Polyvalent incorporation of anionic β-cyclodextrin polymers into layer-by-layer coatings

Abstract

As versatile compounds forming host-guest complexes with a wide variety of hydrophobic molecules, cyclodextrins are widespread candidates to confer functionalities to surfaces, particularly for drug delivery applications in the field of biomaterials, and for analytic or preparative purposes in separative sciences. We report here on Layer-by-Layer coatings used to decorate surfaces with β-cyclodextrins, based on their capacity to allow the stress-free immobilization, and to maintain the accessibility and activity of functional components. We incorporated a β-cyclodextrin polymer into the coatings, either as the polyanionic component in association with polycationic polyethyleneimine or poly-l-lysine, or by post-loading into chondroitin sulfate/poly-l-lysine films. The study of the buildup mechanism, the structural features, and the interactions of the coatings with racemic mixtures of chiral hydrophobic compounds, provided evidence of the effective incorporation of the cyclodextrins and of their preserved functionality. The post-loading protocol led to noticeably high amounts of incorporated cyclodextrin polymer, which made it an unique, efficient route to embed cyclodextrins into Layer-by-Layer architectures. All the cyclodextrin-enriched films improved the chromatographic retention of hydrophobic compounds, and the polyethyleneimine/cyclodextrin systems showed additional enantioseparation properties. We view our coatings as relevant candidates for the design of drug nanoreservoirs atop biomaterials, and stationary phases in chromatographic devices.