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Contrast agentGeometric confinementMagnetic resonance imagingPolysaccharide nanoparticlesRelaxivity


Process for the preparation of nanoparticles of a cross-linked polysaccharide having an appropriate cross-linking agent, within which a gadolinium or manganese-based contrast agent is geometrically confined. This preparation process is based on the use of microfluidic devices and the control of temperatures, flows and respective concentrations in the various stages of the process, so as to obtain a final product of nanometer size in which the metal, thanks to its geometric confinement in the reticule of the cross-linked polysaccharide, it has a greater relaxivity, useful for increasing the contrast of images in magnetic resonance imaging, or in combination with other diagnostic imaging techniques or more generally in nuclear medicine.

Technical features

To date, new contrast agents based on gadolinium or manganese encapsulated inside biopolymers have been proposed, in order to improve their relaxivity, a parameter that determines the contrast of the images provided in MRI. However, these biopolymers have shown problems with cytotoxicity and poor efficiency, in addition to the need for additional recovery and purification steps, resulting in increased costs. Due to the geometric confinement of gadolinium or manganese within cross-linked polysaccharide nanoparticles, an increase in relaxivity was observed about 10-12 times higher than that of common contrast agents, resulting in highly biocompatible. In fact, unlike encapsulation, as with state-of-the-art polymer matrices, gadolinium/manganese interacts with cross-linked polysaccharide molecules creating a rigid structure in which metal ions are locked in a certain position. This rigidity of the nanostructure implies a reduced mobility of the water molecules present in the tissues where the nanostructure goes, maximizing the reception of the MRI signal.

Possible Applications

  • Contrast agent for magnetic resonance imaging (MRI)


  • Significantly increased relaxivity
  • Biocompatible and, thanks to nanometric size, eliminated naturally through the kidneys
  • Possibility to bind nutraceutical components and/or drugs to the nanoparticles
  • Highly stable compounds in the long term