Synthesis of 5-Fluorouracil Polymer Conjugate and F NMR Analysis of Drug Release for MRI Monitoring.

To monitor the release of fluorinated drugs from polymeric carriers, a novel F MRI enzyme-responsive contrast agent was developed and tested. This contrast agent was prepared by conjugation of 5-fluorouracil (5-FU) to hyperbranched poly(,-dimethylacrylamide) (HB-PDMA) via an enzyme-degradable peptide linker. Due to the different molecular sizes, the release of 5-FU from the 5-FU polymer conjugate resulted in a sufficiently substantial difference in spin-spin F NMR/MRI relaxation time that enabled differentiating between attached and released drug states. The 5-FU polymer conjugate exhibited a broad signal and short relaxation time under F NMR analysis. Incubation with the enzyme induced the release of 5-FU, accompanied by an extension of relaxation times and an enhancement in the F MRI signal. This approach is promising for application in the convenient monitoring of 5-FU drug release and can be used to monitor the release of other fluorinated drugs.