ვლადიმერ მიქელაშვილი

The most conventional method for obtaining Fe3O4 or γ-Fe2O3 is chemical co-precipitation. In our work we propose a simple and cost-effective method for obtaining colloidal suspensions composed of Fe3O4 nanoparticles coated with CA and dispersed in a liquid carrier (distilled water). Our particles were synthesized by chemical co-precipitation with ultrasonication (sonolysis) in a low vacuum environment [1,2]. Before coating with CA, the obtained IONPs were processed by electrohydraulic discharges in the high discharge current (HC) (several tens of Amperes) and low discharge current (LC) (several Amperes) modes in water medium using pulsed direct current (PDC). X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS), Ultraviolet-Visible Spectroscopy (UV VIS), and Small Angle X-Ray Scattering (SAXS) were used to characterize the obtained samples.

Breast cancer is the most commonly diagnosed tumor formation in women around the world, which is also the leading cause of female cancer mortality. Although significant progress has been made in the diagnosis and therapy of breast cancer, early detection of disease and antimetastatic treatment still remain a serious problem. The development of the next generation of cancer therapy modalities is relevant in modern oncology. Nanotechnology offers promising prospects in this direction. Recently, the uptake of multifunctional iron oxide nanoparticles, combining both therapeutic and diagnostic capabilities, is gaining increasing attention in terms of cancer treatment, diagnosis, and targeted drug delivery. This study is dedicated to the synthesis of Citric acid-modified Superparamagnetic Iron Oxide Nanoparticles (SPIONs) functionalized with an anti-cancer drug Doxorubicin (DOX), using a controlled chemical co-precipitation method and study in vitro cytotoxicity of obtained magnetic nanofluids (containing Bare, Citric acid-coated, and DOX-loaded IONPs) on 4T1 tumorigenic epithelial cell lines (Figure 1). The synthesized samples were characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Small-Angle X-ray Scattering (SAXS), Vibrating Sample Magnetometry (VSM), and UV-VIS spectrophotometry. To properly analyze and understand the behavior of 4T1 cancer cells after administrating Bare, Citric acid modified, and DOX-loaded IONPs in comparison with free DOX, a complex set of in vitro tests were used, including MTT assay, determination of the cell cycle, and IONPs uptake. Synthesized magnetic nanofluids containing Iron ox-ide nanoparticles (both Bare and modified with citric acid), revealed cytotoxicity on 4T1 cancer cells. However, the results showed the advantage of a combination of doxorubicin and magnetic nanoparticles. The DOX-loaded IONPs were more able to inhibit the growth and proliferation of 4T1 breast cancer cells in vitro, indicating that the system has the potential to act as an antitumor chemotherapeutic agent.

Among the broad range of nanoscale materials such as Fe3O4, γ-Fe2O3, CоFe2O4, ZnFe2O4, BaFe12O19 investigated for biomedical use. Superparamagnetic nanoparticles (SPIONs) of magnetite (Fe3O4) and maghemite (γ-Fe2O3) have attracted significant attention due to their biocompatibility and good magnetic properties, which implies their sensibility to applied external magnetic fields. They can be applied in multifunctional approaches by encapsulation of the particles with a suitable coating substance for controlled drug delivery of therapeutic agents in in vivo applications. Other applications are found in the area of magnetic resonance imaging, tissue repair, immune analysis, biological fluids detoxification, magnetic hyperthermia and cell separation. A simple and cost-effective method was developed to obtain Folic Acid (FA) - conjugated Magnetic Nanoparticles (MNs). Colloidal suspensions composed of a single domain of superparamagnetic iron oxide nanoparticles (SPIONs) dispersed in a liquid carrier (distilled water) were synthesized by in-situ co-precipitation and ultrasonication (sonolysis) in a vacuum environment (0.98 Mpa). Before conjugation obtained MNs were processed by electrohydraulic discharges (see Fig. 1.) in two modes: the high discharge current (HC) (several tens of Amperes) and low discharge current (LC) (several Amperes) mode in an aqueous system using a pulsed direct current (PDC). The processing was performed in a low-pressure reactor at high voltage (1-1.5 kV). HC and LC mode regulated by the distance between discharge rods (from 1.5 to 3 mm). The X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS), Ultraviolet-Visible Spectroscopy (UV-VIS), Vibrating Sample Magnetometry (VSM), Small Angle X-Ray Scattering (SAXS) and Small Angle Neutron Scattering (SANS) were used to characterize obtained samples.

Iron oxide nanoparticles (IONPs) are of great interest for researchers working in different fields of physics, chemistry, biology, and medicine. Growing interest is based on their physical-chemical and pharmacokinetic properties. A well-known method of synthesis of IONPs is chemical co-precipitation. Although this method is distinguished by its simplicity, cheapness, and the possibility of producing in a largescale, its main drawback is that it is impossible to uniformly distribute the concentrations of reactants, and control the nucleation and crystal growth. Small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) were used for the determination of the microscale or nanoscale structure of particle systems in terms of average particle sizes, shapes, size distribution, and surface-to-volume ratio. Additional information was obtained on the colloidal stability, the quality of the dispersion, and the amount and character of the possible particle aggregation. We used Dynamic light scattering (DLS) technique to determine the size distribution profile of small particles in suspension in order to calculate hydrodynamic radius of aspheres. For assessment of stability of colloidal dispersions, we measure the zeta potential of the samples. The magnitude of the zeta potential indicates the degree of electrostatic repulsion between adjacent, similarly charged particles in a dispersion. The proposed approach, as shown by preliminary studies, significantly improves the dispersion of the solution. Strong oscillations associated with the electrohydraulic effect, additionally disperse the chemically synthesized particles. In the present work, we overview trends of the technique of nanomaterial production and processing by pulsed high voltage discharge in solution/water. This work is supported by National Shota Rustaveli National Science Foundation (Grants # # PhDF2016–59 and Ys17–15) and by Central European Research Infrastructure Consortium (Elettra – Proposal No: 20177016). We are grateful to V. Gabunia and E. Sanaia from the I. Vekua Sokhumi Institute of Physics & Technology for their assistance in part of measurements of physical parameters.

Iron oxide nanoparticles containing in magnetic fluids are used in a rapidly expanding number of research and practical applications in the biomedical field magnetic resonance imaging (MRI) contrast enhancements, direct drug delivery systems, hyperthermia treatment as well as labelling and separation of biological materials. In the last decade, increased investigations with several types of iron oxides have been carried out in the field of magnetic NPs, among which magnetite (Fe3O4) and maghemite is the very promising and popular candidates since their good biocompatibility. The main technological challenges are related to the improvement of the following properties: precise control of size, shape, stability, and dispersibility of NPs in desired solvents.

This review is focused on the synthesis of superparamagnetic iron oxide nanoparticles (SPIONs). Iron oxide nanoparticles coated with PVA4–88 was synthesized by two methods: In the first case, iron oxide nanoparticles coating with PVA4–88 is carried out after the synthesis of the magnetic nanoparticles, and in the second case - in the synthesis process. In both cases the Iron oxide nanoparticles were synthesized by suitable modification of the standard synthetic procedure with a controlled co-precipitation technique in one-pot in a vacuum environment. A Co-precipitation technique under vacuum environment was used to prevent undesirable critical oxidation of Fe2+. The obtained PVA coated biocompatible 10-20 nm sized nanoparticle dispersive solution with pH ≈ 7.4 and solid phase content ranging from 0.02-1 % w/v. Prepared iron oxide nanoparticles were characterized using X-ray diffraction (XRD). Particles sizes measured from TEM are approximately 10–20 nm, the magnetic cores exhibit somewhat irregular shapes varying from spherical, oval, to cubic. Also has been investigated magnetic properties. The Vibrating Sample Magnetometer (VSM) studies indicates the presence of superparamagnetic nanoparticles in a magnetic ferrofluid and surfactant influence on the characteristic of the magnetization at room temperatures into high and low magnetic fields. 

This work was supported by Shota Rustaveli National Science Foundation (Grant No. PhDF2016_59)

We propose electrohydraulic discharges assisted chemical co-precipitation technique in order to develop a simple, cost-effective, large-scale manufacturing of bio-applicable iron oxide nanoparticles involving plasma arc discharges in base solution. By this method, as preliminary experiments shows, we obtain better dispersing the formed nanoparticles at the initial stage, process their surface (static stabilization, H and OH radical addition for better absorbance) by pulsed discharges and add to the fluid the bactericidal properties. After that, the covering (stabilizing) of the monodisperse nanoparticles with surfactant is relatively easy to follow, with bioactive molecules (dextran, polyvinyl alcohol, polyethylene glycol, etc.), followed by washing from chemical reaction residuals, additional ultrasound homogenization and centrifugation.

Transition electron microscopy, vibrating sample magnetometer, VIS spectrophotometry and bactericidal research was used to characterize obtaining samples. 

Surface modified superparamagnetic iron oxide nanoparticles (SPIONs) are a kind of novel functional materials, which have been widely used in the various areas. The main requirements to magnetic nanoparticles for biomedical applications are the nontoxicity, biocompatibility and high-level accumulation in the target tissue or organ, chemical stability, simplicity and reproducibility of synthesis. The composition and characteristics of the SPION surface have a strong influence on their stability, distribution, and biocompatibility, with regard to cellular uptake and cytotoxicity. This study is focused on the development of the synthesis of aqueous suspensions of SPIONs stabilized with hydrophilic polymer - polyethylene glycol (PEG). Iron oxide nanoparticles were synthesized via a controlled co-precipitation technique in the vacuum environment. Crystalline structures and particle sizes obtained iron oxide nanoparticles were characterized using X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). Magnetic properties were studied using the Vibrating Sample Magnetometer (VSM). Also, investigated the influence of PEG-coated SPIONs on the viability of the bacterial colonies of the Staphylococcus epidermidis. The detected bactericidal effect was time and growth phase-dependent. The outcomes of this study will further lead to the possible application of SPIONs for human chronic wound healing.

Solar cells (SCs) based on III-V semiconductors are reviewed. Presented work emphases on the Solar Cells containing Quantum Dots (QDs) for next-generation photovoltaics. In this work the method of fabrication of InP QDs on III-V semiconductors is investigated. The original method of electrochemical deposition of metals: indium (In), gallium (Ga) and of alloys (InGa) on the surface of gallium phosphide (GaP), and mechanism of formation of InP QDs on GaP surface is presented. The possibilities of application of InP/GaP/Si structure as SC are discussed, and the challenges arising is also considered.

We consider the effect of nano Fe3O4 doping on the superconducting properties of MgB2. To do this, we for the first time turn on the electrohydraulic effect (Yutkin effect) [4] in a well-known scheme for the treatment (synthesis) of nanoparticles in order to significantly reduce departure from average size of particles and for ensuring the reproducibility of the synthesis process of the composite MgB2- Fe3O4.

Nano- Fe3O4 (of various sizes) doped polycrystalline MgB2 samples were synthesized by encapsulation of well mixed high quality Mg, B and nano- Fe3O4 powders. In order to study the effect of magnetic particles on superconductivity, the composites of (MgB2)0.98(Fe3O4)0.02 was synthesized with former sintered at different temperatures. The superconducting properties were investigated in the case of samples sintering at high temperature (7500C) and at low temperature (3500C).

We have investigated the effect of the addition of several concentrations of magnetite Fe3O4 nanoparticles on the microstructure, critical temperature Tc and the critical current density Jc in the composite MgB2-Fe3O4 material. The study was conducted using X-ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDS) and Vibrating sample magnetometer (VSM) for the magnetization measurements. 

The development of the synthesis of stable aqueous suspensions of superparamagnetic iron oxide nanoparticles stabilized with unmodified polyethylene glycol (PEG) at two molecular weights (4000 and 6000 Da) and dextran-40 has been reported. The obtained biocompatible polymer (PEG)m and dextran coated nanoparticle dispersive solution with pH �?? 6.5 and solid phase content ranging from 0.02-0.75 % w/v has been investigated for optical and magnetic properties. Biomedical application requires the biocompatible superparamagnetic iron oxide nanoparticles (SPION), which are stable and well dispersed in water at physiological pH or in physiological salinity. Biocompatible 10-20 nm sized SPIONs have been synthesized via co-precipitation method in the vacuum environment. These SPIONs have been modified with PEG and dextran in one-pot synthesis. Vibrating Sample Magnetometer (VSM) studies show the effect of phase transformations on the magnetic properties of the nanoparticles and surfactant influence on the characteristic of the magnetization at room temperatures into high and low magnetic fields.

The development of the synthesis of stable aqueous suspensions of

superparamagnetic iron oxide nanoparticles stabilized withunmodified polyethylene glycol

(PEG) at two molecular weights (4000 and 6000 Da) and several PEG/iron ratios has

been reported. The obtained biocompatible polymer (polyethylene glycol -PEG) coated

nanoparticle dispersive solution with pH ≈ 6.5 and solid phase content ranging from

0.02-0.75 % w/v has been investigated for optical and magnetic properties. Biomedical

application requires the biocompatible superparamagnetic iron oxide nanoparticles (SPION), which are stable and well dispersed in water at physiological pH or in physiological salinity. Biocompatible 10-20 nm sized SPIONs have been synthesized via co-precipitation method in the vacuum environment. These SPIONs have been modified with PEG in one-pot synthesis. Vibrating Sample Magnetometer (VSM) studies show the effect of phase transformations on the magnetic properties of the nanoparticles and surfactant influence on the characteristic of the magnetization at room temperatures into high and low magnetic fields.

Magnetic nanoparticles have shown great potential in many biological and biomedical applications such as targeted drug delivery, magnetic fluid hyperthermia, magnetic resonance imaging, and tissue engineering. All these applications require magnetic nanoparticles to be water-soluble and biocompatible. For biological and biomedical applications, magnetic iron oxide nanoparticles are the primary choice because of their biocompatibility and chemical stability. The co‐precipitation method is the most effective technique for preparing aqueous dispersions of iron oxide nanoparticles because the synthesis is conducted in water. For this report, we studied several biological molecules as surface coatings to achieve biocompatibility such as ascorbic acid, polyvinyl alcohol, poly(ethylene glycol) (PEG), and dextran. These molecules were used to control the particle size, prevent the nanoparticles from aggregating, and achieve biocompatibility. The most conventional method for obtaining Fe3O4 is by co-precipitation. The size and shape of the iron oxide NPs depend on the type of salt used (such as chlorides, sulfates, nitrates, perchlorates, etc.), the ferric and ferrous ions ratio, the reaction temperature, the pH value, ionic strength of the media, and the other reaction parameters (e.g. stirring rate, dropping speed of basic solution). But this method needs to be improved in order to raise the monodispersity that is necessary in the case of biomedical applications. To do this, we for the first time turn on the electrohydraulic effect in a well-known scheme for the treatment of nanoparticles in order to significantly reduce the scatter radius of particles. To do this, we have a device created by us that is stationary pilot equipment. As a result, the size radius of particles becomes almost the same, and the particle solubility in water is increased. We carried out the preparation of the magnetic colloid by an adapted co-precipitation method in the presence of an electrohydraulic effect, with further magnetite stabilization. The samples are analyzed by VSM at room temperature to find the saturation magnetization of ascorbic acid-coated iron oxide NPs.

სამედიცინო გამოყენების მაგნიტური სითხის მიღებისას, რომელიც წარმოადგენს კოლოიდურ დისპერსიას ნაწილაკთა მოცულობითი პროცენტული წილით 25 %, აუცილებელია გადაჭრილი იქნას რამდენიმე ამოცანა: აუცილებელია მივიღოთ მცირე (10 – 19 ნმ-ის) ზომის მაგნეტიტის ნაწილაკები და ასევე აუცილებელია დისპერსიული ფაზის ნაწილაკთა დაფარვა სტაბილიზატორის მოლეკულური ფენით, რომელიც ხელს უნდა უშლიდეს ნაწილაკების ურთიერთშეწებებას და ასევე უნდა უზრუნველყოფდეს სითხე-გადამტანში დისპერსირებული ერთდომენიანი მაგნიტური ნაწილაკების მდგრადი კოლოიდური სისტემის წარმოქმნას. დღეს არსებული დისპერგირების მეთოდები, როგორებიცაა ულტრაბგერითი დამუშავება და ცენტრიფუგირება ნაწილობრივ უზრუნველყოფენ ჰომოგენიზაციის კარგ ხარიხს, რაც გამოიხატება სითხეში მიწებებული ნაწილაკების განცალკევებაში, მაგრამ ზოგიერთი აგრეგატის უკვე ჩამოყალიბებული დიდი ზომის შემცირება რთული პროცესია და საჭიროა მაღალი ენერგია მათი კავშირის დასაშლელად. ქიმიური მეთოდით მიღებული Fe3O4 ნანონაწილაკების შემცველი ნანოსითხის ელექტროჰიდრავლიკური მეთოდით დამუშავების უპირატესობა ცენტრიფუგირებისა და ულტრაბგერითი დამუშავების მეთოდებთან შედარებით არის ნანოსითხის ჰომოგენიზაციის მაღალი ხარისხი. ამ მეთოდის არსი მდგომარეობს იმაში, რომ დახურულ ან ღია ჭირჭელში მოთავსებულ სითხეში გავნახორციელოთ განმუხტვა სპეციალური იმპულსის მქონე ელექტრული მუხტით, რის შედეგადაც განმუხტვის ზონის ირგვლივ წარმოიქმნება ზემაღალი ჰიდრავლიკური წნევა, რომელიც ასრულებს სასარგებლო მექანიკურ სამუშაოს, ჩვენ შემთხვევაში ჰომოგენიზაციას. 

დღესდღეობით მეცნიერთა ძალისხმევა მიმართულია ნანომასშტაბური მრავალფენოვანი სტრუქტურების შექმნისაკენ, რომელიც შედგება ფერომაგნიტური მეტალისა და არამაგნიტური ნახევარგამტარის მონაცვლეობითი ფენებისაგან, სადაც შეისწავლება სპინური ინჟექციის, მანიპულაციის, კონტროლისა და დეტექტირების პრობლემები. დიდი მნიშვნელობა ენიჭებათ ნახევარგამტარებს, რომლებიც საუკეთესო სპინურ ინჟექტორებად გვევლინებიან. ამ პრობლემების გადასაწყვეტად შერჩეულია გახსნილი მაგნიტური ნახევარგამტარები, რომლებშიც მაგნიტურ მინარევთა იონები გარკვეული პროცენტული ფარდობითაა წარმოდგენილი(მაგ: 5 ატ %). ასეთი ნახევარგამტარული შენაერთები გამოირჩევიან სპინური პოლარიზაციის მაღალი ხარისხითა და ჰოლის ეფექტით ოთახის ტემპერატურის პირობებში, რაც ერთ-ერთ მნიშვნელოვან წინაპირობას ქმნის სპინტრონული ხელსაწყოს პრაქტიკული რეალიზებისათვის.

ნახევარგამტარების საფუძველზე შექმნილი ნებისმიერი მოწყობილობის ელექტროწრედში ჩასართავად საჭიროა ომური კონტაქტი.   ნახევარგამტარული ნანოტექნოლოგიის განვითარება რამდენიმე ათეული ნანომეტრის ზომის აქტიური ელემენტების შექმნის შესაძლებლობას იძლევა, მაგრამ ასეთი ზომების ომური კონტაქტების მიღება დღესდღეობით მიუღწეველია, ამიტომ მკვლევარები ვარაუდობენ, რომ ნახევარგამტარისა და მეტალის კონტაქტზე მიმდინარე პროცესების კვლევა კიდრვ დიდხანს იქნება როგორც მეცნიერული, ასევე პრაქტიკული მნიშვნელობის აქტუალური ამოცანა.

ჩვენს მიერ შემუშავებული მაგნიტური ნანონაწილაკების მიღების ქიმიური თანადალექვის მეთოდი ორ-საფეხურიანი სინთეზის ტექნილოოგიით წარმოადგენს მაგნეტიტის (Fe3O4) ნანონაწილაკების მიღების დამუშავებულ მეთოდს. იგი მოიცავს, როგორც ნანონაწილაკების მიღების ქიმიურ მეთოდს გარეცხვის პროცედურებთან ერთად, ასევე ნანონაწილაკების სტაბილიზება/სურფაქტაციას, ულტრაბგერით დამუშავებას, ცენტრიფუგირებას და მათ საბოლოო გადამტან სითხეში მოთავსებას. ეს კომპლექსური მეთოდი საყოველთაო თვასაზრისით იძლევა წვრილდისპერსიული ნანონაწილაკების მცირე ზომებს და გამოირჩევა შედარებით მაღალი სტაბილიზაციით გადამტან სითხეში. ამ ყველაფრის ემატება შერჩეული მასალის არატოქსიკურობა და ბიოთავსებადობა, რაც წინაპირობაა სამედიცინო გამოყენებისათვის.

დისერტაციის რეცენზირება

სამაგისტრო ნაშრომების ხელმძღვანელობა

სადოქტორო თემის ხელმძღვანელობა/თანახელმძღვანელობა

უცხოურ ენებზე მონოგრაფიის სამეცნიერო რედაქტირება

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სამეცნიერო პროფესიული ჟურნალის/ კრებულის რეცენზენტობა

რეფერირებული სამეცნიერო ან პროფესიული ჟურნალის/ კრებულის სარედაქციო კოლეგიის წევრობა

საერთაშორისო ორგანიზაციის მიერ მხარდაჭერილ პროექტში/გრანტში მონაწილეობა

სახელმწიფო ბიუჯეტის სახსრებით მხარდაჭერილ პროექტში/ გრანტში მონაწილეობა

პატენტის ავტორობა

უფლება ქართულ ან უცხოურ სასაქონლო ნიშანზე, სასარგებლო მოდელზე

საქართველოს მეცნიერებათა ეროვნული აკადემიის ან სოფლის მეურნეობის აკადემიის წევრობა

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კონფერენციის საორგანიზაციო/ საპროგრამო კომიტეტის წევრობა

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