Preparation of pH-sensitive lipid-modified magnetite nanoparticle dispersion

This paper describes a preparation method for a highly stable magnetite nanoparticle clusters (MNPCs) dispersion using crystalline lipid nanotubes (LNTs). LNTs were used as a coating material owing to their crystallinity. Oleic acid (OA) was employed as a co-dispersant to enhance the dispersibility of the glycolipid-modified MNPCs. The combination of two lipids was effective in producing a stable dispersion; they formed a coating layer on the MNPCs and nanofibers in the dispersion. The nanofibers enhanced the dispersion stability of the MNPCs by forming a network structure. The resulting MNPCs were characterized in terms of morphology, particle size, zeta potential, magnetic properties, re-dispersibility, and biocompatibility. The stability of the dispersion changed with pH. In acidic conditions, most of the MNPCs and nanofibers could be easily removed by using a magnet. The resulting materials have the potential for application in biomedical as well as industrial industries. (C) 2011 Elsevier B.V. All rights reserved.