Národní úložiště šedé literatury Nalezeno 10 záznamů.  Hledání trvalo 0.01 vteřin. 
Application potential of screening in vitro toxicological assays in qualitative risk assessment of nanomaterials
Závodná, Táňa ; Topinka, Jan ; Danihelka, J.
Undeniable benefits of engineered nanomaterials might be discredited by their potential enhanced or unexpected toxicity arising from nano-specific properties and behavior. An analysis of the applicability of the traditional chemical risk assessment approach in nanomaterials revealed high levels of uncertainty in both hazard characterization and exposure assessment due to the lack of relevant validated methods and reliable data. This indicates the limited capability of the conventional risk assessment approach to ensure the safe use of nanomaterials. Based on the identified uncertainties, the control banding approach was proposed as a suitable tool for preliminary qualitative risk assessment of nanomaterials in occupational settings. Control banding categorizes hazard and exposure into levels referred to as bands. The combination of the hazard and exposure bands results in a risk band determining the necessary degree of control and regulatory measures. To decrease the number of cases where, based on the precautionary principle, unavailable experimental or field data would lead to the assignment to the highest hazard category requiring costly exposure control, screening evaluation of nanomaterial toxicity was proposed as an additional decision criterion. For this purpose, a battery of in vitro toxicological assays enabling screening evaluation of potential toxic effects of NMs was proposed. The assays evaluate endpoints covering basic toxic effects of substances (cytotoxicity, genotoxicity), as well as known nonspecific mechanisms of toxicity typical for nanomaterials (oxidative stress, inflammation). The proposed risk management strategy is intended to assist small and medium-sized enterprises to implement adequate measures to ensure employee safety.
Ultrafine particles and their possible role in etiology and development of neurodegenerative diseases
Topinka, Jan ; Závodná, Táňa ; Rössnerová, Andrea ; Rössner ml., Pavel
Air pollutants have been shown to cause a vast amount of different adverse health effects. These effects include impairment of many respiratory (e.g. asthma, chronic obstructive pulmonary disease) and cardiovascular (ischemic heart disease, infarction, stroke) diseases. However, in recent years, the evidence showing effects beyond the lungs and circulatory system are becoming more evident. Neurological diseases, namely Alzheimer's disease (AD) has shown to be associated with living near traffic. However, reason for this has remained unresolved until today. Our new H2020 project TUBE aims on revealing the mechanisms of action of ultrafine particles involved in neurological diseases. The TUBE consortium includes experts in areas of aerosol technology, emission research, engine and fuel research, human clinical studies, epidemiology, emission inventories, inhalation toxicology, neurotoxicology and disease mechanism studies. This enables research of resolving the effects of nanoparticles from different traffic modes for both air quality and concomitant toxic effect of these air pollutants. We will investigate adverse effects of air pollutants using cell cultures, animal exposures and volunteered human exposures as well as the material from epidemiological cohort study. These are going to be compared according to inflammatory, cytotoxic and genotoxic changes and furthermore beyond the current state of the art to neurotoxic and brain health effects. With this approach, we are aiming to a comprehensive understanding of the adverse brain effects of nanoparticles from traffic.
Toxic responses in human lung epithelial cells (BEAS-2B) exposed to particulate matter exhaust emissions from gasoline and biogasoline
Závodná, Táňa ; Líbalová, Helena ; Vrbová, Kristýna ; Sikorová, Jitka ; Vojtíšek-Lom, M. ; Beránek, V. ; Pechout, M. ; Kléma, J. ; Cigánek, M. ; Machala, M. ; Neča, J. ; Rössner ml., Pavel ; Topinka, Jan
Motor vehicle emissions substantially contribute to air pollution worldwide and cause serious health problems. While the deleterious effects of diesel exhaust particulate matter (PM) have been widely studied, much less attention is paid to toxicity of PM emitted by gasoline engines although they also produce considerable amount of PM. The primary objective of this research was to assess toxic potencies of exhaust PM released by conventional gasoline engine fueled with neat gasoline (EU) or gasoline-ethanol blend (15% ethanol, v/v, E15). Despite a similar particle mass (mu g PM/kg fuel) produced by both fuels, PM emitted by E15 contained higher amount of harmful polycyclic aromatic hydrocarbons (PAH) as suggested by chemical analysis. To examine the toxicity of organic PM constituents, human lung BEAS-2B cells were exposed for 4h and 24h to a subtoxic dose of E0 and E15 PM organic extracts. We used genome scale transcriptomic analysis to characterize the toxic response and to identify modulated biological process and pathways. Whereas 4h exposure to both PM extracts resulted in modulation of similar genes and pathways related to lipid and steroid metabolism, activation of PPAR alpha, oxidative stress and immune response, 24h exposure was more specific for each extract, although both induced expression of PAH-metabolic enzymes, modulated metabolism of lipids or activated PPAR alpha, E15 additionally deregulated variety of other pathways. Overall, the PM mass produced by both fuels was similar, however, higher PAH content in E15 PM organic extract may have contributed to more extensive toxic response particularly after 24h exposure in BEAS-2B cells.
Photocatalytic concrete screeds with self-cleaning and antimicrobial function
Bíbová, Hana ; Šubrt, Jan ; Pližingrová, Eva ; Jakubičková, M. ; Sázavská, T. ; Dohnálek, P. ; Hykrdová, Lenka ; Jirkovský, Jaromír
Photocatalytic concrete screeds with self-cleaning and antimicrobial function have been developed and tested. These building materials contain sand grains with deposited composite TiO2/SiO2 layers. Two types of the screeds, grey and white, were prepared and their photoactivity and material characteristics were compared. Commercial TiO2 photocatalysts from several manufacturers were employed. Effects of different parameters, such as temperature of the coated sand calcination, humidity, and surface abrasion, were followed. Mechanical properties of the screeds were analyzed by SEM/XRD microscopy. Photocatalytic activity was tested by means of NOx oxidation (ISO norm 22197-1/2007). Antibacterial activity was evaluated by modified ISO norm 27447/2009 with Bacillus subtilis as a model organism.
SIZE AS AN IMPORTANT FACTOR IN NANO-TiO2 TOXICITY IN MACROPHAGE-LIKE CELLS
Líbalová, Helena ; Sikorová, Jitka ; Brzicová, Táňa ; Milcová, Alena ; Vrbová, Kristýna ; Pikal, P. ; Topinka, Jan ; Rössner ml., Pavel
A set of NPs consists of 5 variants of anatase and 5 variants of rutile nanoparticles differing in their diameter (from 3 to 165 nm). TiO2 samples were characterized in the powder form and dispersed in water and cell culture media. Three cytotoxicity assays were used: MTS, WST-1, and LDH. For all nanomaterials, three independent repetitions were carried out. \n\nOverall, cytotoxicity of all NPs was low even at the highest concentration of 256 mu g/ml. The viability of cells did not decrease below 60% for WST-1 and MTS assays and 80% for the LDH assay. Besides concentration, crystalline size was identified as the most important cytotoxic factor. Clear nonlinear relationship between crystalline size and cytotoxicity was detected, higher toxicity induced NPs within the size range 20-60 nm. Increased cytotoxicity in given diameter size range would give an answer to inconsistent findings at size and cytotoxicity relationship.
GENOTOXICITY OF NANOMATERIALS IN BEAS-2B CELLS ANALYZED BY THE IN VITRO MICRONUCLEUS ASSAY
Rössnerová, Andrea ; Červená, Tereza ; Brzicová, Táňa ; Vrbová, Kristýna ; Sikorová, Jitka ; Topinka, Jan ; Rössner ml., Pavel
The tremendous increase of the use of nanomaterials (NMs) has been witnessed during the last decade in many areas of human life including the chemical industry, cosmetics, biomedicine or food technology. The variety of NMs, their unique properties, almost ubiquitous presence and the size range of 1-100 nm raised the interest of toxicologists. The evaluation of the frequency of micronuclei (MN) as a result of the genotoxic events is a broadly utilized and well-established approach in in vitro studies for testing the risk of chemical exposure. Nevertheless, properties of the NMs give rise to the questions concerning the optimal methodological variants of the MN assay. \n\nIn our study, five types of well-characterized NMs (TiO2: NM-101 and NM-103, SiO2: NM-200, Ag: NM-300K and NM-302) of specific size, shape, or e.g. dimensions of aggregates were involved in the genotoxicity testing using four variants of protocols differing in the time of NM exposure, application of cytochalasin-B combined with simultaneous and delayed co-treatment with nanoparticles (NPs). Bronchial epithelial cells (BEAS-2B) were used in this study to fulfil these tasks. Presence of NPs was controlled by transmission electron microscopy (TEM). \n\nObtained results showed the different genotoxic potential of the various TiO2 and Ag NMs (NM-101< NM-103 and NM-300K> NM-302, respectively). Comparison of all testing strategies revealed, that the level of DNA damage can differ based on the time of exposure and the methodological approach. In general, using cytochalasin-B led most frequently to the increase of the genotoxic potential of the tested NMs.
WHOLE-GENOME EXPRESSION ANALYSIS IN THP-1 MACROPHAGE-LIKE CELLS EXPOSED TO DIVERSE NANOMATERIALS
Brzicová, Táňa ; Líbalová, Helena ; Vrbová, Kristýna ; Sikorová, Jitka ; Philimonenko, Vlada ; Kléma, J. ; Topinka, Jan ; Rössner ml., Pavel
From the perspective of the immune system, nanomaterials (NMs) represent invading agents. Macrophages are immune cells residing in all organs and tissues as the first line of defense. Interactions of macrophages with NMs can determine the fate of NMs as well as their potential toxic effects. In the present study, we compared toxicity of four different types of NMs [NM-100 (TiO2, 110 nm), NM-110 (ZnO, 20 nm), NM-200 (SiO2, 150 nm) and NM-300K (Ag, 20 nm)], towards THP-1 macrophage-like cells. Cells were incubated with non-cytotoxic concentrations (1-25 mu g/ml) of NMs for 24 hours and microarray technology was used to analyze changes in whole-genome expression. Gene expression profiling revealed a substantially different molecular response following exposure to diverse NMs. While NM-100 did not exert any significant effect on gene expression profile, all other NMs triggered a pro-inflammatory response characterized by an activation of the NF-kappa B transcription factor and induced expression of numerous chemokines and cytokines. NM-110 and NM-300K further modulated processes such as DNA damage response, oxidative and replication stress as well as cell cycle progression and proteasome function. We suppose that genotoxicity of ZnO and Ag NMs leading to DNA damage and alternatively to apoptosis in THP-1 macrophages is probably caused by the extensive intracellular dissolution of these NPs, as confirmed by TEM imaging.
GENE EXPRESSION AND IMMUNOLOGICAL RESPONSE IN MICE EXPOSED TO ZnO NANOPARTICLES
Rössner ml., Pavel ; Vrbová, Kristýna ; Strapáčová, S. ; Rössnerová, Andrea ; Ambrož, Antonín ; Brzicová, Táňa ; Líbalová, Helena ; Javorková, Eliška ; Zajícová, Alena ; Holáň, Vladimír ; Kulich, P. ; Večeřa, Zbyněk ; Mikuška, Pavel ; Coufalík, Pavel ; Křůmal, Kamil ; Čapka, Lukáš ; Dočekal, Bohumil ; Šerý, Omar ; Machala, M. ; Topinka, Jan
We analyzed gene expression changes in the lungs and the immunological response in splenocytes of mice exposed by inhalation of ZnO nanoparticles - NP. Adult female ICR mice were treated for three days and three months, respectively. Analysis of differential expression in genes involved in oxidative stress was conducted using quantitative RT-PCR. The potential immunotoxic and immunomodulatory effects of ZnO NP were analyzed by phenotyping and cytokine production by splenocytes after three months exposure. Three days exposure resulted in down-regulation of GCLC, GSR, HMOX-1, NQO-1, NF-kB2, PTGS2 and TXNRD1 mRNA expression, three months exposure increased the expression of these genes. Three months exposure caused a significant decrease in the percentage of granulocytes in the spleen cells, and affected the production of IL-10 and IL-6 by lipopolysaccharide-stimulated leukocytes. In summary, our study revealed changes in the expression of genes involved in the oxidative stress response following acute ZnO NP exposure. Subchronic ZnO NP exposure induced immunomodulatory effects in the spleen.
Introducing Functionality by Graphene Covalent Grafting
Kovaříček, Petr ; Kalbáč, Martin
Graphene is a material of great potential in a broad range of applications, for each of which specific tuning of the material’s properties is required. This can be achieved, for example, by covalent functionalization. We have exploited protocols for surface grafting by diazonium salts, by nucleophilic and electrophilic substitution to perform graphene covalent modification of graphene on substrates. The painstaking analysis problem of monolayered materials was addressed using Raman spectroscopy, SERS, SEIRA, MS, AFM, XPS and SEM/EDX. The covalent grafting was shown to tolerate the transfer process, thus allowing ex post transfer from copper to other substrates. Functional devices often require combination of several materials with specific functions, such as graphene-polymer hybrid heterostructures. We have used the developed methodology of chemical functionalization for preparation of PEDOT:Graphene bilayers by selective in situ polymerization of EDOT on covalently functionalized graphene. The polymerization proceeds exclusively on the grafted graphene, and patterned structures with high spatial resolution down to 3 μm could have been prepared. The composite exhibits enhanced efficiency of electrochemical doping compared to pristine graphene, unsymmetrical transport characteristic with very good hole-transporting properties and efficient electronic communication between the two materials. The covalent functionalization of graphene thus introduces advanced functionality to the material, broadening its scope of applications.
Photocatalytic active coatings-environmental way to improve quality and durability of buildings
Sázavská, T. ; Jakubičková, M. ; Jirkovský, Jaromír ; Šubrt, Jan ; Peterka, F.
Transparent coatings of TiO2-SiO2 nanocomposite were developed to be applied on building facades in order to prevent growth of microorganisms and thus to improve urban building sustainability. Structure and texture characteristics of the prepared nanocomposites were determined by electron microscopy (SEM, TEM + EDS), their photocatalytic activity was quantified by testing self-cleaning ability and antimicrobial activity. The self-cleaning properties were evaluated according to the standard ISO method based on photocatalytic degradation of methylene blue. The TiO2-SiO2 nanocomposite coatings were applied on various types of substrates commonly used in building industry. The antimicrobial activity was mainly investigated for algae because these microorganisms are often responsible for facades ageing. According to the laboratory tests the prepared TiO2-SiO2 nanocomposites are highly efficient. This fact was already proved by first applications in real conditions. The transparent SiO2-TiO2 nanocomposites represent an ecological and noninvasive way how to keep nice appearance of buildings for a long time. It is due to their permanent photocatalytic activity causing self-cleaning and algicidal effects. Such coatings may significantly reduce ageing processes on facades of buildings that are caused by microbiological pollution and smog exhalations.

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