PEGylated poly(aspartic acid) was a magnetic resonance imaging probe. By grafting with oligoethylenimine and Gd-DTPA, the PEG-PBLA block copolymer was prepared by the ring-opening polymerization of BLA-NCA (β-benzyl-l-aspartate N-carboxy-anhydride) which was promoted by the terminal primary amino group of mPEG-NH2.
The T1 relaxivity of PEG-p(Asp-OEI-DTPA-Gd) was 4.3 times higher than that of Gd-DTPA. As no obvious cytotoxicity was observed from various researches, it showed that the macromolecular contrast agent (mCA) had excellent biocompatibility. Furthermore, researchers labeled Folic acid (FA) onto the mCA which enabled mCA to have the targeting ability, and the in vivo animal studies showed that the FA labeled MRI probes had a significant signal intensity enhancement in the tumor during different time intervals and provided a long and efficient window time for MR examination. To sum up, such kind of mCAs with high efficiency and safety are promising candidates as magnetic resonance imaging (MRI) probes.