[Preclinical assay on a magnetic carrier type ferrofluid]

The aim of the study was to determine the acute toxicity and the antimicrobial actions of an original magnetic carrier, type ferrofluid. The hydrophilic ferrofluid was prepared by covering the Fe3O4 nannoparticles with ammoniumoleate. The absolute amount of iron was of 40 mg/ml ferrofluid.

Acute toxicity was evaluated on five groups of Swiss male mice, after a single intraperitoneal administration of 1, 0.75, 0.5, 0.25 and 0.125 ml dose of pure ferrofluid/100 g body weight (b.w.), using step-level toxicity method. The study groups of mice were follow-up for 10 days. We did not use the same volume of solution for all the study groups because we were concerned about not to modify the behavior of the ferrofluid (but for each group we used the same volume of solution). The tasks of this part of the study were: 1) the record of the mice death in the first 10 days after intraperitoneal administration of ferrofluid; 2) the behavior of the animal subjects; 3) the morphopathologic examination of kidney, lung, heart, liver and peritoneum samples from the death mice and from the after ten days survivors which were sacrificed. We also investigated the possible antibacterial actions of the ferrofluid on E. coli spp., Klebsiella spp., Staphylococcus aureus Streptococcus group D., in the second part of the study, using standard lab kit. The validation of the results was performed using controls for E. colli and Staphylococcus aureus.

The death of the mice was registered between 24 and finished after 96 hours. The maximum tolerated dose (MTD), was of 0.25 ml (10 mg iron/100 g b.w.) and the lethal dose hundred percent (LD100) was of 0.75 ml/(30 mg iron/100 b.w.). In our study we did not determined any kind of antibacterial action of the ferrofluid.

1) LD100, in our study, was of 30 mg iron/100 g b.w., and DMT of 10 mg iron/100 g b.w. 2) The death of the mice may be due to toxic aggression of ammonium ions released, in vivo, from the ammoniumoleate coverage of magnetite nannoparticles. 3) There were no in vitro antibacterial actions for this ferrofluid.