Preparation and performance of biocompatible gadolinium polymer as liver-targeting magnetic resonance imaging contrast agent

A biocompatible macromolecule-conjugated gadolinium chelate complex (PAV 2 -EDA-DOTA-Gd) as a new liver-specific contrast agent for magnetic resonance imaging (MRI) was synthesized and evaluated. An aspartic acid–valine copolymer was used as a carrier and ethylenediamine as a chemical linker, and the aspartic acid–valine copolymer was covalently linked to the small molecule MRI contrast agent Gd-DOTA (Dotarem) to synthesize a large molecule contrast agent. In vitro MR relaxation showed that the T 1 -relaxivity of PAV 2 -EDA-DOTA-Gd (13.7 mmol −1  L s −1 ) was much higher than that of the small-molecule Gd-DOTA (4.9 mmol −1  L s −1 ). In vivo imaging of rats showed that the enhancement effect of PAV 2 -EDA-DOTA-Gd (55.37 ± 2.80%) on liver imaging was 2.6 times that of Gd-DOTA (21.12 ± 3.86%), and it produced a longer imaging window time (40–70 min for PAV 2 -EDA-DOTA-Gd and 10–30 min for Gd-DOTA). Preliminary safety experiments, such as cell experiments and tissue sectioning, showed that PAV 2 -EDA-DOTA-Gd had low toxicity and satisfactory biocompatibility. The results of this study indicated that PAV 2 -EDA-DOTA-Gd had high potential as a liver-specific MRI contrast agent.