ORGANIZATION
The work of the VINCENT Center of Excellence is organized through six Departments:
- Department of Nanomaterials Synthesis;
- Department of Structure and Microstructure Analysis;
- Department of Magnetism and Computer Modeling;
- Department of Magnetic Hyperthermia and Biosensors;
- Department of Radiolabeled Nanomaterials;
- Department of Biological Research.
The Center is managed by a board consisting of heads of departments and the head of the Center, Dr Zeljko Prijovic.
Department of Nanomaterials Synthesis
The department is equipped for the application of various methods of nanomaterial synthesis, including the simple coprecipitation method, the microwave-assisted method, polyol-mediated as well as thermal decomposition method.
- Microwave-assisted method
Using this two-stage approach, the system is homogenously heated by microwaves without thermal gradient effects which lead to nanoparticles with a relatively narrow size distribution. In the first phase, amorphous and partially crystallized particles are precipitated from the corresponding salts in an inert atmosphere. The second phase includes hydrothermal-microwave treatment in a microwave device. Nanoparticles, which are obtained under these conditions, have better crystal properties, as well as specific morphological properties, which can be tuned for their potential application. The new generation of commercial microwave device ETHOS EASY, Milestone, Italy is used. The microwave-assisted route can be performed as hydrothermal or solvothermal using different organic solvents.
- Polyol-mediated method
In the polyol process, the liquid polyol acts as the solvent of the metallic precursor, the reducing agent, and in some cases as a complexing agent for the metallic cations. The solution of iron salts is stirred and heated to a given temperature reaching the boiling point of the polyol (usually above 220 °C). By controlling the kinetics of the precipitation, dispersed metal oxide nanoparticles with well-defined shapes and sizes can be obtained. Better control of the average size can be obtained by seeding the reactive medium with foreign particles (heterogeneous nucleation). In this way, nucleation and growth steps can be completely separated, which results in uniform particles. Polyol-mediated synthesis can be performed at atmospheric pressure as well as solvothermal using the sealed autoclave.
- High-temperature decomposition of organic precursors
The decomposition of iron precursors in the presence of hot organic surfactants has yielded markedly improved samples with excellent size control, narrow size distribution, and good crystallinity of individual and dispersible magnetic nanoparticles.
The head of the department is dr Marija Mirković. [top of page]
Department of Structure and Microstructure Analysis
The task of this department is to enable detailed analysis of the structure and microstructure of nanoparticles, which gives the feedback on the synthesis process and helps in the selection of successfully synthesized samples. The department provides the following important information on the synthesized nanomaterials:
– composition of the crystalline phase (phase identification),
– details of the crystal structure,
– average morphological properties of particles (mean size of crystal domains and their shape, type and concentration of defects),
– surface characteristics of particles (coatings),
– hydrodynamic radius of particles in suspensions and their zeta potential.
The most important technique utilised is X-ray diffraction, which is performed on two powder sample diffractometers and one single crystal diffractometer: Bruker D8 Advance, Rigaku Smart lab 3kW, and Enraf Nonius CAD4. A wide range of different analyses are exploited, from standard powder and single crystal reflection geometry, to emulsions and small angle scattering (SAXS).
Infrared spectroscopy is performed on a Nicolet iS50 FT-IR device, and it is extremely important for the characterization of success/failure in the coating of nanoparticles, but also for the detection of possible contamination remaining from the synthesis process.
The department also possesses a Malvern Nano-ZS90″zeta-sizer” device which completes the process of characterization of nanoparticles in liquid suspension, and determines their hydrodynamic radius. The head of the department is dr Jovan Blanuša. [top of page]
Department of Magnetism and Computer Modeling
The task of this department is twofold:
– experimental characterization and analysis of the magnetic properties of synthesized nanoparticles,
– theoretical modeling of magnetic interactions.
Experimental characterization of magnetic nanoparticles is done on the Quantum Design MPMS XL-5 SQUID magnetometer. With the addition of options such as extended dynamic range, low fields capability, AC susceptibility, and magnetoresisitance measurements, a wide range of magnetic phenomena can be studied. The important role of this department is to provide insight into connection between magnetic phenomena and the chemical composition, structural and microstructural properties of the tested nanomaterial by systematic investigation of magnetic properties. The established correlations are used to further adjust the synthesis process, in order to optimize those magnetic properties that are crucial for a targeted application.
In addition to the magnetic characterization of the averaged voluminous response by using SQUID magnetometry, the department also utilises Mossbauer spectroscopy as a complementary method to examine the local properties of magnetic ions. Mossbauer MS4 Spectrometer is equipped with a cold head for operation in the interval 10 – 320 K and optimized for resonant absorption of gamma radiation of iron ions. Of great interest is the sensitivity of this method to magnetic relaxations, which is its main advantage to be used here to examine the dynamics of magnetic moments.
Theoretical modelling is based on the DFT-BS (Broken Symmetry) approach, in order to predict the influence of geometric and electronic structure on magnetic interactions. The head of the department is dr Vladan Kusigerski. [top of page]
Department of Magnetic Hyperthermia and Biosensors
The most important role of this department is calorimetric testing of the heating power of magnetic nanoparticles. For this purpose, the department is equipped with a multifunctional device DM100 (nB nano Scale Biomagnetic, Zaragosa, Spain) which allows testing the heating power of magnetic nanoparticles in suspension (ferrofluid calorimetry), as well as magnetic hyperthermia tests on cell lines (in vitro) and on small laboratory animals (in vivo).
In addition to this device, the Department is equipped with an original AC magnetometer for measuring dynamic hysteresis, which is a home built device. This device analyzes poorly conducting powder, solid or liquid samples up to 1 ml. It is used to determine the heat loss of a magnetic system in a changing magnetic field. Also, the dynamic properties of magnetic materials are studied, since dynamic hysteresis depicts the unbalanced state of the system and is suitable for examining relaxation phenomena.
Biosensors – the department also performs research on the application of nanomaterials in the design of electrochemical sensors, by using the Autolab PGSTAT302N device, which includes both a potentiostat and a galvanostat. The most important areas covered by this instrument are: analytical chemistry and environmental chemistry, biotechnology/biosensors, corrosion and electrochemistry.
The head of the department is dr Bratislav Antić. [top of page]
Department of Radiolabeled Nanomaterials
The activities of this Department comprehend research in the fields of physico-chemical, chemical, pharmaceutical and medical sciences. Due to the specifics of working with radioactive material, all activities are located in the Laboratory for Radioisotopes (link ka sajt Lab070), in the part that has specific protection measures for work with radioactive material.
The following activities take place in this Department:
• design of radiolabeled nanomaterials;
• radiolabeling optimization;
• testing of physico-chemical properties of labeled compounds by different techniques based on measurement of radioactivity of the tested material (HPLC with gamma detector, ITLC, gel and ion- exchange chromatography, extraction);
• testing of biochemical and biological properties of labeled nanomaterials (in vitro stability tests, in vitro cell culture tests);
• in vivo testing of biodistribution on small laboratory animals.
The devices used to measure radioactivity in the department are: dose calibrator (Capintec CRC 15), TLC scanner (Scan-Ram PET/SPECT radio-TLC scanner Lablogic), gamma counters (Perkin Elmer Wizard 1480, Gamma 333 ICN Tracerlab, and Compu Gamma 1282, LKB).
Diagnostic radioisotope technetium-99m is used for radiolabeling due to its short half-life (6 hours) and gamma photon energy (142 keV), which is suitable for detection by a gamma camera. Beta emitters are used for therapeutic purposes, and the most commonly used radiolabeling of nanomaterials are iodine-131, lutetium-177, and yttrium-90.
The specific goal in this area is to provide radiolabeled nanomaterials as metabolically stable – they must not be metabolized before reaching the target organ and must remain in the organ long enough to perform all necessary tests. Tests of biodistribution over time are monitored as part of in vivo stability studies. The head of the department is dr Sanja Vranjes Djuric. [top of page]
Department of Biological Research
Within the biological department, all types of tests on tissue culture, biochemical analyses and in vivo tests on small laboratory animals are performed. For the purpose of testing the efficiency of different types of therapy (hyperthermia, radionuclide, combined), the vivarium was built for immuno-compromised animals. The study of the interaction of nanomaterials and living systems is monitored at the level of organisms and at the molecular level.
The department uses an isolated tissue culture room, equipped with ventilation that includes HEPA filters, sterile class II laminar flow cabinets for culture of animal and human cells (including tumor cells), in vivo imager, inverted microscope with phase contrast and the possibility of fluorescent lighting, incubator with controlled temperature, humidity and CO2 atmosphere.
Biochemical analyses are performed on standard equipment for isolation and analysis of biomolecules (both small molecules and macromolecules). The department also use a PCR, Cryotome, an agar electrophoresis device and an appropriate visualization system, a bathroom with a thermostat, and standard equipment for molecular biology (centrifuge, vortex, etc.).
Surgical procedures on animals are performed in a dedicated sterile cabinet with laminar flow. All procedures are performed in accordance with applicable national and international regulations and standards. The head of the department is dr Željko Prijović. [top of page]