Preparation and characterization of cyclodextrin functionalized polydimethylsiloxane films via interfacial self-assembly

Abstract Functionalized surfaces have many applications in areas such as sensor technology, selective adsorbents and controlled drug release. In this paper, polydimethylsiloxane (PDMS) films functionalized with a layer of cyclodextrin (CD) were prepared by using a facile and practical interfacial molecular self-assembly strategy. The surface and film structures were characterized and confirmed with FTIR-ATR and XPS spectroscopy. The prepared films were also tested for adsorption capacities for molecules of congo red and methylene blue and inclusion capabilities for antibacterial drug ciprofloxacin hydrochloride. For the CD layer preparation, amphiphilic cyclodextrin (am-β-CD) was synthesized by region-selective modification of the primary hydroxyl groups of β-cyclodextrin with long aliphatic chains, and then self-assembled on the interface between water and a PDMS organic casting solution. A layer of am-β-CD molecules was assembled onto the surface of the PDMS substrate via the mechanisms of molecular chain entanglements and hydrophobic interactions, which was confirmed by various characterization techniques. Fluorescent molecular staining experiments indicated that the self-assembled cyclodextrins layer on the PDMS substrate surface mostly retained the ability to include guest molecules. Adsorption tests showed that the functionalized films had a much higher adsorption capacity for the dye molecules than that of bare PDMS films. Inclusion experiments also showed that ciprofloxacin hydrochloride loaded functionlized PDMS films exhibited excellent antibacterial performance, indicating that the films could be used as a reservoir to store small drug molecules. All these results demonstrated that the novel films prepared could have potential applications in various areas, such as drug-loaded system and water purification.