Alkaline Phosphatase-Instructed Self-Assembly of Gadolinium Nanofibers for Enhanced T₂-Weighted Magnetic Resonance Imaging of Tumor

Abstract

Alkaline phosphatase (ALP) is an important enzyme but using ALP-instructed self-assembly of gadolinium nanofibers for enhanced T₂-weighted magnetic resonance imaging (MRI) of tumor has not been reported. In this work, we rationally designed a hydrogelator Nap-FFFYp-EDA-DOTA(Gd) (1P) which, under the catalysis of ALP, was able to self-assemble into gadolinium nanofibers to form hydrogel Gel I for enhanced T₂-weighted MR imaging of ALP activity in vitro and in tumor. T₂ phantom MR imaging indicated that the transverse relaxivity (r₂) value of Gel I was 33.9% higher than that of 1P and both of them were 1 order of magnitude higher than that of Gd-DTPA. In vivo T₂-weighted MR imaging showed that, at 9.4 T, ALP-overexpressing HeLa tumors of 1P-injected mice showed obviously enhanced T₂ contrast. We anticipate that, by replacing ALP with other enzymes, our approach could be applied for MR diagnosis of other diseases in the future.