Third Science Rendezvous presenting research conducted at UCT Prague took place online on Tuesday 3 November 2020. Talks were held by research fellows whose work is supported by ChemFells and ChemJets mobility projects.
|Paula Da Silva Tourinho||Microplastic fibers as a vector of silver nanoparticles: adsorption mechanisms and ecotoxicity|
|Gabriela Ruphuy Chan||Yeast-derived Particles for Drug Delivery|
|Aiym Tleuova||Temperature-responsive safer formulation of fungicide|
|Magdalena Urbaniak||Plant secondary metabolites and microbial degradation of structurally related xenobiotics|
|Alexandr Zubov||Discrete Element Modelling of Colloidal Suspensions|
|Prasad Talluri||High-performance Membranes for Separation of Biofuels|
|Martin Janda||Bacterial extracellular vesicles and their functions in plants|
|Eva Muchová||Theoretical modelling of X-ray processes: Probe of aqueous structure|
Paula Da Silva Tourinho
Plastic pollution is far and wide. All environments, from urban areas to the most isolated places, are contaminated by small plastic fragments known as microplastics. One main type of microplastic is the synthetic fibers released from textiles. These microplastic fibers are released from the washing machines in our home, reaching aquatic and terrestrial habitats. Once in the environment, microplastic fibers can adsorb other chemical pollutants, acting as a carrier for these pollutants. We aimed at investigating the adsorption of silver nanoparticles to polyester microplastic fibers and its toxic effects on aquatic and terrestrial organisms. Silver nanoparticles were chosen as the model pollutant for being vastly used in the textile industry due to its antimicrobial properties.
Gabriela Ruphuy Chan
Yeast is one of the most commonly used ingredients in the food industry, but less commonly known is its potential use in drug delivery. The so-called yeast-derived beta glucan particles (GPs) are obtained from the cell wall of Saccharomyces cerevisiae (baker’s yeast), and because they are hollow and porous microparticles, they are suitable candidates as drug carriers. The mechanisms in which yeast glucan particles can potentially improve oral bioavailability of drugs will be briefly explained and discussed.
Temperature-responsive safer formulation of fungicide
To date fungicides are irreplaceable tool for combatting phytopathogenic fungi and for keeping high efficacy of agriculture. However, most of fungicides have several disadvantages, such as low water solubility, degradation under environmental impact, ecotoxicity, necessity of big amounts and repeated spraying. To solve these issues microencapsulation technique can be implemented. This allows to control and target the release, to eliminate active ingredient (AI) from aggressive environment, improve properties of AI, protect environment against toxicity of AI, etc. In this work fungicide pyraclostrobin was encapsulated to control its release via temperature change. In order to employ such temperature-responsive ability to fungicide formulation a phase change material (octadecane) was used as a core of microcapsule. Pyraclostrobin-loaded microcapsules were characterized using SEM, DLS, FTIR techniques, stimuli-responsivity was tested by means of in vitro tests with pathogenic culture (Fungal strain of Pyrenophora teres - CPPF-453) grown in Petri dishes. PyrMCs showed excellent antifungal effect above the melting point of octadecane (~28°C) and weaker effect below 28°C. Research results demonstrate a potential of temperature-responsive microencapsulated fungicide for successful utilization in agriculture.
Rhizoremediation is one of the most effective processes of pollutants removal due to existing interactions in the rhizosphere between plant exudates, including plant secondary metabolites (PSMs), and microorganisms.
Although there is a considerable body of evidence that PSMs can cause changes in microbial community composition and stimulate microbial degradation of xenobiotics, the mechanisms of action on the molecular level (e.g. degradative gene induction) in relation to their chemical structure have not been fully understood yet. With this in mind, our aim is to acquire new knowledge on the role of PSMs in the microbial degradation of structurally related xenobiotics and in the expression level of the corresponding degradative genes.
Discrete Element Method (DEM) is a popular method for modelling dynamics of granular media and powders materials. In this contribution we demonstrate how DEM can be utilized for prediction of complex phenomena arising in colloidal suspensions, e.g. particle coagulation, fouling, as well as estimation of suspension properties like viscosity and viscoelasticity.
The transient and steady pervaporation of 1-butanol–water mixtures through a poly[1-(trimethylsilyl)-1-propyne] (PTMSP) membrane was studied to observe and elucidate the diffusion phenomena in this high-performing organophilic glassy polymer. Pervaporation was studied in a continuous sequence of experiments under conditions appropriate for the separation of bio-butanol from fermentation broths: feed concentrations of 1.5, 3.0 and 4.5 w/w % of 1-butanol in nutrient-containing (yeast extract) water, temperatures of 37, 50 and 63 °C, and a time period of 80 days. In addition, concentration polarization was assessed. As expected, the total flux and individual component permeabilities declined discernibly over the study period, while the separation factor (average β = 82) and selectivity towards 1-butanol (average α = 2.6) remained practically independent of the process conditions tested. Based on measurements of pervaporation transients, for which a new apparatus and model were developed, we found that the diffusivity of 1-butanol in PTMSP decreased over time due to aging and was comparable to that observed using microgravimetry in pure vapor in 1-butanol. Hence, despite the gradual loss of free volume of the aging polymer, the PTMSP membrane showed high and practically independent selectivity towards 1-butanol. Additionally, a new technique for the measurement and evaluation of pervaporation transients using Fourier transform infrared spectroscopy (FTIR) analysis of permeate was proposed and validated.
Vesiculation is a process of Gram-negative bacteria to release extracellular vesicles (EVs) into the environment. Bacterial EVs contain molecular cargo from the donor bacterium and play important roles in bacterial virulence and survival. In my project we were focused on the EV production by plant‑pathogenic Pseudomonas syringae pv. tomato DC3000 (Pto DC3000), the causal agent of bacterial speck disease. we demonstrated that Pto DC3000 produce EVs in planta. We characterized Pto DC3000 EV proteome. The potential contribution to Pto DC3000 plant infection of EV proteins was assessed using other in planta *omics data sets and plant treatments. These results point at roles for EVs in bacterial defenses and nutrient acquisition of Pto DC3000.
In X-ray photochemistry we focus on modelling processes that are induced by high energy radiation. This field has witnessed unprecedented importance because of novel experiments at synchrotrons of free electron lasers facilities. The possible applications range from radiation therapy to control of chemical reactivity.
Due to its novelty, theoretical modelling lags behind experiments. We assemble and modify theoretical tools to help us understand processes in which molecules in solutions deactivates after being irradiated by X-rays. We investigate if these relaxation processes can be a basis of novel Auger-type X-ray spectroscopies which would allow us to study the “chemical environment” in solutions.