title: 7Be-recoil radiolabelling of industrially manufactured silica nanoparticles.
abstract: Radiolabelling of industrially manufactured nanoparticles is useful for nanoparticle dosimetry in biodistribution or cellular uptake studies for hazard and risk assessment. Ideally for such purposes, any chemical processing post production should be avoided as it may change the physico-chemical characteristics of the industrially manufactured species. In many cases, proton irradiation of nanoparticles allows radiolabelling by transmutation of a tiny fraction of their constituent atoms into radionuclides. However, not all types of nanoparticles offer nuclear reactions leading to radionuclides with adequate radiotracer properties. We describe here a process whereby in such cases nanoparticles can be labelled with7Be, which exhibits a physical half-life of 53.29 days and emits γ-rays of 478 keV energy, and is suitable for most radiotracer studies.7Be is produced via the proton-induced nuclear reaction7Li(p,n)7Be in a fine-grained lithium compound with which the nanoparticles are mixed. The high recoil energy of7Be atoms gives them a range that allows the7Be-recoils to be transferred from the lithium compound into the nanoparticles by recoil implantation. The nanoparticles can be recovered from the mixture by dissolving the lithium compound and subsequent filtration or centrifugation. The method has been applied to radiolabel industrially manufactured SiO2nanoparticles. The process can be controlled in such a way that no alterations of the7Be-labelled nanoparticles are detectable by dynamic light scattering, X-ray diffraction and electron microscopy. Moreover, cyclotrons with maximum proton energies of 17-18 MeV that are available in most medical research centres could be used for this purpose.
authors.affiliation: Nanobiosciences Unit, Joint Research Centre, Institute for Health and Consumer Protection, European Commission, T.P.500, Via Enrico Fermi 2749, 21027 Ispra, VA Italy.
authors.forename: Uwe
authors.initials: U
authors.lastname: Holzwarth
authors.affiliation: Nanobiosciences Unit, Joint Research Centre, Institute for Health and Consumer Protection, European Commission, T.P.500, Via Enrico Fermi 2749, 21027 Ispra, VA Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Bellido
authors.affiliation: Nanobiosciences Unit, Joint Research Centre, Institute for Health and Consumer Protection, European Commission, T.P.500, Via Enrico Fermi 2749, 21027 Ispra, VA Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Dalmiglio
authors.affiliation: Department of Radiochemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 11519 Prague 1, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Kozempel
authors.affiliation: Nanobiosciences Unit, Joint Research Centre, Institute for Health and Consumer Protection, European Commission, T.P.500, Via Enrico Fermi 2749, 21027 Ispra, VA Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Cotogno
authors.affiliation: Nanobiosciences Unit, Joint Research Centre, Institute for Health and Consumer Protection, European Commission, T.P.500, Via Enrico Fermi 2749, 21027 Ispra, VA Italy.
authors.forename: Neil
authors.initials: N
authors.lastname: Gibson
keywords: 7Be; Cyclotron; Lithium compounds; Nanomaterials; Nanoparticles; Proton irradiation; Radiolabelling; Recoil