This project focuses on the development of a gamma-radiolytic method for the synthesis of magnetic nanoparticles, with the special emphasis on influence of polymer. Magnetic iron oxide nanoparticles (MIONPs) have a large application as sensors, contrast agents in MRI, for immunoassays, protein separation, controlled release of drugs, hyperthermia treatment of cancer cells, etc. Radiolytic synthesis (g-irradiation synthesis) is a relatively new, efficient and environmentally friendly method for nanoparticle synthesis, which makes this project fit into the global aspirations of greater application of "green chemistry". The g-irradiation method has advantages over classical methods of nanoparticle synthesis because it does not require the use of toxic/carcinogenic reducing agents, ensures homogeneous and almost instantaneous reduction throughout the system, since hydrated electrons and proton radicals - products water radiolysis - are strong reducing agents that can reduce metal cations, and quite simply, by changing irradiation parameters such as dose, dose rate, atmosphere, etc. allows good control of nanoparticle size, shape and phase composition. However, in contrast to the radiolytic synthesis of noble metals nanoparticles, the radiation synthesis of magnetic nanoparticles has been very poorly investigated. Polymers in radiolytic synthesis act as dispersants and stabilizers of magnetic nanoparticles in suspensions, as well 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 size and 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 dextrans, PEO, PVP and/or PVA). 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 size of magnetic particles determined by the dynamic light scattering method as well as the zeta potential (stability of suspension). Detailed microstructural characterization and phase analysis of isolated powder samples will be performed (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. Optimal experimental conditions 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 on 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.

Published research results available at: https://www.croris.hr/crosbi/searchByContext/7/3554

Purchased equipment (financed by project):

Zetasizer Ultra (Malvern Panalytical)

Instrument for measurement of the size, zeta potential and concentration of micro and nanoparticles and molecules in dispersion or suspension

(the latest generation - unique in the market)

https://www.irb.hr/eng/Divisions/Division-of-Materials-Chemistry/Radiation-Chemistry-and-Dosimetry-Laboratory/Services/Characterization-of-micro-and-nanoparticles-by-the-method-of-dynamic-and-electrophoretic-light-scattering