Several novel polymers incorporating Gd-DTPA and carbohydrates into the backbone of the polymer were synthesized and studied as potential Magnetic Resonance Imaging (MRI) contrast agents. Trehalose and cyclodextrin polymers were prepared by functionalizing monomeric precursors with cysteamine linkers, polymerizing with DTPA-bis-anhydride, and complexing with gadolinium(III). Mannarate, glucarate, galactarate, and tartrate polymers were prepared by functionalizing monomers with ethylenediamine linkers. Polymers using adipate, succinate, and oxalate moieties in a similar manner were also developed to determine if the presence of hydroxyls affect the relaxivity of the agents.
The relaxivities of all of the polymer systems showed significant increases in relaxivity (37-92%) compared to Gd-DTPA (Magnevist) at 400 MHz and 310K. The carbohydrate-diamine polymers showed the highest relaxivity increases, but the lowest molecular weights, with tartrate polymers demonstrating a 92% increase in relaxivity compared to Gd-DTPA. The trehalose and cyclodextrin polymers were the longest polymers (11-25 kDa), but showed lower relaxivities than polymers using ethylenediamine linkers.