Tehnologija izdelave Au nano-delcev (Slovene)

Nowadays, state-of-the-art nanotechnologies enabled the synthesis and functionalization of Au nano-particles with well-controlled shapes, sizes and structures providing a toolbox that did not exist before. The development of an aerosol route (ultrasonic spray pyrolysis) seems to be essential for the synthesis and manipulation of anisotropic Au nanoparticles, with the major requirements such as the control of the nuclei shape, growth on specific facets, etc. Further efforts would focus on a better understanding of the growth mechanisms for best-shape selectivity, in order to find a suitable application. Objectives and key challenges of our project proposal are: 1. Synthesis of Au nano-particles with well-controlled shapes, sizes and structures, by ultrasonic spray pirolysis 2. Comparative analysis of characteristics for spherical and non-spherical (rods, wires, cubes, triangular prisms) Au nano-particles 3. Characterization of flow and heat transfer characteristics in nanofluids 4. Investigation of the biocompatibility of the Au nano-particles in vitro and in vivo 5. Application of Au nano-particles for dental/medical purposes - To design prototypes of devices for nanoparticles - To develop appropriate in vitro tests for the biological application of bare or conjugated Au nano-particles (1) Ultrasonic spray pyrolysis (USP) is an innovative and powerful tool for the synthesis of particles with controlled and uniform particle size, because of easy powder morphology control and the availability of cheap precursors. The main aim would be to investigate the possibility of producing gold nanoparticles from a water solution bearing gold. (2) The study of a sample with narrow size and shape distribution would be essential for determining the physical and chemical properties of individual particles in assemblies and mixtures. Therefore different technique for characteisations woulld be used. (3) Heat and flow characteristics of dilute liquid suspensions of nanoparticles (a.k.a. nanofluids) in various geometries will be investigated. Performance of Au nanoparticles will be studied in details and compared with Cu, Al2O3 and TiO2 nanoparticles. We will focus on most important flow and heat transfer characteristics of nanofluid flows in two- as well as in three-dimensional geometries for different volume fractions of nanoparticles. The numerical analysis will be performed using the finite volume method to solve the system of non-linear governing equations of nanofluid flows. Physical properties of nanofluids (for example effective viscosity, effective thermal conductivity) will be modelled by different relationships that can be found in the open literature. Results of thorough and detailed numerical analysis will contribute to a detailed knowledge in the field of heat and flow characteristics of different types of nanofluids (4) Observing the properties of the new biomedical spherical and anisotropic gold structures regarding self-assembled monolayers is to be expected as the electrical fields connected to the plasmon resonance will now influence the effective fields around the neighbouring nanoparticles. With continued development of their synthesis and assembly, gold nanoparticles will be a standard stock of future photonics, biomedical and catalytic applications. (5) Some literature reports suggest that nanogold structures may interfere with cell functions and cause cytotoxic, pro-inflammatory or anti-inflammatory effects. The reason for such effects could be due either to the phagocytosis of nanogold particles and subsequent modification of cellular functions, which are different from the influence of the released Au ions. In addition, some contaminants present during nanogold preparation (metals, catalysts, organic solvents, environmental contaminants), may act synergistically or antagonistically with nanogold structures. Therefore, biocompatibility studies of prepared nanogold particles are a necessary research step.

Nowadays, Au nanoparticles are increasingly being mentioned in modern medicine. These are nanoparticles with dimensions below 100 nm. As such, they have several properties that distinguish them from materials with larger dimensions. These properties are: chemical reactivity, energy absorption and biological mobility. Because of these characteristics, they can be used as contrast agents in medicine, or as carriers of genes for delivery to individual cells. In some cases, the Au nanoparticles allow analyses and therapies, which can not be performed otherwise. Investigations by means of transmission electron microscopy (TEM) of different Au nanoparticles have successfully contributed to the understanding of their synthesis by ultrasonic spray pyrolysis (USP) and control of their morphology. Further, investigations and their results contribute to a better understanding of the structure of Au nanoparticles. The research results were presented at international scientific meetings and published in international scientific journals. Results, gained during the project and presented in many scientific papers, indicate the original approach in analysing the nanofluids' heat transfer characteristics. In contrast to most (if not all) authors we have shown the following: • adding of nanoparticles in a base fluid delays the onset of the convective heat transfer mechanism during the natural convection • adding of nanoparticles in a base fluid reduces the mean Nusselt number value Aforementioned is (partly) proved by the pure citations of original scientific papers incurred during the period of the research project L2-4212. We performed the cytotoxicity study of the Au nanoparticles along with their immunomodulatory properties - what represents pioneer work in the scientific area of biomaterials.

Project’s research results clearly dictate the need for further numerical analyses in the field of nanotechnology, e.g.: • comparison of theoretical models for thermo-physical properties of nanofluids and analysis of their suitability/ appropriateness; • analysis of the evaporation of aerosol droplets, solvent diffusion and determination of the optimal temperature conditions during the continuous production of nanoparticles for medical use. Consequently, Au nanoparticles are being intensively studied for their effects on health. Nanoparticles also represent unique environmental and social challenges, particularly in relation to toxicity. Research in the framework of the project "Production technology of Au nanoparticles' has contributed to the further development and upgrading of the production of Au nanoparticles, especially in Slovenian industrial companies Zlatarna Celje d.d. and Tren d.o.o., and this brought new potentials in the development and production of Au nanoparticles to both companies. The project also connected researchers from Europe (Slovenia, Germany) and the Balkan countries (Serbia) and thus contributed to acquire and transfer of new knowledge.