List of Abstracts 2022: POSTER SESSION D
Date: October 20, 2022
The diploma thesis deals with the toxic effect of nanotextiles as waste from respirators and face masks. The introduction of the thesis is focused on ecotoxicology and basic ecotoxicological tests according to available European standards and Czech legislation. The second chapter describes the production and other characteristics of the nonwovens that were tested. The theoretical part concludes with a review of foreign studies that have also dealt with testing of micro- and nano-plastics on various organisms. The experimental part presents specific experimental characteristics of the textiles and then presents individual tests. Seeds of plants growing in the Czech Republic, aquatic organisms Lemna minor L. and crustaceans Daphnia magna were tested. In all cases, the tested non-woven fabrics had a non-toxic effect on the organisms, but it cannot be confirmed that there is no reaction. Further tests will be carried out to clarify the effects of the nonwovens on the test organisms.
The usage of organic semiconductors in the construction of bioelectronic devices represents a very promising alternative to metal electrode systems and traditional inorganic semiconductors. For these devices, the biocompatibility of the interface between the electronic element and living cells is a critical parameter. Poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) is probably the most successful conductive polymer in terms of practical application. It has many unique properties, such as excellent optical transparency in the visible light range, high electrical conductivity, and good physical and chemical stability in air. However, the issue of long-term biocompatibility of PEDOT:PSS is not completely resolved. Therefore, new ways to improve biocompatibility are constantly being sought. DNA biofunctionalization, for example, seems promising.
In our study, we monitored and compared the toxicity of PEDOT:PSS, PEDOT:DNA and polypyrrole:DNA (PPy:DNA) films deposited on a glass substrate on the NIH3T3 mouse fibroblast cell line. We focused on the morphological changes of cells after contact with the film samples observable by the fluorescence optical microscopy and atomic force microscopy (AFM). Moreover, acute and long-term viability of the cells were determined by measuring the metabolic activity of cells (MTT test), as well as by live / dead viability measurement using flow cytometry. The obtained results show that the PEDOT:DNA and PPy:DNA combination represents a promising way to increasing conductivity while keeping the biocompatibility.
ACKNOWLEDGEMENTS: This work was supported by the project: ERDF project “Development of pre-applied research in nanotechnology and biotechnology” (No. CZ.02.1.01/0.0/0.0/17_048/0007323) a EnzymBiokat - EFRE project (GZ2018-98279-2).
Here we present study on the toxicity evaluation of two iron-based nanoparticles: nFe3O4, and nZVI on freshwater microalgae, Chlamydomonas reinhardtii CC-5325. Microalgae response (phytochrome analysis including total chlorophyll/carotenoids content, chlorophyll fluorescence and total viable cell numbers) to the nanoparticles exposure (100 mg/L) was monitored up to 120 hours. Based on phytochrome analyses performed, almost no significant impact can be found. However, physiological alteration and the total viable cell numbers revealed a certain degree of inhibition effect showing altered cell shape, and higher number of dead cells after the exposure to both NPs. The dead cell numbers increased by 4-fold (consisted of 31% of dead cells from viable cells) within one hour after the exposure to nFe3O4, while nZVI caused rather slow inhibition effect and persisted until 48 h, with the highest dead cell 7-fold increase (44% of dead cells) comparing to the initial time point of nZVI exposure. In a series of experiments performed, the results may justify that exposure of these two NPs initially slightly inhibited C. reinhardtii, however the culture was able to recover towards the end of the study, because of new cell generation and nZVI oxidation.
A large part of composite components undergoes a finishing machining process before assembly. Composite systems - carbon fiber/epoxy resin behave differently than metals during machining. The released polymer par-ticles, particularly the carbon fiber segments, can affect human health. The presented study deals with the release of fibers from the composite materials - the formation of chips and their destruction or breaking into shorter seg-ments related to the machining process. Composite samples with recycled carbon fibers and carbon roving were subjected to selected machining processes. The scanning electron microscope was used to characterize the car-bon fibers used in both types, especially to study the destruction of fibrous structures formed during machining processes. Based on the study, it was found that at the ends of the carbon fibers, there is a cleavage of microscopic fragments whose dimensions range from 2 to 3 µm, which is the WHO limit size for particles that can be in-haled. Dimensions of separate surface layers are micrometers in terms of length/width and the sub-micrometer level in terms of their thickness. Layers separated from the surface of the carbon fiber were found both in the case of the use of new carbon fibers and recycled carbon fibers.
Exposure to particulate air pollution has been associated with a variety of health problems. One of the main sources of metal-rich airborne particulate pollution in roadside environments are brake-wear emissions. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), X-ray powder diffraction (XRD) was used to make quantitative evaluation wear particles in two samples. Sizes, morphologies, oxidation state, and trace element compositions of wear particles investigated using combination of several methods revealed high concentrations of Fe species and phases, often associated with carbonaceous material. SEM and TEM observations show that brake wear particles with a size of tens to hundreds of nm mainly form particle agglomerates. However, ultrafine (<100 nm) particles are likely to pose a health threat after inhalation and/or ingestion.
The usage of pharmaceuticals increases worldwide every year. The residues of these substances are excreted by the human or animal bodies and thus come into direct contact with the environment, mainly soils and ground water. The accumulation of pharmaceuticals in natural ecosystems may be problematic in the future therefore the knowledge of their behavior, transport and interactions in the ecosystems is essential for their treatment. The most reactive substances in soils are humic as well as fulvic substances. Two fulvic acids stand as the model reactants with different pharmaceuticals in this study. These reactive compounds contain several kinds of active functional groups, such as hydrophilic hydroxylic or carboxylic groups, and also diverse hydrophobic structures. The interactions between fulvic acids and solutions of pure drugs were studied by isothermal titration calorimetry. The aim of the study was to observe the heat effects of the interactions and to describe the intensity of the binding process.
Currently, microscopic or spectroscopic methods (SEM, TEM, DLS...) are used to analyse nanoparticles in the environment. However, these methods are usually very expensive and demanding in terms of instrumentation, requiring complex sample preparation, complicated evaluation of experimental data, etc. Moreover, in the scientific literature, the information regarding nanoparticle analyses in the RU is rather sketchy and incomplete. This is also noted in the "Communication from the Commission to the European Parliament, the Council and the European Economic and Social Committee - Second Regulatory Review on Nanomaterials" in 2012.
The so-called nano-impacts method was tested as part of the presented work. This is based on the presence of the nano-electrode in the solution (Pt electrode, diameter 10 µm, active area 7.85x10-5 mm2) on which an appropriate potential is set. When the the brown motion causes the nanoparticle to strike the electrode's surface, a redox reaction takes place, acting on the current's dependence on potential as a sharp peak. Both qualitative and quantitative characteristics can subsequently be derived from peak parameters and peak frequency.
The results of the analysis of the nanoparticle content of palladium, copper and iron in aqueous solutions at 50°C are presented, the utility of the methodology and the linear nature of the calibration curve are demonstrated.
Organic semiconductors are materials primarily based on carbon and hydrogen, exhibiting semiconductor properties. Due to their soft, elastic, and carbon-based character, organic semiconductors provide an ideal interface with biological tissues, which makes them promising for various applications in the field of bioelectronics. Epindolidione and quinacridone are commercially available organic semiconductor hydrogen-bonded pigments. Despite their suitable properties for bioelectronic applications (stability in aqueous environments, direct bioconjugation, low cost), their biocompatibility has not been thoroughly examined. In the present study, epindolidione and quinacridone thin layers were applied on cell culture wells using spin coating technique. Cell viability, morphology and attachment capability were evaluated in NIH3T3 mouse fibroblasts after 24-96h exposure. LIVE/DEAD assay measured by flow cytometry was used to assess cytotoxicity in cells cultivated on epindolidione or quinacridone layers and in cell culture medium harvested after 24h incubation in pigments-covered plates. Adhesion properties and morphology of cells grown on pigments-covered plates for 24h and then seeded on non-coated plates were monitored for up to 72h using optical microscopy. In summary, no differences were observed in viability, cell morphology or attachment capability between control cells and cells grown on epindolidione or quinacridone thin layers or cells cultivated with medium harvested from epindolidione or quinacridone layers. Our results suggest that epindolidione and quinacridone are highly biocompatible. The lack of toxicity together with low cost and availability indicate high application potential of epindolidione or quinacridone in next-generation bioelectronic devices. Acknowledgment: ERDF/ESF project “Nano4Future” (CZ.02.1.01/0.0/0.0/16_019/0000754) and OPVVV “Development of pre-applied research in nanotechnology and biotechnology” CZ.02.1.01/0.0/0.0/17_048/0007323.
Environmental and nanomaterial research is highly dependent on the availability of specific analytical tools. However, even well-equipped universities and research centres often lack certain equipment and experienced staff to perform all analyses needed. External analyses might be costly and can take a lot of time. Research Infrastructure NanoEnviCz (RI NEC) was founded to address these issues and support cooperation among Czech and foreign researchers. Any student, researcher or company working within environmental and nanomaterial sciences can register and apply for any analysis available at six Czech partner academic institutions for free. Not only does it help students and researchers with their work, but it also enhances cooperation between academia and industry.
ACKNOWLEDGEMENTS: The authors acknowledge the assistance provided by the Research Infrastructure NanoEnviCz, supported by the Ministry of Education, Youth and Sports of the Czech Republic under Project No. LM2018124.