Fraunhofer Institute for 
Variable loadable, nanoparticle carrier as contrast agents in magnetic resonance imaging and positron emission tomography
The modern diagnostic imaging in human medicine is characterized by the rapid progress in the instrument engineering. Computer tomography, which already became a classic method, has been replaced by more specialized device alternatives, such as magnetic resonance or positron emission tomography.
Irrespective of the application they are used for (medical or research), these devices require suitable contrast agents for imaging organs and tissues at high resolution. Nowadays, there is a big delay between the rapid development of devices and the slow approval procedure for new contrast agents.
On behalf of Charité Berlin, Fraunhofer IAP developed a new variable loadable type of nanoscale carrier (nanocarrier), which meets the requirements for different equipment systems. These nanocarriers are consisted of two parts. The inner part is represented by a compact, internally networked polymeric core containing fluorescent die. The core is covered by chemically bound corona of water-soluble polymer chains carrying multiple hydrophilic functional groups for the binding of heavy metal ions (via salt formation + complexation).
The described nanoparticle structure ensures the colloidal stability of the contrast agent suspension even in the extreme conditions, such as some used for the loading of radioisotopes (e.g. pH 1 for Ga3+). The heavy metal ions diffuse into the corona of the nanoparticles and get trapped there by the functional groups.
Enriched with indium, gadolinium or gallium, these nanocarriers can be thereby detected by UV detection (1), g-scintigraphy (2) magnetic- (3) or positron emission tomography (4) and be successfully used for the diagnostic imaging.