Radiochemical synthesis of 56Co labelled SiO2 nanoparticles

Objectives: SiO2 nanoparticles (NPs) are used in a wide variety of applications. Fumed silica, which consists of aggregated/agglomerated primary particles of several nm to tens of nm in diameter, is used in many common consumer products. Silica NPs are being developed for novel medical applications, and silica is also used to coat nanoparticles of other compositions. While no major health concerns have been raised regarding silica, NPs in general are under scrutiny regarding their potential risks for human health and the environment. Safety studies require a reliable method for tracing small concentrations of NPs, and radiolabelling is one method that offers significant advantages thanks to the high sensitivity and accuracy of radioactivity measurements. In this study we present a method of synthesising 56Co radiolabelled SiO2 NPs that can be used in such studies. The 56Co was incorporated within the SiO2 structure, in contrast to methods that use externally attached radiotracers. Methods: While other isotopes might also be used, 56Co was selected as a suitable radiotracer as it has a relatively long half life (77 days) and emits well resolved -ray peaks of 847 keV and 1238 keV with high branching ratios (99.9% and 68% respectively). It was produced via the nuclear reaction natFe(p,n)56Co, with a proton beam of 23.5 MeV. Radiochemical separation of 56Co from the Fe target was carried out by cation exchange columns with Dowex 1-X8 (Cl) resin, in order to produce a neutral 56Co solution with a high recovery yield (93%). The obtained pure solution was added to the ingredients for synthesis of silica NPs based on Stöber concept [1]. Various methods (see below) were used to characterise the silica NPs.

CYDZIK Izabela;  BILEWICZ Aleksander;  ABBAS Kamel;  SIMONELLI Federica;  GIBSON Peter; 

2012-01-17

WILEY-BLACKWELL

JRC64682

0362-4803,   

http://onlinelibrary.wiley.com/doi/10.1002/jlcr.1924/pdf,    https://publications.jrc.ec.europa.eu/repository/handle/JRC64682,