Liposomal MRI probes containing encapsulated or amphiphilic Fe(iii) coordination complexes

Abstract

Liposomes containing high-spin Fe(III) coordination complexes were prepared towards the production of T1 MRI probes with improved relaxivity. The amphiphilic Fe(III) complexes were anchored into the liposome with two alkyl...

Macrocyclic complexes of Fe(iii) with mixed hydroxypropyl and phenolate or amide pendants as T1 MRI probes

“…For TOAB, the dibenzylamide group was added to DACO via a single step alkylation reaction (Scheme S2 † ). 40 …”

“…Fe(TOAB) was successfully synthesized in aqueous solution with ferrous bromide while maintaining a pH of 5.5 to 6.5 and a temperature of 50 °C. 40 Fe(PTOB) was prepared by using either ferrous chloride or ferrous bromide in ethanol at 60 to 70 °C for 16 to 18 hours. Solutions were exposed to air to allow for oxidation of the ferrous center to ferric iron once bound to the ligands.…”

“… 34 In another example, an amphiphilic analog of Fe(TOAB) was incorporated into the bilayer of a liposome to give a r 1 relaxivity that was increased by 4-fold per iron compared to the free small molecule complex. 40 Incorporation of the mononuclear small molecule iron complexes into a liposome or micelle could be a means to increase the relaxivity of these highly inert, but low relaxivity TACN-complexes that lack an inner-sphere water. Future efforts to increase the relaxivity of Fe( iii ) contrast agents will include scaffolds that link together multiple iron centers.…”

“…For TOAB, the dibenzylamide group was added to DACO via a single step alkylation reaction (Scheme S2 †). 40 To prepare PTOB, the coordinating pendant was added first and the hydroxypropyl groups were added second. This route succeeds in part because the methylsulfonyl protecting group on the phenol remains intact through the harsh acid deprotection of the TACN moiety.…”

Manganese-Based Nanotheranostics for Magnetic Resonance Imaging-Mediated Precise Cancer Management

“…Recently, the use of iron chelates and derived nanoprobes as positive contrast agents shows ideal relaxivity in MRI. 11 , 12 This new research frontier may be a breakthrough direction of Fe-based contrast agents in the future. In contrast, manganese (Mn)-based functional nanomaterials have received much attention in MRI due to their relatively high magnetization spin, fast water particle exchange rate, low side effects, good biocompatibility, crystallinity, and uniformity.…”