Gamma-irradiation applied in the synthesis of metallic and organic nanoparticles: A short review

Controlled synthesis of nanostructured materials allows the development of new materials with fine-tuned mechanical, optical, magnetic, electronic, conductive, and catalytic properties that are used in numerous applications for example in medical area as vehicles for drug delivery, in diagnostics or combinations thereof. Advantages of using radiation chemistry for this purpose are many, minimal use of potentially harmful chemicals and simple production schemes in aqueous systems, which minimizes the use of organic solvents and the need for separation and purification of the final product. High energies particularly gamma-rays (1.17 and 1.33 MeV from 60Co) can be used to initiate free radical based reactions in solids, liquids or gases and because of non-selectivity of absorption of gamma-rays in matter free radicals and electrons that are dependent on the factor G. These radiolitycal species in aqua solution are extensively used in the synthesis of metallic nanoparticles (NPs) from its corresponding salts. However, in the case of organic NPs, the gamma-rays are used mainly to stabilize by cross-linking preformed NPs from natural or synthetic polymers and proteins, or in any case, start polymerisation reactions from monomers that become to form the NPs. Therefore, the unique properties of ionizing radiation make it a very useful tool in the synthesis of a broad variety of metallic NPs with several compositions by a combination of different metal ions, polymers, monomers, and even proteins, giving core-shell and alloyed NPs. This method of synthesis represents a clean alternative to chemical methods and it has shown huge potential in morphological control and particle size by means of parameters that include absorbed dose, dose rate, stabilizing agents, and concentration of metal ion, polymer/monomer, and protein precursors. In this work, we reviewed the synthesis of metallic and organic NPs through gamma-rays with prospects for a future outlook.