In current biomedically oriented research, the development of a biomimetic nanoparticle platform is of interest to provide a molecular toolbox (i.e., allowing easy modular exchange of its parts ...depending on actual needs while being nontoxic and allowing real-time recognition and tracking using various methods, such as fluorescence). We report the development of germanium(IV) oxide-polysaccharide composite particles possessing these properties. The nanoparticles are based on a crystalline germanium oxide core with a size range of 20–30 and 300–900 nm. Two new simple coating techniques were compared for the preparation of the photoluminescent polysaccharide-coated germanium(IV) oxide nanoparticles. The germanium(IV)-based core allows for in situ polysaccharide attachment via direct chelation. In addition, the nanoparticles were coated with thin layer of silicon oxide. After coating, 3-(triethoxysilyl)propyl isocyanate was grafted onto the surface, and the polysaccharides were immobilized on the particle surface via a covalent urethane linkage, which allows for an even more stable polysaccharide coating than that obtained via chelation. This approach provides access to a new material platform for biological track and image applications.
Nonlinear amphiphilic block copolymer architectures with precisely controlled structures bring new challenges to biomedical materials research. The paper describes the straightforward synthesis of ...new “snake tongue“ Y-shaped terpolymers containing poly(ethylene oxide) (PEO), poly(2-ethyl-2-oxazoline) (PEtOx) and poly(ε-caprolactone) (PCL) blocks into structure AB(C) 2 (herein referred to as MPEO 44 - b -PEtOx 252 - b -(PCL) 2×44 , MPEO 44 - b -PEtOx 252 - b -(PCL) 2×87 , MPEO 44 - b -PEtOx 252 - b -(PCL) 2×131 ). A series of well-defined Y-shaped terpolymers were successfully synthesised by a combination of living cationic and anionic ring-opening polymerization (ROP). The selected Y-shaped MPEO 44 - b -PEtOx 252 - b -(PCL) 2×44 terpolymer self-assembly was characterised in detail by static and dynamic light scattering, nanoparticle tracking analysis and cryo-transmission electron microscopy. The physico-chemical properties as well as the molecular architecture effect on the self-assembled structures and on the LCST were compared with the Y-shaped MPEO 44 - b -PEtOx 252 - b -(PCL) 2×87 and the MPEO 44 - b -PEtOx 252 - b -(PCL) 2×131 terpolymers. The results indicated a temperature-induced aggregation with an LCST between 60–63 °C for the MPEO 44 - b -PEtOx 252 - b -(PCL) 2×44 , at 60 °C for the MPEO 44 - b -PEtOx 252 - b -(PCL) 2×87 and between 45–50 °C for the MPEO 44 - b -PEtOx 252 - b -(PCL) 2×131 with significant differences in the supramolecular self-assembly behaviour compared with the analogous linear structure, clearly indicating the crucial effect of the molecular architecture. Furthermore, the increase of the molecular weight fraction of the hydrophobic block on the Y-shaped triblock terpolymers likely induced a decrease of the LCST.
Improvements in cancer diagnostics and therapy have recently attracted the interest of many different branches of science. This study presents one of the new possible approaches in the diagnostics ...and therapy of cancer by using polymeric chelates as carriers. Graft copolymers with a backbone containing 8‐hydroxyquinoline‐5‐sulfonic acid chelating groups and poly(ethylene oxide) hydrophilic grafts are synthesized and characterized. The polymers assemble and form particles after the addition of a biometal cation, such as iron or copper. The obtained nanoparticles exhibit a hydrodynamic diameter of around 25 nm and a stability of at least several hours, which are counted as essential parameters for biomedical purposes. To prove their biodegradability, a model degradation with deferoxamine is performed and, together with high radiolabeling efficiency with copper‐64, their possible use for nuclear medicine purposes is demonstrated.
A graft copolymer containing chelating 8‐hydroxyquinoline‐5‐sulfonic acid moieties on the polymer backbone and hydrophilic poly(ethylene oxide) grafts has been prepared. The copolymer forms spherical nanoparticles with internal porosity by Fe3+‐mediated self‐assembly, which can be biodegraded by metal transchelation inside cells (see picture).
This contribution describes a formulation of the optimized design of structures using the probability-based optimization method. The Monte Carlo simulation method, modified by the Latin Hypercube ...Sampling (LHS) method, was used for the calculation of the reliability of a designed structure. Efficient design procedures can achieve not only cost savings during construction (materials and energy), erection, servicing, maintenance, disassembly and material recycling but also a more favourable environmental impact. To find the best possible design for a structure an original optimization method was used. Therefore, the economical and ecological aspects (acquisition costs, CO2 and SO2 emissions and embodied energy associated with concrete member production) were taken into account in the objective function. A design example – a prestressed spun concrete pole made from reinforced concrete or alternatively from reinforced fibre concrete is presented.
Clustered regularly interspaced short palindromic repeats-associated protein (CRISPR/Cas9) system has become a revolutionary tool for gene editing. Since viral delivery systems have significant side ...effects, and naked DNA delivery is not an option, the nontoxic, non-viral delivery of CRISPR/Cas9 components would significantly improve future therapeutic delivery. In this study, we aim at characterizing nanoparticles to deliver plasmid DNA encoding for the CRISPR-Cas system in eukaryotic cells in vitro. CRISPR/Cas9 complexed polyethylenimine (PEI) magnetic nanoparticles (MNPs) were generated. We used a stable HEK293 cell line expressing the traffic light reporter (TLR-3) system to evaluate efficient homology- directed repair (HDR) and non-homologous end joining (NHEJ) events following transfection with NPs. MNPs have been synthesized by co-precipitation with the average particle size around 20 nm in diameter. The dynamic light scattering and zeta potential measurements showed that NPs exhibited narrow size distribution and sufficient colloidal stability. Genome editing events were as efficient as compared to standard lipofectamine transfection. Our approach tested non-viral delivery of CRISPR/Cas9 and DNA template to perform HDR and NHEJ in the same assay. We demonstrated that PEI-MNPs is a promising delivery system for plasmids encoding CRISPR/Cas9 and template DNA and thus can improve safety and utility of gene editing.
Herein, we present the intrinsic property of well-known polyesters poly(alkene succinates), as Candida albicans and Candida tropicalis biofilm inhibitors with potential to substantially reduce the ...incidence of device-associated infections in, e.g. , indwelling catheters and sutures. These new biopolymer applications, either for manufacturing or coating medical devices, present innovative features such as: simple and cheap preparation, easy scaling-up, good mechanical and thermal resistance properties, and antibiofilm ability without any specific surface functionalization or antimicrobial agent encapsulation. Furthermore, the polyesters are shown to be highly biocompatible, promote human mesenchymal stem cell (hMSC) attachment and proliferation, inducing morphological changes, which are dependent on the polymer structural characteristics, making them promising candidates for materials in specialized medical devices and in the tissue engineering field.
An increase in drought frequency, duration and severity is expected for the Central European region as a direct consequence of climate change. This will have profound effects on a number of key ...sectors (e.g. agriculture, forestry, energy production and tourism) and also affect water resources, biodiversity and the landscape as a whole. However, global circulation models significantly differ in their projections for Central Europe with respect to the magnitude and timing of these changes. Therefore, analysis of changes in drought characteristics during the last 54 yr in relation to prevailing climate trends might significantly enhance our understanding of present and future drought risks. This study is based on a set of drought indices, including the Standardized Precipitation Index (SPI), the Palmer Drought Severity Index (PDSI), the Palmer Z-index (Z-index) and the Standardized Precipitation−Evapotranspiration Index (SPEI), in their most advanced formulations. The time series of the drought indices were calculated for 411 climatological stations across Austria (excluding the Alps), the Czech Republic and Slovakia. Up to 45% of the evaluated stations (depending on the index) became significantly drier during the 1961−2014 period except for areas in the west and north of the studied region. In addition to identifying the regions with the most pronounced drying trends, a drying trend consistency across the station network of 3 independent national weather services was shown. The main driver behind this development was an increase in the evaporative demand of the atmosphere, driven by higher temperatures and global radiation with limited changes in precipitation totals. The observed drying trends were most pronounced during the April−September period and in lower elevations. Conversely, the majority of stations above 1000 m exhibited a significant wetting trend for both the summer and winter (October−March) half-years.
Expected impacts of climate change on forests: Czech Republic as a case study Hlasny, T.,Narodne Lesnicke Centrum, Zvolen (Slovak Republic). Lesnicky Vyskumny Ustav; Holusa, J.,Ceska Zemedelska Univ., Prague (Czech Republic). Fakulta Lesnicka a Drevarska; Stepanek, P.,Cesky Hydrometeorologicky Ustav, Brno (Czech Republic) ...
Journal of Forest Science,
(Oct 2011), Volume:
57, Issue:
10
Journal Article
Peer reviewed
Open access
We provide fundamental information about the future development of selected climate elements in relation to anticipated threat to forests in the Czech Republic. All analyses were carried out in ...relation to four elevation zones with specific potential forest vegetation - up to 350 m a.s.l. (oak dominance), 350-600 m a.s.l. (beech dominance), 600-900 m a.s.l. (beech-fir dominance), 900-1,100 m a.s.l. (spruce dominance). We found out that while the projected increase in mean annual air temperature is almost constant over the Czech Republic (+3.25-3.5 deg C in the distant future), the frequency of heat spells at lower elevations is expected to increase dramatically compared to higher elevations. The precipitation totals during the vegetation season are projected to increase in the near future by up to 10% and to decrease in the distant future by up to 10% over all vegetation zones. In general, drought is presumed to become a key limiting factor at lower elevations, while increased temperature along with the prolonged vegetation season at higher elevations can be beneficial to forest vegetation. Consequently, northward progression of forest tree species and retraction of the species lower distribution range are a generic response pattern. Such impacts are presumed to be accompanied by changes in the distribution and population dynamics of pests and pathogens. Mainly the impacts on two key forest pests, Ips typographus and Lymantria dispar, are discussed.
The present study is focused on the potential occurrence of the Colorado potato beetle (Leptinotarsa decemlineata, Say 1824), an important potato pest, and the European corn borer (Ostrinia ...nubilalis, Hübner 1796), the most important maize pest, during climate change. Estimates of the current potential distribution of both pest species as well as their distribution in the expected climate conditions are based on the CLIMEX model. The study covers central Europe, including Austria, the Czech Republic, Hungary, and parts of Germany, Poland, Romania, Slovakia, Switzerland, Ukraine, Slovenia, the northern parts of Serbia, parts of Croatia and northern Italy. The validated model of the pests’ geographical distribution was applied within the domain of the regional climate model (RCM) ALADIN, at a resolution of 10 km. The weather series that was the input for the CLIMEX model was prepared by a weather generator (WG) which was calibrated with the RCM-simulated weather series (for the period of 1961–90). To generate a weather series for two future time periods (2021–50 and 2071–2100), the WG parameters were modified according to 12 climate change scenarios produced by the pattern scaling method. The standardized scenarios derived from three global climate models (HadCM, NCAR-PCM and ECHAM) were scaled by low, middle and high values of global temperature change estimated by the Model for the Assessment of Greenhouse-gas Induced Climate Change (MAGICC) model (assuming three combinations of climatic sensitivity and emission scenarios). The results of present study suggest the likely widening of the pests’ habitats and an increase in the number of generations per year. According to the HadCM-high scenario, the area of arable land affected by a third generation per season of Colorado potato beetle in 2050 is c. 45% higher, and by a second generation of the European corn borer is nearly 61% higher, compared to present levels.
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