Core-shell superparamagnetic nanoparticles with interesting properties as contrast agents for MRI

摘要

Coreeshell nanoparticles (NPs) formed by superparamagnetic iron oxide NPs (SPIONs) coated withinorganic or organically modified (ORMOSIL) sol gel silica exhibited promising properties as negativecontrast agents (CA) for MRI applications.The potentiality of these new coreeshell NPs as negative CA for MRI is demonstrated and quantified.The longitudinal and transverse relaxivities of NPs with three different coating compositions werestudied at a 7 T magnetic field: silica (TEOS), (3-aminopropyl) triethoxysilane (APTES) and (3-glycidoxypropyl) methyldiethoxysilane (GPTMS).Clearly, it was found that the coreeshell NPs efficiency as CA was strongly depend on the SPIONscoating.All the three coreeshell NPs studied presented a very small effect on the longitudinal relaxation timebut a pronounced one on the transverse relaxation time, leading to a very high transverse longitudinalrelaxivities ratio, decisive for their efficiency as negative CA for MRI.The effect of the coreeshell NPs on the MRI contrast enhancement is obtained and quantified in a setof MRI of agar phantoms obtained at 7 T magnetic field and with a imaging gradient field of 1.6 T/m. Thecoreeshell NPs were tested in Zebra-fish (Danio rerio) animal model. Zebra-fish MRI were obtained withanimals injected with the three coreeshell NPs and the contrast enhancement validated.