| AVS 64th International Symposium & Exhibition | |
| Biomaterial Interfaces Division | Tuesday Sessions |
| Session BI-TuP |
| Session: | Biomaterial Interfaces Poster Session with Flash presentations |
| Presenter: | Zeinab Veisi, University of South Florida |
| Authors: | Z. Veisi, University of South Florida M. Cardenas, SRI International A. Cardenas-Valencia, SRI International R. Toomey, University of South Florida N. Alcantar, University of South Florida |
| Correspondent: | Click to Email |
We have used the mucilage of Opuntia ficus-indica cactus to fabricate ultra-thin films of surface-attached networks. The gelling properties and swelling behavior of these thin films were studied as a function of various stimuli to determine the main factors affecting the responsiveness of such layers.
Opuntia ficus-indica belongs to the cactaceae family, and is grown in dry regions. Its abundance makes it a promising commercial source of industrial pectin. Mucilage extracted from Opuntia ficus-indica is a heteropolysaccharide composed of a backbone chain structure of α-D-galacturonic acid and β-L-rhamnose interrupted by different neutral sugars. The carboxyl groups present in a polygalacturonic acid chain can be cross-linked in the presence of divalent ions to render hydrogel networks with conformations responsive to internal and external variables. The presence of a considerable amount of water within the polysaccharide matrices renders unique hydrophilic gels suitable to be used in a wide range of applications.
Thin films of surface-attached polysaccharide networks were fabricated by spin-casting solutions of mucilage. Ca2+ ions were then introduced to obtain cross-linked networks with adjustable extent of crosslinking. The fabricated surface-attached thin films of cross-linked polysaccharide were then characterized by Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) Spectroscopy and ellipsometry. Swelling behavior of the confined surfaces was studied as a function of temperature in contact with aqueous solutions, and their response was perturbed by different stimuli. Moreover, surface-attached networks were exposed to buffer solutions of pH of 9 and 2 to investigate the effect of charge concentrations on the response of networks.
The average water content in the networks as a function of temperature and the extent of crosslinking was precisely measured using ellipsometry. The results revealed that the extent of equilibrium water content and release profiles of thin films strongly depend on the degree of crosslinking. Moreover, the extent of equilibrium water uptake is affected by the values of pH of the media.
Our findings provide an improved understanding of the chemical properties, functionalities and the gelling behavior of thin films of surface-attached naturally occurring polysaccharides which can be employed for establishing responsive surfaces with tunable response suitable for the pharmaceutical and biotechnology industries.