Magnetite Colloids

Magnetic Resonance Tomography (MRT) is a modern technique of diagnostic imaging, which allows visualization of cross-sectional images of the human body. MRT is a non-invasive imaging of the tissues, which provides a better resolution for soft tissue imaging than classic radiation-based imaging techniques. However, it was shown, that the resolution of the MRT images could be even more improved using additional contrast agents. For example, iron-based ferrofluids colloids made of magnetite or maghemit nanoparticles are powerful contrast agents for MRT. But usually, such contrast agents are only useful for liver imaging. The latter is a consequence of a fast clearance of the particles out of the bloodstream into the liver reticulo-endothelial system. Thus, iron-based colloids usually only permit to distinguish healthy liver cells from tumor liver cells.

The main goal of our project is to design new ferrofluids-based organ-specific MRT contrast agents, which won't be only restricted to liver imaging. For achieving such goal, the surfaces of the nanoparticles should be functionalized with various organ-specific ligands but also modified in order to increase the lifetime of the particle in the bloodstream. The latter can be done by coating the particles surfaces with polyethylene oxide (PEO), a polymer known to prevent plasma protein adsorption in vivo. Thus, our contrast agents are made of magnetite particle possessing a nanometer scale diameter coated with chimera diblock copolymer PEO-polypeptide. The first role of the negatively charged polypeptide (poly(glutamic acid) or poly(aspartic acid)) is to interact with the positively charged surface of the magnetite particles. But also, these polypeptide layers could be potentially used as a drug containers for drug delivery. Therefore, our colloids combine diagnostic and therapy possibilities. Such concept is extremely innovative and is currently under investigation in vitro (cell culture) and in vivo (rats).