Polymer-cyclodextrin complex self-assembled monolayer on gold surface and gold nanoparticle

Abstract

Applications of the polymer-cyclodextrin inclusion complex systems have mainly been in the area of controlled drug delivery which required that their bulk properties be well characterized. Our proposed study is to explore the possibilities of extending its applications into areas of confined geometries like self-assembled polymeric layers for biosensor applications or nanoparticulate systems for targeted drug delivery. We have successfully attached a monolayer of PEG via thiolate bonding onto the surface of gold. We were able to monitor the thiolate attachment as well as its subsequent ability to form inclusion complexes with cyclodextrin using the quartz crystal microbalance. We deduced that in order to promote inclusion complexation on a surface, the PEG chains must be packed such that the polymeric film layer is dense enough but yet the individual chains must be sufficiently mobile to promote inclusion complexation with cyclodextrins. We have also successfully synthesized gold nanoparticles stabilized with PEG and subsequently form inclusion complex with I?-cyclodextrin. Varying the concentration of I?-cyclodextrin resulted in varying degree of crystallinity and association leading to different forms of crystal formation.