Effect of adsorption of charged molecules on the structure of Alginate gel

Natural origin, biocompatibility, low production cost and particularly ability of controlled release of the alginate gel are among the parameters which allow their utilization in pharmaceutical and food applications. For these purposes stability of gel, swelling and shrinkage due to the surrounding conditions like pH, temperature, ionic strength or interaction with molecules such as enzyme or substrate are essential in designing the material. The aim of this work is to study the interactions of various molecules (organic cations) with gel structure by quartz crystal microbalance with dissipation monitoring (QCM-D). The surface of silica quartz crystals was first modified by an APTMS treatment and two main approaches were followed in this study; first covering the QCM-D crystal with a thin layer of alginate gel, drying and re-swelling of the gel during the experiments followed by the adsorption of the molecules of interest. Secondly, in situ formations of alginate gel on the surface of QCM crystal by a layer by layer built-up and studying the polymeric film when it is exposed to different changes. In both approaches the effect of surrounding conditions such as pH, temperature and ionic strength is presented. The effect of the adsorption of organic cations on the gel stability was also investigated and discussed.