Effective Detection of Nafion®-Based Theranostic Nanocapsules through ¹⁹F Ultra-Short Echo Time MRI

• Main Authors: Natalia Łopuszyńska, Krzysztof Szczepanowicz, Krzysztof Jasiński, Piotr Warszyński, Władysław P. Węglarz
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Nanomaterials
• Subjects: theranostic nanocarriers; polyelectrolites nanocapsules; imaging; ¹⁹F MRI; ultra short echo time; UTE
• Online Access: https://www.mdpi.com/2079-4991/10/11/2127

The<b> </b>application of the Three-Dimensional Ultra-Short Echo Time (3D UTE) pulse sequence at a high magnetic field for visualization of the distribution of ¹⁹F 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 ¹⁹F content. Before imaging, an MR (magnetic resonance) spectroscopy and T₁ and T₂ measurements were performed, resulting in values of T₂ between 1.3 ms and 3.0 ms, depending on the spectral line. To overcome limitations due to such short T₂, the 3D UTE pulse sequence was applied for ¹⁹F 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 ¹⁹F concentration as low as 1.53·10⁻²mmol ¹⁹F/g of sample, were obtained. This is comparable with the results obtained for molecules, which exhibit more preferable MR characteristics.