Determining the microenvironment and protonation state of quercetin encapsulated in pillar[5]arene-based supramolecular nanocarriers

This study reports the optical properties of quercetin encapsulated in self-assembled nanoparticles made from a dicarboxyl-bis-pillar[5]arene/CTAB supramolecular complex, and correlates these properties with the nanoparticle architecture and microenvironment. Experimental evidence indicates that quercetin, in both its neutral and mono-anionic form, is mostly located within the nanoparticle, trapped between the pillararenes. In contrast, only a small fraction of the mono-anionic form is found on the nanoparticle surface. Quercetin is stabilized through hydrogen bonding and hydrophobic interactions, which play a crucial role in protecting the avonol from oxidation and degradation. This stabilization explains our recent ndings on the e cacy of these nanoparticles in delivering and facilitating the cellular internalization of quercetin.