Titanyum Dioksit Nanopartikülleri ile Gıda Bileşenlerinin Etkileşiminin İncelenmesi

Abstract

Engineered nanoparticles have led to their use in a variety of fields, including physics, chemistry, medicine, and agriculture. Some metal nanoparticles (silver, iron, zinc) used as food additives to improve the technological properties of foods have been shown to harm human health. In this study, the interaction of TiO2 nanoparticles of different diameters (30 nm, 100 nm and 250 nm) with milk as a real food medium, which is found in high amounts in the foods consumed by children aged 1.5-6 years, was investigated. The effects of milk on nanoparticle morphology, particle surface charge, corona structure and cytotoxicity were stutied. Firstly, the behavior of the nanoparticles in the buffer simulating the ionic charge of the milk medium (whole,skim and serum) was analysed and hydrodynamic diameters for particles with diameters of 30 nm, 100 nm and 250 nm were found 2900.3 +- 411.9 nm, 3271.0 +- 131.2 nm and 2276 +- 347.7 nm, respectively. When the nanoparticles interacted with the milk, the aggregate sizes of the medium's components decreased. However, when the corona structure was examined, it was discovered that it contained a high proportion of casein proteins with SDS-PAGE. The second step of the thesis study digestion simulation applied to TiO2 nanoparticles in the food and buffer mediums and the changes in the particles were measured during digestion. The aggregate diameters of the nanoparticles in the buffer decreased from the mouth to the stomach and intestinal mediums. The diameters of the nanoparticle aggregates decreased in the milk medium, as they did before digestion. Additionally a new corona structure has been detected on nanoparticle surface in buffer medium after digestion. Furthermore, the activities of digestive enzymes that interact with the nanoparticles were measured to investigate the interaction of TiO2 nanoparticles with other components during digestion. At this point, it was determined that the nanoparticles did not reduce the activity of the amylase enzyme, caused a decrease in the activity of the pepsin enzyme only in the buffer medium, and caused a decrease in the activity of the lipase enzyme in both the buffer and milk. In the final step, the cytotoxic effects of digested TiO2 nanoparticles of various diameters on mammalian and bacterial cells were examined. The effect of nanoparticles on the viability of the Caco-2 cell was found to be dose-dependent. Additionally, while nanoparticles of three different diameters had no effect on cell viability in buffer medium, they had an adverse effect on it in food medium. According to the results of the oxidative stress precursor effect of nanoparticles, nanoparticles with a diameter of 30 nm cause significant stress on mammalian cells in the buffer, but not in the food medium. At high concentrations, nanoparticles with a diameter of 100 nm also caused the production of oxidative stress precursors in both food and buffer mediums. While the oxidative stress effect of the 250 nm diameter nanoparticle was only measured at high concentrations in buffer medium. When the effects of nanoparticles on bacterial cells were investigated, it was discovered that the effects were dose-dependent and occurred more in the buffer environment. The maximum stress effect on the bacterial cell was measured in the buffer medium with nanoparticles with a diameter of 250 nm; this effect decreased in the food medium. The differences between corona structures of buffer and food medium has affected the cytotoxicity of nanoparticles. With this study, the behavior of the TiO2 nanoparticle in the real food environment and the change of this behavior in the digestion process were investigated for the first time. Thus, detailed information was obtained about the interaction of nanoparticle with food components, digestive enzymes and different cells such as digestive epithelial cells and bacterial cells.