Biophys J, May 2001, p. 2483-2486, Vol. 80, No. 5

Magnetic Resonance of a Dextran-Coated Magnetic Fluid Intravenously Administered in Mice

L. M. Lacava,^* Z. G. M. Lacava,^* M. F. Da Silva, O. Silva, S. B. Chaves,^* R. B. Azevedo,^* F. Pelegrini, C. Gansau,^§ N. Buske,^§ D. Sabolovic,^¶ and P. C. Morais

 ^*Instituto de Biologia, Universidade de Brasília, 70910-900 Brasília (DF), Brazil;  Instituto de Física, Núcleo de Física Aplicada, Universidade de Brasília, 70919-970 Brasília (DF), Brazil;  Instituto de Física, Universidade Federal de Goiás, 74001-970 Goiânia (GO), Brazil;  ^§Mediport Kardiotechnik GmbH, Wiesenweg 10, D-12247 Berlin, Germany; and  ^¶INSERM Unité 511, Faculté de Médicine Pitié-Salpêtrière, Paris Cedex 13-75643, France

Magnetic resonance was used to investigate the kinetic disposition of magnetite nanoparticles (9.4 nm core diameter) from the blood circulation after intravenous injection of magnetite-based dextran-coated magnetic fluid in female Swiss mice. In the first 60 min the time-decay of the nanoparticle concentration in the blood circulation follows the one-exponential (one-compartment) model with a half-life of (6.9 ± 0.7) min. The X-band spectra show a broad single line at g  2, typical of nanomagnetic particles suspended in a nonmagnetic matrix. The resonance field shifts toward higher values as the particle concentration reduces, following two distinct regimes. At the higher concentration regime (above 10¹⁴ cm³) the particle-particle interaction responds for the nonlinear behavior, while at the lower concentration regime (below 10¹⁴ cm³) the particle-particle interaction is ruled out and the system recovers the linearity due to the demagnetizing field effect alone.

Biophys J, May 2001, p. 2483-2486, Vol. 80, No. 5
© 2001 by the Biophysical Society   0006-3495/01/05/2483/04  $2.00