Guest researcher abroad

  • February 2013 3 weeks

    Plasma for biomedical applications

    Rresearcher at Department of Electrical Engineering and Computer Science Hori Sekine,laboratory at Nagoya University, Japan., I was studying lung and breast cancer cells regarding their response using plasma liquid discharges.

  • September 2012 2 weeks

    Plasma for biomedical applications

    researcher at Paul Sabatier University Toulouse III ∙ Laboratoire Plasma et Conversion d'Energie LAPLACE, France., My research was focused on treatment of stents and their cover made of dust particles created with low pressure magnetized plasma.

  • January 2010 2 weeks

    Neuroscreen project EP6

    Researcher at CHU Lyon, Diagnostic Maladies à prions, France., My work was focused on evaluation of new diagnostic method covered by EU project Neuroscreen.

  • March 2009 2 weeks

    Neuroscreen project EP6

    Researcher at Université de Liège, Belgium., I was using ELISA tests to evaluate improvement on our functionalized magnetic beats

  • 2006 2005

    IAESTE trainee

    Trainee in laboratory for analytical chemistry, Clariant SE, Switzerland., (1 year) I was responsible for development of new analytical methods for specialized Copolymer products.

Education

  • Ph.D. 2012

    Ph.D. in Physics

    Jožef Stefan International Postgraduate School

  • B.A.2006

    Bachelor of Chemistry

    Faculty of Chemistry and Chemical Technology, Ljubljana

Honors, Awards and Grants

  • 2011
    Grant from Slovenian Research Agency (ARRS) for research and development activities at Tomas Bata University in Zlin, CZ (4 months).
  • 2009
    Best poster award.

    Emerging field of BIO-NANOTECHNOLOGIES, 1st International Plasma Nano-science Symposium.

  • 2009
    Certificate from European Patent Academy Seminar AU112009
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Laboratory

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Image of SIMS and XPS at the department F4.

Plasma laboratory.

Research Projects

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    Research on synthesis of nano wires and their application in regenerative energy cells

    2011-2014

    Metal oxide nanowire arrays on metal substrates are interesting for various electrochemical and photoelectrochemical applications in energy conversion. Additionally, the lack of oxygen atoms in nanostructures of metal oxides can be used for tailoring electronic properties of the structure in order to modify adsorption of light quanta and to transfer the charge through the nanowire. In this view, plasma oxidation of metal foils provides a unique possibility for large scale vertical growth of nanowire arrays on metal surfaces as well as synthesis of nanostructures with oxygen vacancies, which can be achieved by changing plasma parameters in a controlled manner. The project is focused on plasma synthesis of various metal oxides nanowires (predominantly Fe2O3, Cr2O3, CuO2, MoO3 in V2O5) and testing their properties in regenerative energy cell applications, like dye-sensitized solar cells or cells for photoelectrochemical splitting of water molecules In more detail, the main focus of the research will be based on synthesis of new metal oxide nanowire arrays in low-temperature oxygen plasma under controlled plasma parameters and their applications in photoelectrochemical cells. With this aim, we will extensively study the role of plasma parameters (e.g. density of electrons, neutral atoms, excited molecules and photons) on the nanowire synthesis from metal substrates such as chrome, iron, copper and vanadium. In addition, we will grow nano systems also on flexible surfaces with plasma vapour deposition or from thin metal films. The modifications of surface morphology and characteristics of nanostructures, synthesised under different plasma conditions, will be studied as well. We will try to find the deterministic rules for nanowire growth in oxygen plasma. Synthesised metal oxides nanostructures (like Fe2O3, Cr2O3, CuO2 in V2O5) will be used in the regenerative energy cells. The structures will be used as electrodes for photoelectrochemical cells which adsorb sun light and enable splitting of water molecules and thus production of fuel gases (oxygen and hydrogen) as well as for dye-sensitized solar cells. The research will be followed by development of new electrochemical cells for energy conversion, which are based on metal oxide nanowire arrays on metal substrates that were synthesised in oxygen plasma. In addition, it is worth mentioning that our Slovenian industrial partners are interested in development of these devices.

    HEAD: Uroš Cvelbar

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    Toward ecologically benign alternative for cleaning of delicate biomedical instruments

    Applied research project. 2011-2014

    Interdisciplinary research on removal of selected organic materials from the surface of surgical devices by non-equilibrium gaseous treatment will be performed. Experiments will be performed in three types of non-equilibrium oxygen gas found in weakly ionized plasma in glow discharge, early afterglow and late afterglow. The organic materials will be a simple polymer, three different proteins, and bovine blood. Extensive experimental as well as theoretical work on interaction of different reactive particles will allow for determination of the removal rates under different conditions, as well as quantification of the results in terms of reaction probabilities. The original approach will allow for preparation of a database on interaction probabilities that will represent an important tool for broad community of researchers worldwide working on interaction between reactive gaseous plasma and organic materials. Furthermore, interaction between reactive particles and surgical devices will be studied in order to determine critical parameters that are tolerated for future dissemination of results in terms of application in surgical practice. Advanced methods for creation of non-equilibrium gases with adjustable concentration of reactive particles will be applied and characterized by specially adopted catalytic probes as well as optical techniques. Thickness of organic films will be monitored by quartz crystal microbalance (QCM) while the surface properties will be monitored using X-ray photoelectron spectroscopy (XPS), secondary ion-mass spectrometry (SIMS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results will allow for preparation of a patent application as well as several scientific papers suitable for publication in top quality journals. Systematic experimental as well as theoretical work will demonstrate the applicability of this technique (that fits best to physical chemistry) in medical practice. Industrial partner will gain appropriate knowledge that may allow for future dissemination of the results.

    A detailed review of the literature shows that there is very little known about the interaction of plasma particles with the proteins. The results that will be obtained within the proposed project will allow for calculation of the etching rate and reaction probability as a function of the samples temperature and the type of material (protein) being treated. The final result will be a database that will allow for very accurate determination of plasma parameters that are needed for effective etching (removal) of organic impurities (proteins) from the surface of treated materials. Treatment of model samples with only one type of particles (neutral oxygen atoms, metastable molecules / atoms or ions) or with a combination of all of them will allow for a detailed explanation of the role that each particle plays in the interaction with the proteins. The precise and accurate choice of plasma parameters is essential for selectively removal of protein impurities from the surface of surgical instruments without damaging their surface.

    HEAD: Alenak Vesel

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    Investigation of gaseous discharges for introduction of a new environmentally friendly technology for semimanufactures functionalization at capacitors production

    Applied research project. 2008-2011

    Characteristics of gaseous discharges suitable for application in large vaccum chambers such as the chamber for metallization of polymer foils will be investigated. The goal of the project is an optimization of the technology for production of foil capacitors and thus higher quality of the products. The stability of plasma sustained by such discharges will be monitored with Langmuir and catalytic probes, as well as by optical emission spectroscopy, Two-photon Absorption Laser Induced Fluorescence (TALIF) and titration, while the surface modifications will be monitored by X-ray Photoelectron Spectroscopy (XPS or ESCA), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and methods for determination of surface energy. A prototype of the device for simultaneous plasma treatment of the polypropilene foil in the metallization chamber will be developed, as well as the system for real time measurements of key plasma and discharge parameters.

    To the best of our knowledge, we are the first research team that has ever performed systematic research on the role of crystallinity on the behavior of polymers in low pressure highly dissociated plasma. We found important differences in the behavior (the interaction probability depends on the degree of crystallinity). Highly cristalline polymers should be treated with more aggressive plasma than amorphous ones, and the required flux of oxygen atoms on the surface of some crystalline polymers should be almost an order of magnitude larger to achieve same effects in terms of surface nanoroughness and functionalization with polar functional groups. Similar results (though not as pronounced) were obtained for the sace of treatment of samples with plasma rich in nitrogen atoms. The long term stability of discharges and low pressure plasma created in atmoshere rich in water vapour is another scientific achivement. We found that radicals created by dissociation of water molecules interact with metallic materials and the result is the loss of surface properties that may eventually lead to instabilities in the DC discharges.

    HEAD: Mozetič Miran

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    Sinteza in funkcionalizacija kompozitnih nanokroglic za zgodnje odkrivanje neurodegenerativnih bolezni (Slovene)

    Applied research project.

    A major drawback of population ageing in developed countries is an enormous increase of neurodegenerative diseases. According to the late statistics, a third of population older than 60 years exhibit symptoms of such diseases. Recent results obtained in European centres for investigation of the diseases showed that they are due to extraordinary increase of the prion-like molecules in the body fluids, especially cerebrospinal fluid and blood. Therefore, it is very important to detect specific disease in its early stage. Since the concentration of prions is very small, there was a need to develop a method for their separation from biological samples. We have developed two new procedures for synthesis of magnetic composite particles. The first procedure includes the synthesis of magnetic liposomes, and the other one includes the synthesis of magnetic sponge particles. Both composite particles have some certain advantages. Liposomes, which are bilayered phospholipid vesicles, are biodegradable particles, while the sponge particles, which are made of calcium carbonate matrix, are more stable particles compared with the liposomes. Both types of magnetic composite particles have many potential uses in medicine. They can not be used just as a method for the separation of specific substances from biological fluids, but also as carriers of therapeutic drugs to the specific targets. With appropriate external magnetic field is be possible to move the magnetic particles to the desired position. By this means we offer a new approach to local treatment of certain diseases.

    HEAD: Alenka Vesel

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    Plasma modification of vascular grafts (Slovene)

    Applied research project. 2009-2012

    The original results on modification of substrates for selective adsorption of cells open a new approach to understanding complex mechanisms involved in interaction between different cells and polymer materials. This is currently a hot topic due to increasing rate of cardiovascular diseases in modern societies. While numerous studies have been performed worldwide, the phenomena are still far from being well understood. Our contribution represents a small fragment but the originality of our approach is promising to explain at least some observations and indicate possible solutions in preventing adsorption of proteins on vascular grafts. The results may lead to development of methods for minimization of platelets activation on vascular grafts thus minimizing the risks of thrombosis. An important scientific impact is detailed study of interaction between blood proteins and surfaces of PET materials since there no a generally accepted theory is available. A handful of hypotheses have been proposed and the list includes our own published recently in respected specialized journal Macromolecular Bioscience. A key scientific result is also the first report worldwide on the reasons for ageing plasma treated materials which reflects in the loss of hemo-compatibility over a period of time. Detailed description and possible explanations for the ageing effects have been revealed in our paper published in a top journal in the field of surface engineering. Worldwide recognition of our results is reflected also in a number of invited lectures given by members of the research team. A selection is given under socio-economic results.

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Metoda za sintezo magnetnih liposomov v električnem polju”

ELERŠIČ, Kristina, MOZETIČ Miran, VESEL Alenka, PAVLIČ Janez Ivan, IGLIČ Aleš, ŽNIDARŠIČ Andrej, KOŠAK Aljoša
Patent SI 23095 (A). Ljubljana: Urad RS za intelektualno lastnino 2009, Pages 15

Interaction of oxygen species With graphene and pyrolytic-graphite surfaces

ELERŠIČ Kristina, ostali
Short article IEEE transactions on plasma science | 2011 | ISSN 0093-3813
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Different types of self-assembled nanostructures on a given substrate can be synthesized via plasma exposure to produce nanoscale devices. In this paper, we seek to understand the microscopic mechanism related to such interactions of plasma radicals by calculating the polarization-induced interaction between oxygen radicals and a given surface, namely, pyrolytic graphite and graphene.

  • graphene
  • oxygen radicals
  • polarizability
  • pyrolytic graphite

Interaction between dipolar lipid headgroups and charged nanoparticles mediated by water dipoles and ions

VELIKONJA Aljaž, BUDIME SANTHOSH Poornima, GONGADZE Ekaterina, KULKARNI Mukta Vishwanath, ELERŠIČ Kristina, PERUTKOVÁ Šárka, KRALJ-IGLIČ Veronika, POKLAR ULRIH Nataša, IGLIČ Aleš
Journal Paper International journal of molecular sciences, Volume 14, Issue 8, 2012, Pages 15312-15329

Abstract

In this work, a theoretical model describing the interaction between a positivelyor negatively charged nanoparticle and neutral zwitterionic lipid bilayers is presented. It isshown that in the close vicinity of the positively charged nanoparticle, the zwitterionic lipidheadgroups are less extended in the direction perpendicular to the membrane surface, whilein the vicinity of the negatively charged nanoparticle, the headgroups are more extended.This result coincides with the calculated increase in the osmotic pressure between the zwitterionic lipid surface and positively charged nanoparticle and the decrease of osmoticpressure between the zwitterionic lipid surface and the negatively charged nanoparticle.Our theoretical predictions agree well with the experimentally determined fluidity of alipid bilayer membrane in contact with positively or negatively charged nanoparticles. Theprospective significance of the present work is mainly to contribute to better understandingof the interactions of charged nanoparticles with a zwitterionic lipid bilayer, which may beimportant in the efficient design of the lipid/nanoparticle nanostructures (like liposomes withencapsulated nanoparticles), which have diverse biomedical applications, including targetedtherapy (drug delivery) and imaging of cancer cells.

Adsorption of protein streptavidin to the plasma treated surface of polystyrene

VESEL Alenka, ELERŠIČ Kristina
Journal Paper Applied Surface Science, Volume 258, Issue 15, 2012, Pages 5558-5560

Abstract

Immobilization of protein streptavidin to the surface of polystyrene (PS) polymer was studied by X-ray photoelectron spectroscopy (XPS). Two different protocols were used to attach streptavidin to the PS surface: physical adsorption and chemical coupling. In both cases the surface properties of PS samples were modified by exposure to cold oxygen plasma for 10 s. Plasma was created in oxygen at 75 Pa by en electrode-less RF discharge. The RF generator operated at 27.12 MHz and the nominal power was about 120 W. The electron temperature was about 3 eV, the plasma density was about 3 × 10 m-3 and the neutral oxygen atom density was about 3 × 1021 m-3. Oxygen plasma treatment caused formation of O-rich functional groups on the surface of PS. The concentration of oxygen was determined by XPS and was about 28 at.%. A thin film of streptavidin was deposited by physical adsorption and chemical bonding. The appearance of streptavidin on the surface was determined from XPS spectra measuring the ratio between N and C peaks. The plasma treatment caused poor adsorption and but strong chemisorption of streptavidin. The results were explained by specific interaction of protein with polar functional groups on the surface of PS after plasma treatment.

Electric-field controlled liposome formation with embedded superparamagnetic iron oxide nanoparticles

ELERŠIČ Kristina, PAVLIČ Janez Ivan, IGLIČ Aleš, VESEL Alenka, MOZETIČ Miran
Journal Paper Chemistry and physics of lipids, Volume 165, Issue 1, 2012, Pages 120-124
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Abstract

Liposomes are one of the most promising biomaterial carriers to deliver DNA,1 proteins, drugs and medicine in human bodies. However, artificially formed liposomes have to satisfy some crucial functions such as: (i) to efficiently carry drugs to targeted systems, (ii) to be biologically stable until they are removed from human body, (iii) to be biodegradable, and (iv) to be sufficiently small in size for effective drug delivery. Here, we report an efficient and novel method to simultaneously manufacture and incorporate super-paramagnetic iron-oxide nanoparticles (efficient target finder in the presence of external magnetic field) into the liposome's interior and its bilayer. In this technique, we use electric field to control the formation of liposomes and the incorporation of iron oxide nanoparticles. Our preparation procedure does not require any chemical or ultrasound treatments. Apart from that, we also provide further experimental investigations on the role of electric fields on the formation of liposomes using XPS and the magnetic-optical microscope.

Morphological alterations of T24 cells on flat and nanotubular TiO[sub]2 surfaces

IMANI Roghayeh, KABASO Doron, ERDANI-KREFT Mateja, GONGADZE Ekaterina, PENIČ Samo, ELERŠIČ Kristina, KOS Andrej, VERANIČ Peter, ZOREC Robert, IGLIČ Aleš
Journal Paper Croatian medical journal, ISSN 0353-9504, vol. 53, no. 6, 2012

Abstract

  • AIM: To investigate morphological alterations of malignant cancer cells (T24) of urothelial origin seeded on flat titanium (Ti) and nanotubular TiO2 (titanium dioxide) nanostructures.
  • METHODS: Using anodization method, TiO2 surfaces composed of vertically aligned nanotubes of 50-100 nm diameters were produced. The flat Ti surface was used as a reference. The alteration in the morphology of cancer cells was evaluated using scanning electron microscopy (SEM). A computational model, based on the theory of membrane elasticity, was constructed to shed light on the biophysical mechanisms responsible for the observed changes in the contact area of adhesion.
  • RESULTS: Large diameter TiO2 nanotubes exhibited a significantly smaller contact area of adhesion (P < 0.0001) and had more membrane protrusions (eg, microvilli and intercellular membrane nanotubes) than on flat Ti surface. Numerical membrane dynamics simulations revealed that the low adhesion energy per unit area would hinder the cell spreading on the large diameter TiO2 nanotubular surface, thus explaining the small contact area.
  • CONCLUSION: The reduction in the cell contact area in the case of large diameter TiO2 nanotube surface, which does not enable formation of the large enough number of the focal adhesion points, prevents spreading of urothelial cells.

Reversible carrier-type transitions in gas-sensing oxides and nanostructures

ARULSAMY Andrew Das, ELERŠIČ Kristina, MODIC Martina, CVELBAR Uroš, MOZETIČ Miran.
Journal Paper Physical chemistry chemical physics, Volume 13, Issue 33, 2011, Pages 15175-15181
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Abstract

Despite many important applications of α-Fe2O3 and Fe doped SnO2 in semiconductors, catalysis, sensors, clinical diagnosis and treatments, one fundamental issue that is crucial to these applications remains theoretically equivocal—the reversible carrier-type transition between n- and p-type conductivities during gas-sensing operations. Herein, we present an unambiguous and rigorous theoretical analysis in order to explain why and how the oxygen vacancies affect the n-type semiconductors α-Fe2O3 and Fe-doped SnO2, in which they are both electronically and chemically transformed into a p-type semiconductor. Furthermore, this reversible transition also occurs on the oxide surfaces during gas-sensing operation due to physisorbed gas molecules (without any chemical reaction). We make use of the ionization energy theory and its renormalized ionic displacement polarizability functional to reclassify, generalize and explain the concept of carrier-type transition in solids, and during gas-sensing operation. The origin of such a transition is associated with the change in ionic polarizability and the valence states of cations in the presence of oxygen vacancies and physisorped gas molecules.

Etching of bacterial capsule and cell wall by oxygen plasma afterflow

ELERŠIČ Kristina,JUNKAR Ita, ŠPES Aleš, VUJOŠEVIĆ Danijela, VRATNICA Zoran, CVELBAR Uroš
Journal Paper IEEE transactions on plasma science, ISSN 0093-3813. [Print ed.], 2011, vol. 39, no. 11, pp. 2972-2973
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Abstract

Sterilization of delicate materials by gaseous plasma represents an interesting task for plasma scientists. While sporulating bacteria are rather resistant to weak plasma treatments, some bacteria are destroyed even in an afterglow. A representative type of nonsporulating bacteria is Staphylococcus aureus. Such bacteria are destroyed by treatment with mostly neutral O atoms found in oxygen plasma afterglow. The degradation steps are followed by atomic force microscopy. The bacteria remain vital for about 2 min of treatment at the O flux of about 1.3×1022m-2·s-1. The bacterial capsule is removed in about 2 min. Once the capsule is removed, degradation of the cell wall occurs, causing bacterial death.

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    Genomics

  • MPS

    President of Student’s council, Jozef Stefan International postgraduate school, Ljubljana, Slovenia. 2010-2011

    Home made cosmetics

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    Soap

  • Currrent Teaching

    • Microscopy

      AFM; SEM

    At My Office

    You can find me at my office located at Technical park, Teslova 30, 1000 Ljubljana SLovenia (room 406 A).

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    At My Lab

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