Colloidal suspensions of iron oxide and metal iron nanoparticles prepared by laser pyrolysis
have been obtained by coating the particles with dextran in an aqueous media giving rise
to biocompatible ferrofluids. The structural characteristics of the powders and the
size of the particles and the aggregates in the colloidal suspensions have been
analysed and correlated with the magnetic properties of both solids and fluids.
For the first time, to our knowledge, a stable ferrofluid based on metal particles
(<10 nm)
has been obtained with aggregate sizes of nm. In comparison to iron oxide based products, this material exhibits higher saturation magnetization
(45 emu g−1) and
susceptibilities (4000 emu/g T). In addition, the nuclear magnetic resonance response of the ferrofluids has been
measured in order to gain information about the influence of the crystallochemical and
magnetic properties on their relaxation behaviour. The main parameter affected
by the presence of the magnetic nanoparticles is the transversal relaxation time
T2 and the corresponding
relaxivity R2 value that
is of the order of 400 (mmol/l)−1 s−1. It
has been shown that R2
value increases not only by using iron metal instead of iron oxide but also by increasing the
crystal size of the particles. From this study an evaluation of the possibilities of
these materials as contrast agents for magnetic resonance imaging has been made.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.