanoic acid. Those metabolites were rapidly degraded in the mixed culture. A novel aspect is represented by the evidence of a mutual cooperative action of the fungal and yeast microorganisms in the mixed culture resulting in rapid decolorization and degradation of the dye.

Adsorption of nerve agent simulants onto vermiculite structure: Experiments and modelling.

Chemical warfare agents are still a threat to humanity despite the existence of a ban on their production and use. There are many new materials that have been experimentally verified to be effective in degrading and eliminating various chemical warfare agents; however, clay minerals still remain very effective, environmentally friendly and not expensive. Vermiculites modified with hexadecylpyridinium, hexadecyltrimethylammonium and tetramethylammonium cations were used for static sorption of vapours of two simulants of nerve agents: dimethyl methyl phosphonate and diethyl ethyl phosphonate. The materials before and after sorption were characterized using infrared spectroscopy, X-ray diffraction and carbon phase analysis. The breakthrough time and capture of simulants were measured using dynamic sorption test. Molecular modelling was used to confirm the experimental results and provide a deeper insight into the structure of the materials and sorption processes.

Graphenic Materials for Biomedical Applications.

Graphene-based nanomaterials have been intensively studied for their properties, modifications, and application potential. Biomedical applications are one of the main directions of research in this field. This review summarizes the research results which were obtained in the last two years (2017-2019), especially those related to drug/gene/protein delivery systems and materials with antimicrobial properties. Due to the large number of studies in the area of carbon nanomaterials, attention here is focused only on 2D structures, i.e. graphene, graphene oxide, and reduced graphene oxide.

Biocompatible Polymer Materials with Antimicrobial Properties for Preparation of Stents.

Biodegradable polymers are promising materials for use in medical applications such as stents. Their properties are comparable to commercially available resistant metal and polymeric stents, which have several major problems, such as stent migration and stent clogging due to microbial biofilm. Consequently, conventional stents have to be removed operatively from the patient's body, which presents a number of complications and can also endanger the patient's life. Biodegradable stents disintegrate into basic substances that decompose in the human body, and no surgery is required. This review focuses on the specific use of stents in the human body, the problems of microbial biofilm, and possibilities of preventing microbial growth by modifying polymers with antimicrobial agents.

From biotechnology principles to functional and low-cost metallic bionanocatalysts.

Chemical, physical and mechanical methods of nanomaterial preparation are still regarded as mainstream methods, and the scientific community continues to search for new ways of nanomaterial preparation. The major objective of this review is to highlight the advantages of using green chemistry and bionanotechnology in the preparation of functional low-cost catalysts. Bionanotechnology employs biological principles and processes connected with bio-phase participation in both design and development of nano-structures and nano-materials, and the biosynthesis of metallic nanoparticles is becoming even more popular due to; (i) economic and ecologic effectiveness, (ii) simple one-step nanoparticle formation, stabilisation and biomass support and (iii) the possibility of bio-waste valorisation. Although it is quite difficult to determine the precise mechanisms in particular biosynthesis and research is performed with some risk in all trial and error experiments, there is also the incentive of understanding the exact mechanisms involved. This enables further optimisation of bionanoparticle preparation and increases their application potential. Moreover, it is very important in bionanotechnological procedures to ensure repeatability of the methods related to the recognised reaction mechanisms. This review, therefore, summarises the current state of nanoparticle biosynthesis. It then demonstrates the application of biosynthesised metallic nanoparticles in heterogeneous catalysis by identifying the many examples where bionanocatalysts have been successfully applied in model reactions. These describe the degradation of organic dyes, the reduction of aromatic nitro compounds, dehalogenation of chlorinated aromatic compounds, reduction of Cr(VI) and the synthesis of important commercial chemicals. To ensure sustainability, it is important to focus on nanomaterials that are capable of maintaining the important green chemistry principles directly from design inception to ultimate application.

Polylactide Composites Suitable for Medical Devices.

Biodegradable polymeric materials with antimicrobial surfaces could be a suitable alternative for production of medical devices, especially if they are prepared in form of composites containing functional matter. Their greatest advantage is that they do not need to be removed from patient's body and simultaneously they can prevent growth of biofilm. In this work, polymeric films of polylactide acid with biosynthetically prepared silver nanoparticles, commercial multiwall carbon nanotubes and organovermiculite with hexadecyltrimethylammonium bromide in various concentrations were prepared to get polylactide composite with antibacterial properties. The dispersibility of filler in matrix was one of the key issues to be controlled in nanocomposite. Using several analytical techniques and observing morphology of prepared composite it was found that best results provide organovermiculite filler. For the tests of functionality antimicrobial tests were performed.

Organovermiculite as Regenerable Nanostructured Adsorbent for Treatment of Heavily Polluted Waste Water from Coke Industry.

Organically modified vermiculites can be used as nanostructured adsorbents of organic compounds from waters or gaseous phases similarly as organically modified smectites or bentonites. There is a large amount of research data focused on adsorption properties of organoclays, however only a little information is about their post-sorption treatment. This work is focused on study of two possible ways of subsequent processing of organovermiculite after its use as sorbent for heavily polluted waste water. At first, the vermiculite modified with hexadecylpyridinium ions was used in batch static sorption against phenol ammonium water from the coke industry to get highly contaminated sorption material, especially containing organic hydrocarbons and their derivatives. The sorbent is known to have excellent sorption properties; however ecotoxicological characteristics of original material showed that sorbent had hazardous properties even before its utilization. For that reason, it was necessary to design a post-sorption treatment. Two possible methods of treatment were investigated, specifically solvent treatment (with dichloromethane) and thermal treatment (thermodesorption) at temperatures of 300 and 1100 °C, respectively. The treated materials were studied using infrared spectroscopy, X-ray diffraction and carbon phase analyses. The solvent treatment confirmed that it is possible to reuse modified vermiculite as adsorbent several times, although adsorption capacity after each extraction decreases. The thermal treatment at 300 °C was not sufficient to remove all organic compounds from the vermiculite structure; however at 1100 °C the only presence of magnesium silicate, magnesium aluminate and ferric oxide confirmed the formation of an inert material convenient for an environmentally harmless disposal of used adsorbent.

Effect of Milling and Annealing on Carbon-Silver System.

Mechanical treatment of graphite silver mixture followed by heat treatment showed morphology and structure changes of both components. Silver is being distributed over graphite flakes randomly with higher concentration on the edges and nanometric size, which was observed using scanning and transmission electron microscopy. The annealing temperature 1300 °C is higher than melting temperature of silver (961.8 °C) and base on phase diagram C-Ag (C. L. Chen, et al., Appl. Phys. Lett. 96, 253104 (2010).) silver is being transferred from liquid phase to solid phase at rapid cooling, which is giving various crystallinity.

Micronization of Ibuprofen Particles Using Supercritical Fluid Technology.

Most of drugs are only slightly soluble in the circulatory system of the human body. This reduces the efficiency of their use and that is why new ways how to increase their solubility are investigated. One way to improve the solubility of the drug is to reduce its particle size. Conventional techniques such as crushing or grinding usually do not guarantee a narrow particle size distribution, which is required for pharmaceuticals. Application of supercritical fluids, especially of supercritical CO2, seems to be convenient method for the preparation of pharmaceuticals submicron particles or nanoparticles. The method enables the preparation of particles in a narrow size distribution and at the same time it does not leave any unwanted residues of solvents or other chemicals. The aim of this work is the micronization of ibuprofen particles using the supercritical fluid and characterization of formed products. The micronization of the particles was done using commercially available device Spe-ed SFE-4 in rapid expansion of supercritical solution mode. The applied temperatures and pressures were 308.15 K and 313.15 K and 200, 250 and 300 bar. The prepared particles were characterized using methods of X-ray diffraction, infrared spectroscopy, particle size distribution, scanning electron microscopy and tests of dissolution and permeability. Mean particles size was reduced from 180 µm (original ibuprofen) to 2.8-7.3 µm of the processed samples. The dissolution test confirmed better solubility and the permeability of newly formed particles improved.

Phytosynthesis of Au and Au/ZrO2 bi-Phasic System Nanoparticles with Evaluation of Their Colloidal Stability.

Due to its easy availability, preparation, handling and non-toxic nature, Equisetum arvense horsetail extract was chosen as a reducing, stabilizing and functionalizing agent for Au and bi-phasic Au/ZrO2 nanoparticle phytosynthesis-inorganic nanoparticle synthesis mediated by plant extract. We studied Au and bi-phasic Au/ZrO2 nanoparticles in colloids by various physical-chemical and analytical methods over 5 weeks. Dynamic Light Scattering and Scanning Transmission Electron Microscopy compared core and hydrodynamic diameters of nanoparticles. ζ-potential measurement indirectly determined nanoparticles stability in liquid medium. Ultraviolet-Visible Spectroscopy characterized basic absorbance maxima for both Au and the bi-phasic Au/ZrO2 system. Finally, total metal concentration was determined using Inductively Coupled Plasma Mass Spectrometry. ζ-potential measurements proved satisfactory stability of both Au (-13.4 to -17 mV) and Au/ZrO2 nanoparticles (-14.1 to -17.5 mV) over the experimental period. Scanning Transmission Electron Microscopy with Selected Area Diffraction analysis confirmed nanoparticles crystalline nature, and we determined 24 nm and 40 nm core nanogold diameters in Au and Au/ZrO2 nanoparticle colloids. Dynamic light scattering analysis confirmed the dichotomy between particle sizes in liquid medium in the hundreds of nanometers measured, and long-term measurements confirmed reasonable colloid stability-a paramount parameter for potential nanoparticles applications; especially in heterogeneous catalysis.

Silver/Chitosan Antimicrobial Nanocomposites Coating for Medical Devices: Comparison of Nanofiller Effect Prepared via Chemical Reduction and Biosynthesis.

Medical devices have an essential part in healthcare system in recent years, such as usage of heart valves, several types of stents and implants devices in patients. However, bacterial infection of medical devices causes critical issues for patients due to attachment of bacteria and formation of biofilm onto the medical devices. Therefore, finding an effective antibacterial coating to prevent biofilm formation and infection is our goal. In this study, we developed silver/chitosan nanocomposites for antimicrobial coating system by chemical and green methods using sodium borohydride and linden extract, respectively. Silver is known as a strong inorganic antimicrobial agent to kill bacteria by inactivating enzymes and dysfunction bacterial cell membranes. By immobilizing silver nanoparticles on chitosan biopolymer can prevent agglomeration of nanoparticles, besides it can improve the biocompatibility. We characterized properties of our silver chitosan nanocomposites samples using particle size distribution, ultraviolet-visible spectroscopy, X-ray diffraction analysis and scanning electron microscopy. Effective antimicrobial film preventing biofilm formation on medical devices was designed. Antimicrobial testing confirmed antimicrobial properties however variable for each type of nanosilver.