Plants are sources of broad spectrum of compounds potentially useable as antioxidants and UV protectants in cosmetics. This work aims at extraction and preservation of chosen plant extracts into combined PHA/phospholipid nanoparticles in order to prolong their activity and stability. Extracts were characterized in terms of polyphenols, flavonoids, antioxidant activity, UV protective properties and packed into liposomes.
Encapsulation efficiency of PHA/liposomes was characterized by spectrophotometry. Particle size and size distribution were observed by dynamic light scattering and colloid stability by determining zeta-potential. Safety of prepared particles with plant extracts were tested by MTT and LDH assay on human keratinocytes. Influence of functionalized particles on cell viability was evaluated. Genotoxicity was tested using SOS Chromotest.
All of the prepared samples showed moderate or high encapsulation efficiency (40 - 97 %). Extracted active compounds had high antioxidant activity as well as UV protective effect. The most of prepared particles did not posses cytotoxic effect on human keratinocytes. No genotoxicity was found in tested particles.
Encapsulation of active compounds from plants into combined PHA/lipomes can be an interesting way how to prolog their activity. Besides UV protecting effect for natural cosmetics they can find use as preservants in cosmetics as well as in food industry.
ACKNOWLEDGEMENTS: This work was also supported by the project “Materials Research Centre at FCH BUT—Sustainability and Development” no. LO1211 of the Ministry of Education, Youth and Sports of the Czech Republic.
Nanotechnologies represent new promising approach for conservation and preservation of cultural heritage. Nanomaterials have been shown to improve efficacy, durability and quality of the restoration due to their unique properties that can be achieved and tuned by controlling particle physico-chemical characteristics. The same characteristics, however, affect the way how nanomaterials interact with biological systems and may potentially underlie their enhanced or unexpected toxicity. In this pilot study, we compared the toxic potential of representatives of three of the most common oxide materials applicable in restoration: TiO2 (standard and purified P25, a mixture of prevailing anatase with rutile crystalline modifications), SiO2 (bare A200, and R805, R9200 as coated forms of A200), and ZnO. Using two in vitro cytotoxicity assays, WST-1 and LDH, evaluating metabolic activity and cell membrane integrity, respectively, we preliminary ranked the tested substances according to their cytotoxic potential, which may be used for their prioritization for further testing and applications. After 24h exposure, a dose-dependent decrease in cell viability was only detected in ZnO nanoparticles and uncoated silica A200). Hydrophobic coated silicas (R805 and R9200) and TiO2 nanoparticles (purified and unpurified P25) did not exhibit cytotoxic effects up to the highest tested concentration of 250 μg/mL. Toxicological data related to the physico-chemical characteristics will be applicable in developing both more efficient and safer nano-based products for restoration and conservation. ACKNOWLEDGEMENTS: Supported by the Ministry of Education, Youth and Sports #LO1508.
Micronucleus assay, which has been used for almost sixty years, is one of the basic methodological approaches of genetic toxicology. This is also evident from more than 10,500 references found in PubMed database. These studies concern the evaluation of cytotoxicity and genotoxicity of numerous chemicals and in the last decade also nanomaterials (NM) and nanoparticles (NP). Surprisingly, no relevant human studies focused on MN formation following the exposure to NP have been reported.
In our study we analyzed 4x (in September 2016 and 2017; pre-shift and post-shift each year) a group of persons, long-term (years) working in nanocomposites research, and matched controls. Detail aerosol exposure monitoring of particulate matter (PM) including nano-sized fractions was completed during working shift in a sampling day. The micronucleus assay using Pan-Centromeric Chromosome Paint was applied to recognize, beside the frequency of total micronuclei (MN) in binucleated cells (BNC), also other types of chromosomal damage (losses and breaks), including the centromere positive (CEN+) and centromere negative (CEN-) micronuclei.
The monitoring data showed differences in the risk of exposure to NP related to individual working processes, as well as differences in chemical composition of nano-fraction. Cytogenetic results demonstrated consistently (both years): (i) possible adaptation to long-term exposure of NP (related to total frequency of MN), (ii) short-term (daily) exposure could be a reason for the aberration increase, particularly a chromosomal losses (aneugenic effect).
ACKNOWLEDGEMENTS: Supported by the Grant Agency of the Czech Republic #18-02079S and the Ministry of Education Youth and Sports Czech Republic #LO1508.
Copper oxide nanoparticles (CuO NPs) are used in numerous applications including antimicrobial agents, semiconductors, chemical sensors, catalysts and others. However, their high toxic potential and growing industrial production increase the concern for health and environmental risks.
The present study aimed to investigate the toxicity of pristine versus surface-modified CuO NPs in relation to their stability/dissolution in cell culture medium, cellular uptake, cytotoxicity and ROS production in mouse macrophages RAW264.7. Our results showed that NPs modified with different coating agents [citrate (CIT), ascorbate (ASC), polyethyleneimine (PEI) and polyvinylpyrollidone (PVP)] affected the dissolution of the NPs in water but not in cell culture medium. Further, in vitro testing demonstrated that PEI-coated NPs were most cytotoxic while ASC-coated material exerted the lowest cytotoxicity. The anionic coatings CIT and ASC also provided protection against CuO NPs-induced oxidative stress and decreased levels of ROS production. Cellular internalization assessed by TEM was detected in cells exposed to CIT, ASC, PVP-coated and pristine NPs but not PEI-CuO NPs. Intracellular Cu content in cells tended to decrease with time, resulting in reduced cell/total Cu ratios, with the highest reduction noted for cells exposed to uncoated NPs. Overall, the toxicity of the surface-modified CuO NPs could be explained by synergistic interactions between the NPs, their dissolution, and the toxicity of the coating agents.
ACKNOWLEDGEMENTS: This work was supported by the Seventh Framework Programme (604305) and the COST Action MODENA (TD1204), and by the Czech Science Foundation (P503/12/G147), and the Ministry of Education, Youth and Sport of the Czech Republic (LO1508).
Carbon dots (CDs) as the new fluorescent material with low toxicity and excellent optical properties show great promise in various fields of biomedicine, especially bioimaging. In this study, we used two types of carbon dots similar in size (<10 nm) but with different surface charge. The first carbon dots were synthesized by thermal oxidation of Tris and betaine and resulted into carbon dots with quaternary ammonium (QCDs) and strong positive charge (+43 mV).1 Synthesis of the second carbon dots contained solvothermal decomposition of urea and citric acid dissolved in formamide. After this step the prepared mixture was separated on a preparative anion-exchange column to obtain carbon dots exhibiting red fluorescence (rCDs) with negative surface charge (-29 mV).2 Because toxicity plays the key role in potential biomedical applications, both CDs were subjected to series of toxicity tests on normal (HEL 12469) and tumor (A549) lung cell lines: viability evaluated by WST-1 assay and flow cytometry, detection of reactive oxygen species (ROS) by CM-H2DCFDA probe and intracellular distribution by transmission electron microscopy. While rCDs showed no decrease in viability of either cell line even at the highest tested concentration of 500 µg/ml after 24h incubation, QCDs caused significant decrease in cell viability at this concentration and dose-dependent increase in ROS levels. Higher cytotoxicity of QCDs may be related to their positive surface charge probably damaging cells via a proton-sponge effect. Overall, both materials showed excellent biocompatibility up to 100 µg/ml and unique fluorescence properties which makes them promising for use in bioimaging.
REFERENCES: [1] Bourlinos, A. B.; Zbořil, R.; Petr, J.; Bakandritsos, A.; Krysmann, M.; Giannelis, E. P., Luminescent Surface Quaternized Carbon Dots. Chemistry of Materials 2012, 24 (1), 6-8.; [2] Holá, K.; Sudolská, M.; Kalytchuk, S.; Nachtigallová, D.; Rogach, A. L.; Otyepka, M.; Zbořil, R., Graphitic Nitrogen Triggers Red Fluorescence in Carbon Dots. ACS Nano 2017, 11 (12), 12402-12410.
Hydrophilic graphene derivatives are promising candidates in biological and medical applications. However, it is necessary to evaluate their risks and mechanisms underlying their potential toxicity. Autophagy is a cellular pathway that could represent such a cytotoxic mechanism. Therefore, this study examined the autophagic response of HeLa cells to treatment with graphene oxide and graphene acid. The former is well-established graphene derivative which has been successfully used in biological applications while the latter represents a novel hydrophilic graphene derivative developed in our institute. (A. Bakandritsos, et al. ACS Nano 11 (3), 2982-2991 (2017)) To monitor autophagy, the levels of protein markers LC3B and SQSTM1/p62 upon exposure to graphene oxide and graphene acid were analysed by western blot. Moreover, autophagic vesicles were detected and quantified in live cells by flow cytometry using specific fluorescent staining. At various concentrations studied, graphene oxide altered the steady-state level of both protein markers while graphene acid had almost no impact. These findings were also supported by flow cytometry analysis that showed increased amount of autophagic vesicles in graphene oxide-treated cells while cells treated with graphene acid were comparable to those of control. In conclusion, graphene acid can be considered as safer nanomaterial than graphene oxide in terms of autophagy induction.
Graphene acid (GA) is a novel graphene-based material that has many extraordinary properties including excellent colloidal stability, biocompatibility, and high conductivity.1 The last few years have witnessed rapid development of biological and medical applications of graphene-based materials such as drug delivery, biosensing, and bioimaging. However, cellular uptake mechanism and pathway of GA is not fully known.
In this work, Raman spectroscopy is employed to studied the cellular uptake pathways of GA by cancer (HeLa) and non-cancerous cell lines (HEL). Using Raman imaging, we were able to track the GA cellular uptake pathways in cells without any additional fluorescent labels.
ACKNOWLEDGEMENTS: The authors gratefully acknowledge support from project NPU LO1305 of the Ministry of Education, Youth and Sports of the Czech Republic.
REFERENCE: [1] Bakandritsos, A.; Pykal, M.; Błoński, P.; Jakubec, P.; Chronopoulos, D. D.; Poláková, K.; Georgakilas, V.; Čépe, K.; Tomanec, O.; Ranc, V.; et al. Cyanographene and Graphene Acid: Emerging Derivatives Enabling High-Yield and Selective Functionalization of Graphene. ACS Nano 2017, 11 (3), 2982-2991.
The paper deals with the analysis and experiment on the spinning device for the production of nanofibers by electrostatic spinning from strings. The work follows the research carried out in the studies [4, 5], where the intensity of the electric field and the distance of the Taylor cones were monitored, respectively. nozzles from which emerging nanofibers travel to the collector, depending on the different cross sections of the strings used. The aim of the present study was to analyze the influence of the magnitude of the applied voltage on the electrode and the collector on the intensity of the electric field during the spinning, and to analyze the effect of the string geometry with the constant thickness of the polymer layer on the spinning process.
The paper contains analysis of the results of nanoparticle measurements in technological plants (machine plants, building materials production, automotive repair and transport, brewery, processing of sandstone, etc.). The measurements identified the main sources of nanoparticles, their distribution in the working environment, including the influence of the measurement results by physico-chemical factors.
The aim of the measurement is to find a systemic measure in cooperation with the employer (in the sense of a certified methodology for the provision of personal protective equipment in nanoparticle environment, VÚBP v.v.i., Prague 2016) to reduce the impact of nanoparticles on employees by technological measures and using protective working equipment.
A firearm shot is a complicated physico-chemical process in where the by-product of the shot is a shot-fire product that contains both metallic and non-metallic nano and microparticles.
The experiments were focused on measuring their concentration (range 20-1000 nm) after gun shots which is the most used weapon during training shooting on the shooting range. Particles penetration was detected by the various types of respirators. The efficiency was calculated from the measured values especially their fit factor. The samples from the shot fills were further tested on their phytotoxicity - a component of environmental toxicity. Finally the paper discusses the environmental impact of the shooting range.
Montmorillonite is a one of the most important groups of phyllosilicates and is an excellent sorbent. For the facilitation of the post-sorption sorbent separation from the medium (e.g.) waste water, it is convenient to use its magnetically modified form. Magnetically modified montmorillonite composites can be prepared using a simple microwave synthesis, the efficiency of this preparation method has already been proven. The aim of this study was to evaluate the effect of the microwave radiation during the preparation of its magnetic form on the structure and stability of montmorillonite. Water extracts were prepared by batch method using deionized water. The leachate was prepared for 24 hours in different ratios of solid and liquid phase (1:10 000, 1:1 000, 1:500 a 1:100) from the montmorillonite and the magnetically modified montmorillonite. Concentrations of Al, Ca, K, Mg, Na, Si, Ti and Fe were determined using atomic emission spectrometry with inductively coupled plasma, pH of the filtrate was also determined. The results of the experiments showed that Al and Ti do not leach under the observed conditions. The assumption that the ion exchange elements (K, Na, Ca, Mg) leach to the solution was confirmed. Their amount is dependent on the leaching time and on the solid/liquid phase ratio. Silicon, a part of the fundamental layer structure also leached, however, in an amount not affecting the montmorillonite structure. The process of the microwave-assisted magnetic modification of the montmorillonite was proved not to affect the stability of the material.
Imazaquin is a chiral compound that can exist as two enantiomers: R-imazaquin and S-imazaquin. It is known that the herbicidal activity of imazaquin is due to the R-enantiomer mainly. This herbicide is characterized by a high mobility in alkaline soils, which may cause groundwater and surface water pollution. So, in order to avoid the addition of the less active S-enantiomer and reduce the great mobility of imazaquin, a clay-based nanoformulation of imazaquin containing exclusively the biologically active enantiomer was prepared. After evaluating several clay materials, cetyltrimethylammonium-saturated montmorillonite was selected as a carrier of the herbicide, due to its high loading capacity and great stability of the resulting nanoformulation. Next, the benefits of applying this nanoformulation compared to the use of the free (water dissolved) racemic herbicide or the free pure R-imazaquin enantiomer were assessed based on the leaching behavior and bioefficacy of the herbicide under a simulated intensive rain event. The results showed that the leaching of imazaquin was slower when the herbicide was added as nanoformulation in comparison with the free herbicide in the form of racemic mixture or pure R enantiomer. This was attributed to the sustained release of imazaquin from the nanoformulation, which reduced the amount of herbicide available for leaching. In a simulated scenario of a high water input shortly after herbicide application, the bioassay experiments showed that reduction of imazaquin losses as a consequence of the use of the nanoformulation led to a higher herbicidal efficacy than those for free racemic mixture and free R-imazaquin.
Nanopesticides represent an emerging technological development that aims to improve the efficacy of existing pesticide active ingredients and/or to enhance their environmental safety profiles. Nanopesticides encompasses a great variety of formulation types e.g. nanoemulsions, polymer-based, and inorganic. Nanoformulations are expect to have significant impacts on the environmental fate of active ingredient (a.i.). Sorption is one of the major processes that determine the fate, effects, efficacy and ecological risks of pesticides in terrestrial and aquatic environments process. The aim of this study was to evaluate the extent to which different formulations may affect the fate of difenoconazole in soil. Soil sorption of difenoconazole was measured for i) pure active ingredient, ii) commercially available formulation (particle size of 174 ± 7 nm), iii) formulation with polymer (565 ± 27nm), iv) formulation with conventional polymer (959 ± 55 nm). Standard batch equilibrium method (OECD no. 106, 2000) was applied to determine the fate properties of formulations in three agricultural soils. The experiment showed that there were differences upon comparison of the results obtained for the polymer (565 ± 27nm) and commercial formulation with that of the pure a.i. Pesticide formulation with polymer (565 ± 27nm) and commercial formulation yielded smaller soil distribution coefficients (Kd values) in all three soils relative to that of the pure a.i. Laboratory experiments showed that the nanoformulation could increase the measured sorption coefficients.
Interaction between engineered nanoparticles and plants is still a widely unexplored area. While there is a growing body of research on the toxicity of nanoparticles to plants, their stress-inducing capabilities are less known. Determination of chlorophyll content in plant leaves is a relatively easy way of real-time assessment of the physiological state of the plant. Cauliflower (Brassica oleracea convar. Botrytis) seedlings were subjected to the TiO2 nanoparticles either by being planted in the nano-TiO2 enriched soil (1g/kg) or by exposure of its leaves to nano-TiO2 suspension (1g/L). Chlorophyll content in the shoots (mmol/m2) was measured both before and following the exposure in set interval, shoots were then harvested and prepared for Ti content analysis. While no significant decrease of chlorophyll content was observed in the unexposed plants, chlorophyll content significantly decreased after four days in the seedlings growing in the nanoparticle-enriched soil and after twelve days in the seedlings subjected to the suspension. All the seedlings appeared vital, yet the decrease in chlorophyll content indicates nanoparticle-induced stress that may seriously affect the yield from cultivated crops when these are exposed to nano-metal oxides or their composites as well as raise health concerns due to their bioaccumulation in the plant tissues.