This project focuses on gamma-radiolytic synthesis of magnetic nanoparticles with the special emphasis on polymer influence. Radiolytic synthesis is a relatively new method of nanoparticle synthesis. By radiolytic procedure, it is possible to synthesize magnetic nanoparticles of controlled size, shape and phase composition. Radiolytic synthesis of nanoparticles begins with radiolysis of water resulting in free radicals (eeq−, H•, •OH, HO2•) and molecular products (H2, H2O2). Hydrated electron (eeq−) and proton radical (H·) are strong reducing agents that are able to reduce metal cations. Polymers in radiolytic synthesis act as dispersants and stabilizers of magnetic nanoparticles in suspensions, as growth and surface modifiers. In this HRZZ project, the influence of various g-irradiation parameters such as dose and dose rate, pH of the precursor solution, on the reducing conditions in suspension, and the phase composition of isolated Fe-oxide nanoparticles will be systematically investigated. Particular attention will be paid to the influence of selected polymers (such as various dextran, PEO, PVP and/or PVA) on the stability of the synthesized magnetic suspensions as well as on the size, shape and phase composition of the formed magnetic nanoparticles. The influence of the average molecular weight of the polymer, the concentration, as well as of the initial polymer/precursor molar ratio will be investigated. The suspensions will be analyzed in detail by Zetasizer and the magnetic particle size determined by the dynamic light scattering method as well as the zeta potential. Microstructural characterization and phase analysis of isolated powder samples will be performed, size and surface of magnetic nanoparticles will be determined (XRD, Mössbauer spectroscopy, FE SEM and HRTEM). In addition, the reducing conditions obtained with certain polymers will be measured by quantitative determination of the concentration of Fe2+ ions produced in irradiated suspensions. Fe2+ concentration will be determined by spectrophotometric and/or redox titration using potassium permanganate solution. In this project, optimal experimental conditions (most suitable polymer, dose and rate of gamma-radiation, pH, Fe3+/polymer ratio) will be found for the radiolytic synthesis of a stable suspension of superparamagnetic nanoparticles. In the final phase, the possibility of radiolytic coating of gold of the surface of the synthesized magnetic nanoparticles (SPIONs), i.e. radiolytic synthesis of composite and/or core-shell iron oxide@Au nanoparticles will be studied. The quality and homogeneity of the gold coating will be tested by UV-Vis spectroscopy and high resolution electron microscopy. The synthesized nanomaterials will be tested as a substrate for surface enhanced Raman spectroscopy (SERS). The use of SPION@Au NČ to determine the micromolar concentrations of organic model molecules present in the aqueous solution will be investigated by surface-enhanced Raman spectroscopy.
HrZZ web page of the project: http://www.hrzz.hr/default.aspx?id=78&pid=6851&rok=2017-05
Published research results available at:https://www.bib.irb.hr/pregled/projekti/HRZZ-UIP-2017-05-7337