β-cyclodextrins modified with different chain lengths and their physical characterization with and without the attachment to gold nanoparticles.

Abstract

Beta-cyclodextrins (β-CDs) are a family of water soluble, naturally occurring cyclic oligosaccharides with a hydrophobic cavity that is used to host hydrophobic guest molecules. The numerous hydroxyl groups allow the native β-CD to be easily functionalized via synthetic modifications. By attaching modified CDs to the surface of gold nanoparticles (AuNPs) through a thiol moiety, its surface plasmon resonance effect can be taken advantage of. The AuNPs exhibit a photothermal effect upon irradiation which can alter the binding constant of guest molecules in β-CD hosts. Therefore, we attached novel β-CDs with different length ethylene glycol chains in hopes of studying in a distance-dependent manner the changes in the binding between the host and guest molecules. Prior to the attachment of the modified β-CDs to the surface of the AuNPs, Nile Red (NR) was utilized as a fluorescent guest to physically characterize the modified β-CDs.