This study reports the development of a completely new class of MRI contrast agents, displaying remarkable relaxation effects in the absence of paramagnetic metal ions. Their detection requires the acquisition of images at variable magnetic field strength as provided by fast field cycling imaging scanners. They contain poly-histidine chains (poly-His), whose imidazole groups generate N-14-quadrupolar-peaks that cause a relaxation enhancement of water protons at a frequency (1.38 +/- 0.3 MHz) that is readily detectable from the frequencies associated with endogenous proteins. The poly-His quadrupolar peaks are detectable only when the polymer is in a solid-like form, that is, at pH>6.6. Above this value, their intensity is pH dependent and can be used to report on the occurring pH changes. On this basis, the poly-His moieties were conjugated to biocompatible polymers, such as polylactic and glycolic acid, in order to form stable nanoparticles able to encapsulate structured water in their core. FFC images were acquired to assess their contrast-generating ability.

A Novel Class of 1 H-MRI Contrast Agents Based on the Relaxation Enhancement Induced on Water Protons by 14 N-Containing Imidazole Moieties

Baroni, Simona;Stefania, Rachele;Aime, Silvio;Geninatti Crich, Simonetta
2021-01-01

Abstract

This study reports the development of a completely new class of MRI contrast agents, displaying remarkable relaxation effects in the absence of paramagnetic metal ions. Their detection requires the acquisition of images at variable magnetic field strength as provided by fast field cycling imaging scanners. They contain poly-histidine chains (poly-His), whose imidazole groups generate N-14-quadrupolar-peaks that cause a relaxation enhancement of water protons at a frequency (1.38 +/- 0.3 MHz) that is readily detectable from the frequencies associated with endogenous proteins. The poly-His quadrupolar peaks are detectable only when the polymer is in a solid-like form, that is, at pH>6.6. Above this value, their intensity is pH dependent and can be used to report on the occurring pH changes. On this basis, the poly-His moieties were conjugated to biocompatible polymers, such as polylactic and glycolic acid, in order to form stable nanoparticles able to encapsulate structured water in their core. FFC images were acquired to assess their contrast-generating ability.
2021
60
8
4208
4214
biosensors; contrast agents; magnetic resonance imaging; nanoparticles; peptides
Baroni, Simona; Stefania, Rachele; Broche, Lionel M; Senn, Nicholas; Lurie, David J; Ross, P James; Aime, Silvio; Geninatti Crich, Simonetta
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1765409
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