HR-MAS NMR: A tool to study the molecular state of guests encapsulated in cyclodextrins-based polymers.

Nanosponges are cyclodextrin-based crosslinked polymers, consisting in a three dimensional network with cavities of different dimension (depending on cross-linker agents). where drug molecules can be stored. This novel class of materials is capable of carrying both lipophilic and hydrophilic substances and of improving the solubility of poorly water-soluble molecules. Despite the growing importance of these compounds, a complete characterization in term of molecular structure is still missing. This is mainly due to the difficult of investigation caused by different swelling capability, the largely amorphous state and the high degree of reticulation. High Resolution Magic Angle Spinning (HR-MAS) NMR is a powerful tool for studying structural and dynamic properties of supramolecular gels and for the assessment of the molecular environment of molecules or ions encapsulated into the polymeric network. In this work we present the potentiality of HR-MAS NMR for studying: -state of guest inside the pores of the polymeric network. -self-diffusion properties of both water and guest molecules inside the nanosponge cavities. Self-diffusion coefficients were measured by pulsed field gradient spin-echo (PGSE) NMR experiments.