This article focuses on the preparation and mechanical properties of silica/poly(vinyl chloride) (PVC) composites enriched with 60% mass ratio of 130 nm and 30 nm silica sphere fillers. Silica particles were pre-treated withsilane, IO7 T7(OH)3 (trisilanol isooctyl polyhedral-oligomeric silsesquioxane) to prevent agglomeration. The dispersion and interfacial compatibility of silica particles in a PVC matrix were investigated by scanning electron microscopy. The composite mechanical properties were characterized by tensile test, revealing improved Young modulus and tensile strength. Compared to pure PVC, the stiffness of 30 nm and 130 nm silica/PVC composites is on average increased by 30-40%, respectively. Similar trend was observed for the composite tensile strength on the change of the silica size. In contrast, elongation at break decreased for both composites compared to pure PVC, for 15% in 30 nm and for 30% in 130 nm silica/PVC composite.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 5133338With a model invertebrate animal, we have assessed the fate of magnetic nanoparticles in biologically relevant media, i.e., digestive juices. The toxic potential and the internalization of such nanoparticles by nontarget cells were also examined. The aim of this study was to provide experimental evidence on the formation of Co(2+), Fe(2+), and Fe(3+) ions from CoFe₂O₄ nanoparticles in the digestive juices of a model organism. Standard toxicological parameters were assessed. Cell membrane stability was tested with a modified method for measurement of its quality. Proton-induced X-ray emission and low energy synchrotron radiation X-ray fluorescence were used to study internalization and distribution of Co and Fe. Co(2+) ions were found to be more toxic than nanoparticles. We confirmed that Co(2+) ions accumulate in the hepatopancreas, but Fe(n+) ions or CoFe₂O₄ nanoparticles are not retained in vivo. A model biological system with a terrestrial isopod is suited to studies of the potential dissolution of ions and other products from metal-containing nanoparticles in biologically complex media.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 2768975Background: Massive industrial production of engineered nanoparticles poses questions about health risks to living beings. In order to understand the underlying mechanisms, we studied the effects of TiO2 and ZnO agglomerated engineered nanoparticles (EPs) on erythrocytes, platelet-rich plasma and on suspensions of giant unilamelar phospholipid vesicles. Results: Washed erythrocytes, platelet-rich plasma and suspensions of giant unilamelar phospholipid vesicles were incubated with samples of EPs. These samples were observed by different microscopic techniques. We found that TiO2 and ZnO EPs adhered to the membrane of washed human and canine erythrocytes. TiO2 and ZnO EPs induced coalescence of human erythrocytes. Addition of TiO2 and ZnO EPs toplatelet-rich plasma caused activation of human platelets after 24 hours and3 hours, respectively, while in canine erythrocytes, activation of platelets due to ZnO EPs occurred already after 1 hour. To assess the effect of EPs on a representative sample of giant unilamelar phospholipid vesicles, analysis of the recorded populations was improved by applying the principles of statistical physics. TiO2 EPs did not induce any notable effect on giant unilamelar phospholipid vesicles within 50 minutes of incubation, while ZnO EPs induced a decrease in the number of giant unilamelar phospholipid vesiclesthat was statistically significant (p ( 0,001) already after 20 minutes of incubation. Conclusions: These results indicate that TiO2 and ZnO EPs cause erythrocyte aggregation and could be potentially prothrombogenic, while ZnO could also cause membrane rupture.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 7420281