Jasna Lojk owas awarded Krka award for 2015 for her PhD thesis (mentor Mojca Pavlin, MR mentor VB Bregar) The young researched Jasna Lojk graduated under the supervision of assist. prof. dr. Mojca Pavlin with the doctoral dissertation titled Analysis of interactions between cells and magnetic nanoparticles. The scope of the thesis research was to evaluate previously developed polyacrylic acid (PAA) coated cobalt ferrite nanoparticles (NPs) as potential NPs for biotechnological applications. By using several different microscopic and spectroscopic techniques we analysed NP interactions with the cell membrane, internalization pathways, intracellular trafficking and intracellular fate of NPs. We showed that NPs enter the cell in high quantities and accumulate in perinuclear regions of the cells. To quantify the uptake, we tested several different techniques (microscopy, spectroscopy) and implemented and optimized a technique of our own. Analysis of mechanisms of NP toxicity showed that PAA coated NPs are relatively non-toxic even at high concentrations, do not cause formation of reactive oxygen species, activation of transcription factor NF-κB or induce apoptosis. The results showed that PAA coated cobalt ferrite NPs are relatively nontoxic and accumulate in the cells in high quantities. Based on these findings, the NPs would be suitable for biotechnological application like cell labelling and tracking.
E.01 National awards
COBISS.SI-ID: 11039572Cationic additives in nanoparticles, such as polyethyleneimine (PEI), can trigger cell death and toxic responses [1]. PEI induced toxicity is still the major obstacle in its use [2]. The aim of our study was to develop a simple method for reducing toxicity of Cobalt ferrite-polyacrylic acid (PAA) - PEI multilayer nanoparticles (NPs) by additional binding of glutathione (GSH). Possible mechanisms of toxicity reduction are the anti-oxidative effect of GSH by ROS scavenging processes and reduced membrane damage, due to lower surface charge of PEI. Cobalt ferrite-PAA-PEI-FSC (fluorescein modified NPs) were used as a modification control without anti-oxidative properties. All experiments were performed on Chinese hamster ovary (CHO) cell line. We have shown reduced toxicity with propidium iodide viability assay, MTS viability assay, ROS measurements and total intracellular glutathione determination. TEM micrographs showed that internalization was achieved with or without modification and transfection with GFP followed by fluorescence microscopy showed equal efficiency at higher viability using GSH formulation.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 10990164Numerous different types of nanoparticles (NPs) are being designed with properties suitable for various NP applications; however, their toxicity is usually the limiting factor of their applicability. Several different mechanisms of NP toxicity are known, from genotoxicity and oxidative stress, to activation of the immune system and induction of cell death. NP toxicity can not only damage the cells and tissues, but also impair the function of NPs and the efficacy of the application. Thorough understanding of the mechanisms is essential for further design and improvement of NP formulations. In this study, we looked into the mechanisms of toxicity of two types of cobalt ferrite NPs, coated with either negatively charged polyacrylic acid (PAA) or positively charged polyethylenimine (PEI). B16 cell line and primary human myoblasts (MYO) were exposed to increasing concentrations of NPs and cell viability was performed. To determine the mechanisms of observed decrease in viability, we determined the generation of reactive oxygen species, activation of the transcription factor NF-κB and determined the mechanisms of cell death. While PAA coated NPs were generally non-toxic, PEI NPs induced cell death, mainly through necrosis.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 10989908