Researchers from High Magnetic Field Laboratory of CAS and USTC reported , for the first time, using of MRI methods to study enzymatic hydrogelation  providing a new approach to detect enzyme activity.

Supramolecular hydrogels have been exploited as biomaterials for various applications. However, behaviors of the water molecules encapsulated in hydrogels have not been fully understood.

In this study, scientists designed a precursor 1 which could self-assemble into nanofibers and form hydrogel I (gel I) upon the catalysis of phosphatase. The differences of mechanic property, pore size, water diffusion rate, and magnetic resonance relaxation times T1 and T2 of gel I containing different concentrations of 1 were systematically studied and analyzed.

T1, T2, and diffusion-weighted 1H MR images from gel I phantoms were obtained at 9.4 T MRI. Analyses of the data uncovered how the density of the nanofiber networks affects the relaxation behaviors of the water protons encapsulated in such hydrogels. Rheological analyses and cryo-TEM observations showed increased gel elasticities with increased concentrations of 1 while the pore sizes of gel I decreased. This also resulted in an increase in the proton relaxation rate (i.e., shortened T1, T2, and apparent diffusion coefficient (ADC)) for the water encapsulated in the hydrogel.  

These results entitled Using Magnetic Resonance Imaging to Study Enzymatic Hydrogelation have been published in Journal of Analytical Chemistry.

       Link: http://pubs.acs.org/articlesonrequest/AOR-SU8Yjda2M7mzcuW3jPRR

Figure 1. Schematic illustration of how nanofibers in supramolecular hydrogel affect the relaxation of protons in waters conjugating to them and waters in outer layers.

 

Figure 2. T1-weighted, T2-weighted MR phantom images, and diffusion-weighted MR phantom images of gels formed by different concentrations imaged with a 9.4 T MR scanner.