WP 3 – DESIGN AND TESTING OF ENZYME RESPONSIVE AND/OR VECTORIZED
Lead beneficiary UMONS
Objectives: (i) to develop new contrast agents and contrast switches based on OMRI at earth field, (ii) to assess in vitro their capability to report on specific enzymatic activities, (iii) to test their ability to report on the in vivo detection of tumours and other proteases related diseases
- Description of work
- Task 3.1: achieve the theoretical development in Chemistry and Biology. : seek an in-depth understanding of the structural and dynamic determinants for the design of optimized contrast agents for OMRI (CNRS Marseille, UM, UT); define and implement the biological strategy (targeted enzyme reaction, pathological animal model, etc.) which will be used in the validation steps.
- Task 3.2: develop shift nitroxides and OMRI. A new family of contrast reagents has been designed to be used with OMRI, providing all-or-nothing bright contrast upon protease activation. In this project, nitroxide agents and saturation methods at earth field conditions will be developed. Electronic resonance spectra and theoretical Overhauser enhancement at earth field will be modelled in order to target the most efficient transitions. As soon as the imaging method is showing the expected smart contrasts, the physiological events to be explored will be extended to include new enzymes, new proteases and can also be extended to osidases or lipases. (CNRS Marseille)
- Task 3.3: develop the nanodiamond strategy. Nanodiamonds for MRI at ultra-low magnetic field have been described recently. These systems are able to generate high contrast by OMRI. The efficiency of this method comes from the paramagnetic impurities at nanodiamond surface. This allows the contrast agent to be switched on during the magnetization transfer during the hyperpolarization process. In this project, we will target tumours by active targeting. Nanodiamond can be grafted with specific biovectors, such as folate, RGD peptides, etc. To increase the clearance time of the nanosystems, polyethyleneglycol will be also grafted on the surface (UM)
- Task 3.4: develop activable prodrugs. Liposomes and other nanoparticles (i.e. polylactic and glycolic acid-based NP, hydrogels) will be loaded with Nitroxyl radicals or with “silent” precursors (i.e. hydroxylamine) to prepare the nano-prodrugs responsive to specific enzymatic activity. Target enzymes such as MMPs or phospholipases will trigger the NP degradation allowing (i) the release of the “quenching” for the Nitroxyl radicals or (ii) the transformation of the “silent” precursor into radicals suitable for the OMRI experiment. Passive and active targeting of NPs will be pursued (including functionalization to cross biological barriers) (UT).
- Task 3.5: verify the OMRI feasibility of all the new contrast agents by EPR spectroscopy or DNP enhancement. Follow up of an enzymatic reaction in vitro.
- Task 3.6: verify the contrast switch feasibility in vitro for all contrast agents
- Task 2.4: implement, tune and test the acquisition sequence (CNRS Bordeaux and FH)