Mitigating Mucoadhesion of β–Cyclodextrins via PEGylation: Insights from ¹⁹F Diffusion NMR Analysis

β–Cyclodextrin (β–CD)-based materials are widely used in drug delivery, yet their interactions with mucosal barriers remain insufficiently understood. Because the mucus layer coating epithelial surfaces can hinder drug transport, elucidating β–CD–mucin interactions is critical for optimizing cyclodextrin-based carriers. In this study, we examined whether PEGylation can attenuate the mucoadhesive behavior of β–CD. Monomethoxy poly(ethylene glycol)-modified β–CDs (MPEG–β–CDs) were evaluated using ¹⁹F self-diffusion NMR spectroscopy coupled with a kinetic diffusion model describing reversible binding to stationary substrates. Mucin hydrogels were prepared from bovine submaxillary mucin and served as a model mucus environment. Diffusion coefficients were extracted from the ¹⁹F NMR signals of 1-fluoroadamantane (1FA) molecules encapsulated within HP-β–CD or MPEG–β–CD cavities. The results demonstrate that PEGylation substantially reduces β–CD–mucin adhesion, with longer PEG chains (2000 Da) providing more effective steric shielding than shorter chains (500 Da). These findings indicate that PEGylation can protect β–CD-included drugs during transport across mucosal barriers by minimizing unwanted β–CD–mucin interactions.