Effective Detection of Nafion®-Based Theranostic Nanocapsules through F Ultra-Short Echo Time MRI.

The application of the Three-Dimensional Ultra-Short Echo Time (3D UTE) pulse sequence at a high magnetic field for visualization of the distribution of F loaded theranostic core-shell nanocapsules with Nafion® (1,1,2,2-tetrafluoroethene; 1,1,2,2-tetrafluoro-2- [1,1,1,2,3,3-hexafluoro-3-(1,2,2-trifluoroethenoxy)propan-2-yl] oxyethanesulfonic acid) incorporated into the shell is presented. The nanocarriers were formed via the layer-by-layer technique with biodegradable polyelectrolytes: PLL (Poly-L-lysine), and with Nafion®: polymer with high F content. Before imaging, an MR (magnetic resonance) spectroscopy and T and T measurements were performed, resulting in values of T between 1.3 ms and 3.0 ms, depending on the spectral line. To overcome limitations due to such short T, the 3D UTE pulse sequence was applied for F MR imaging. First Nafion® solutions of various concentrations were measured to check the detection limit of our system for the investigated molecule. Next, the imaging of a phantom containing core-shell nanocapsules was performed to assess the possibility of visualizing their distribution in the samples. Images of Nafion® containing samples with SNR ≥ 5 with acquisition time below 30 minutes for F concentration as low as 1.53·10 mmol F/g of sample, were obtained. This is comparable with the results obtained for molecules, which exhibit more preferable MR characteristics.