Journal of Magnetism and Magnetic Materials 289 (2005) 452–454 Investigation of the interaction between magnetic nanoparticles surface-coated with carboxymethyldextran and blood cells using Raman spectroscopy J.F.B. Santana a , M.A.G. Soler a,Ã , S.W. da Silva a , M.H. Guedes b , Z.G.M. Lacava b , R.B. Azevedo b , P.C. Morais a a Universidade de Brası´lia, Campus Darcy Ribeiro, Instituto de Fı´sica, Nu´cleo de Fı´sica Aplicada, 70910-900 Brası´lia-DF, Brazil b Universidade de Brası´lia, Instituto de Cieˆncias Biolo´gicas Departamento de Gene´tica e Morfologia, 70910-900 Brası´lia-DF, Brazil Available online 30 November 2004 Abstract This study reports on in vitro biological tests performed with a biocompatible magnetic fluid based on carboxymethyldextran-coated magnetite nanoparticles (CMDM). Micro Raman spectroscopy was used to investigate the effect of dispersing (CMDM) nanoparticles in mice blood. We focused our investigation in the use of the Raman spectroscopy for monitoring the hemoglobin structural changes, which may be associated with the oxygen- binding process. r 2004 Elsevier B.V. All rights reserved. PACS: 75.50.Mm; 78.30.j; 83.80.Lz Keywords: Raman spectroscopy; Nanoparticle; Oxyhemoglobin; Carboxymethyldextran; Blood mice; Magnetic fluid 1. Introduction Magnetic nanoparticles offer many attractive possi- bilities for biomedical applications. Their typical sizes are smaller than or comparable to the size of a cell structure, a virus, a protein molecule, or a gene. The magnetic nanoparticles can be engineered by surface coating them with special molecules to interact with or bind to a biological structure, thereby providing a controllable means of targeting specific biological sites. More specifically, magnetic nanoparticles surface-coated with organic molecules can be dispersed as a stable colloid in physiological medium, named biocompatible magnetic fluids, which may be used in magnetic cell separation, drug delivery carriers, hyperthermia treat- ments, and magnetic resonance imaging contrast en- hancement, among others [1–3]. The drawback that mostly concerns the wide use of biocompatible magnetic fluids in new technologies is the possible adverse effect of foreign particles in the organism. In particular, the mechanism of interaction between the surface-coated magnetic nanoparticle and the blood components, for instance, is still not clearly elucidated. After the particles are injected into the blood stream of animals, they are rapidly uptaken (or coated) by macromolecules in the circulation, such as plasma proteins and glycoproteins. The process of particle capture and recognition by the immune system is extremely efficient and can be modulated by particle size and, to an even greater extent, the surface properties [4]. In the investigation of ARTICLE IN PRESS www.elsevier.com/locate/jmmm 0304-8853/$-see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2004.11.127 Ã Corresponding author. Tel.: +55613072900; fax: +55613072363. E-mail address: soler@unb.br (M.A.G. Soler).